DEV Community: darKLoin

day-07

darKLoin — Thu, 20 Oct 2022 14:25:32 +0000

Day- 09
Index
01.Exception Handling
02.try and catch
03.Multiple catch

Nested try block ---------------------------------START---------------------------- ----------------------------------01------------------------------
Exception Handling
~It is error that are occure during runtime then program is terminate avnormally to stop the termination or handling the exception is done.

error - occur during compile time
exception - occur during runtime of program.
~we use the following process
~~ try - monitor that code ,in wahic exception can occur it is going to have the exception.
~~ catch - it is going to handle the exception, which is thrown from by try block.
~~ throw - to manually throw a exception{user define}
~~ throws - it throws the exception which are generated by the method.
~~finally - that we want to excute everytime, even the exception is occur or not

different calss to handle exception
~Throwable - exception[run time], error[compile time]

example 01.1  : program whithout exception handle

class Main
{
    public static void main(String args[])
    {
        int  a = 1245 , k = 0;
        int d = a/0;
    }
}

Exception in thread "main" java.lang.ArithmeticException : / by zero 
    at Main.main(Main.java:6)

---------------------------------END----------------------------
---------------------------------02------------------------------
02.try and catch
~ now using the exception handle try/catch
rules to use:

try: it use to monitor your code for arising exception
catch: it use to handle the exception arise in the try block
syntax:
...
try{
...
}catch(..exception name..)
{
...to handle
}

example: program using the exception handle (try/catch)

class Main
{
    public static void main(String args[])
    {
        int k = 45 , kk = 0 ;
        try{
            int d = k/kk;
            System.out.println("form try block // never execute");
        }catch(ArithmeticException e )//exception name and exception object 'e'
        {
            System.out.println("form catch block after execute try");
        }
        System.out.println("after the catch block ");
    }
}

form catch block after execute try
after the catch block

~ we can see here that statement in the try block is not execuate once the try block find and exception
NOTE: do not write the try/catch block in a single statement it should follow the above written syntax
example: program each iteration of the for loop obtains two random integers. Those two integers aredivided by each other, and the result is used to divide the value 12345. The final result is put into a. If either division operation causes a divide-by-zero error, it is caught, the value of a is set to zero, and the program continues.

import java.util.*;
class Main
{
    public static void main(String args[])
    {
        int a ;
        Random rr = new Random();
        for(int i = 0 ; i < 100 ; i++)
        {
            int numone = rr.nextInt();
            int numtwo = rr.nextInt();
            try{
                int numthird = numone/numtwo;
                int a = 12345/ numthird;
                // caught by devision as xero
            }catch(ArithmeticException e)
            {
                a = 0 ; // a is set to 10
            }
            System.out.println("a: "+a);
        }
    }
}

~this will example will show the exception handling and continues of the progarm means it only get terminate until its condition satisfied

---------------------------------END----------------------------
---------------------------------03------------------------------

Multiple catch ~ In a program we can have a try block with the multiple catch block when a try block contain more than one exception to handle ~ multiple catch block will work as per the exception define in them. example: progarm having the a that devision is done by zero and a array, size of array is define by the command line argument and another array assigning a value which is out of index of that array.

class Main
{
    public static void main(String args[])
    {
        int a = args.length;
        int c = a+1;
        try{
            int f = c/a;
            int c[] = {1};
            c[33] = 45;
        }catch(ArithmeticException e )//the exception will be this without any commandline argument
        {
            System.out.println("it is from 1st catch ");
            System.out.println(" Devide by zero : "+ e);
        }
        catch(ArrayIndexOutOfBoundsException e )// the exception will be this with command line argument
        {
            System.out.println("it is form 2nd catch");
            System.out.println(" Index of array is out of bound : "+ e);    
        }
    }
}

~while giving the multiple catch block remeber that exception sub-class should be come before the excetion super-class
~if the exception sub-class will come after the exception super-class then the sub-class catch block will not execute
example : program showing the importance of placing super-class exception and sub-class exception

class Main
{/* In java unreachable code is an error */
    public static void main(String args[])
    {
        int a = 0, j , c ;
        int k = a +1;
        try{
            c = k/a;
            int d[] = {41};
            d[4512] = 1;
        }catch(Exception e )
        {
            System.out.println("this is frome Exception super-class "+e);
        }
        catch(ArithmeticException e )//this catch block will never reach because the ArithmeticException is a sub-class of the Exception
        {
            System.out.println("from airthmetic exception "+e);
        }
    }
}

---------------------------------END----------------------------
---------------------------------04------------------------------

Nested try block ~ Nested try are used when catch block does not have the particular exception handler for the exception of try block then try statement's catch handler are inspected for a match. it continues until one of the catch statements succeeds, or until all of the nested try statements are exhausted example : program showing the nested try block

class Main
{
    public static void main(String args[])
    {
        int a = args.length;
        try{
            int l = 5;
            l = l/a;//devide by zero exception
            System.out.println("a :"+a);
            try{
                if(a == 1)
                    a = a/a-a;// devide by zero   

                if(a == 2)
                {
                    int c[] = {44};
                    c[451] = 1;//array index boundation
                }
            }catch(ArrayIndexOutOfBoundsException)
            {
                System.out.println("array index problem... : "+e);
            }               
        }catch(ArithmeticException e)
        {
            System.out.println("airthmetic exception first catch : "+e);
        }
    }
}

---------------------------------END----------------------------
---------------------------------05------------------------------

throw
~it allow to create and throw the exception explicitly
~exception thrown can be done by two ways
1. creating our own throw statment
2. using parameter in catch statement
~onece the thorw statement encounctered then the all code after throw will not execute
~the try exception inspecte the enclose catch statement for matching if matched then control transfer to that and if not hen inspecte the next try statement and so on if there is no matching catch is available then it transfer to default excepton handler.

example: program contain user created throw statement for handle

class Main
{
    static void throwexp()
    {
        try{
            throw new NullPointerException("hello");
        }catch(NullPointerException e)
        {
            System.out.println("caught throw hello form throwexp");
            throw e;
        }
    }

    public static void main(String args[])
    {
        try{
            throwexp();
        }catch(NullPointerException e)
        {
            System.out.println("again caught throw hello from MAIN");
        }
    }
}

---------------------------------END----------------------------
---------------------------------06------------------------------

throws
~when method causing an exception that cannot handle then it must specified this behavior
~behavior is specified by including the 'throws' clause in the declaretion of method
all type of exceptions that method might throw must br declared in throws clause
like
type method_name(parameter) throws exception list
{
....
}

example : program contain the throws statement

class Main
{
    static void throwscheck() throws IllegalAccessException
    {
        System.out.println("inside throwscheck");
        throw new IllegalAccessException("throwName");
    }

    public static void main(String args[])
    {
        try{
            throwscheck();
        }catch(IllegalAccessException e )
        {
            System.out.println("inside Main catch \n caught : "+e);
        }
    }

}

---------------------------------END----------------------------
---------------------------------07------------------------------
07.finally
~it is used to bypass the exception-handling mechanism and execute the reamain code...
~finally block will execute weather or not exception is thrown
~when an exception is throw then the finally block will execute even no catch statement matches the exception
~when there is uncaught exceotion or explicit return statement then the finally clause execute just before the method returns.
~the finally clause is optional, it help when there is a exception in mid of file and to skip the abnoraml termination we use the finally keyword.
example : program showing the all three above written use of finally

class Main {
    static void classA() {
        try {
            System.out.println("from classA try, no return, yes exception");
            throw new RuntimeException("runtime");
        } finally {
            System.out.println("from classA finally");
        }
    }

    static void classB() {
        try {
            System.out.println("from classB try, return , no exception");
            return;
        } finally {
            System.out.println("from classB finally");
        }
    }

    static void classC()
    {
        try{
            System.out.println("from classC try, no return, no exception");
        }finally
        {   
            System.out.println(" from classC finally");
        }
    }

    public static void main(String args[]) {
        try {
            classA();
        } catch (RuntimeException e) {
            System.out.println("caught classA e:" + e);
        }
        classB();
        classC();
    }
}

---------------------------------END----------------------------
---------------------------------08------------------------------
08.Creating own Exception Sub-class
~When we want to create a own exception to handle the situation specific to your application and program
~it is done by just creating the sub-class of Exception and sub-class should be a sub-class of Throwable
~it inherit the method provided by the Throwable, and Exception does not define the method of its own

example :

class ownException extends Exception {
    private int detail;

    ownException(int a) {
        detail = a;
    }

    public String toString() {
        return "OwnException[" + detail + "]";
    }
}

class Main {
    static void compute(int a) throws ownException {
        System.out.println("Called compute(" + a + ")");
        if (a > 10)
            throw new ownException(a);
        System.out.println("Normal exit.");
    }

    public static void main(String args[]) {
        try {
            compute(1);
            compute(20);
        } catch (ownException e) {
            System.out.println("Caught " + e);
        }
    }
}

day-07

darKLoin — Thu, 20 Oct 2022 14:24:38 +0000

Day-07
Index:-
01.Local variable
02.Instance variable
03.Static variable
04.Static method
05.this keyword
06.Method overloading
07.Object as a parameter

------start----
----01----

Local Variable ~local variable are declared inside method inside constructor inside any block of code variable as a method parameter

~Whenever this method, constructor, any block of code is called in program then the all local variable are initialize.
OR
~When the constructor method ot block of code is over then variable get destroy.
~life of local variable is untill the block of code is working or running
~locak variable cnanot be decllared as private or protected.
------end -----
-----02-----
02.Instance Variable
~these variable are declared inside a class but outside a method.
~instance variable is also known as the data member, field, attribute.
~whenever we create a a object, this instance variable get initalized.
~and every object will cerate a seprate copy of the instane variable.
~life time of a instance variable is equal to the life time of a class
~when the class is terminated then all the instance variable get terminate auto matically.
----end ---
----03-----
03.Static/class variable
~this variable are declerade with the 'static'keyword.
~static variable declearad inside a class and outside a method.
~in case of static variable all object get a same copy of variable or all objects are sharing a variable.
~we use this class/static variable to declare a constant variable
~In java we don't have the global variable but static variable are used to create global vatiable.

example: how to work with static variable

class test
{
    int instanceVar ;
    static int staticVar ;
    void setInstance(int inputInstance)
    {
        instanceVar = inputInstance;
    }
    void setStatic(int inputStatic)
    {
        staticVar = inputStatic; 
    }
    int returnInstance()
    {
        return instanceVar;
    }
    int returnStatic()
    {
        return staticVar;
    }
}
class Main
{
    public static void main(String args[])
    {
        test obFirst = new test();
        test obSecond = new test();

        obFirst.setInstance(9);
        obSeconf.setInstance(23);

        System.out.println("instance variable using first object: "+obFirst.returnInstance());
        System.out.println("instance variable using second object: "+obSecond.returnInstance());

        obFirst.setStatic(90);
        obSeconf.setStatic(230);

        System.out.println("static variable using first object: "+obFirst.returnStatic());
        System.out.println("static variable using second object: "+obSecond.returnStatic());
    }
}

~we can access the static variable outside the class without using the object but by using the class name of static variable.
-------end -----
---------04--------
04.Static Method
~static method can access the static variable directly.
~variable doesn't decleared as staic cannot be access by the static method.
example: showing static method accessing the different variables

class test
{
    int instanceVar = 3;
    static int staticReturn() 
    {
        return instanceVar;
    }
}
class Main
{
    public static void main(String args[])
    {
        //test obFirst = new test();
        System.out.println("accessing the static method using instance variable: "+test.staticReturn());
    }
}

------end -----
-------05------
05.this keyword
example: explain the this keyword by taking a example

class box
{
    double width , height, length;
    box(double w, double h, double l)
    {
        width = w;
        height = h;
        lenght = l;
    }
    double volume()
    {
        return witdh*height*length;
    }
}
class Main
{
    public static void main(String args[])
    {   
        box ob - new box(10,20,30);
        System.out.println("Volume of box is: "+ob.volume());
    }
}

~this program will work fine there is no caught while compling and running.
~but what if we made constructor local variable as same name as the instance variable [OR changing the parameter variable as instance variable] then it will generate error
shown in below program

    box(double width, double height, double lenght)
    {
        width = width;
        height = height;
        lenght = lenght;
    }

~using this we are not able to initiallize the instance variable the value are only reassign to the local variable
~and we want to kept the same name of parameter than we have to use the 'this' keyword shown in below program

class box
{
    double width , height, length;
    box(double width, double height, double lenght)
    {
        this.width = width;
        this.height = height;
        this.lenght = lenght;
    }
    double volume()
    {
        return witdh*height*length;
    }
}
class Main
{
    public static void main(String args[])
    {   
        box ob - new box(10,20,30);
        System.out.println("Volume of box is: "+ob.volume());
    }
}

~here this keyword is referring to the object which created in main class or
~'this' is always associated with object
------end------
-----06------
06.Method overloading
~method overloading means more than one method with the same name and their parameters are different
~polymorphism- means single interfave. multiple behaviour
behaviour is identified by parameter
example: show the working of method overloading

class methodoverloadin
{
    void test()
    {
        System.out.println("no parameter");
    }
    void test(int a )
    {
        System.out.println("a : "+a);
    }
    void test(int a, int b)
    {
        System.out.println("a and b : "+a+"  "+b );
    }
    double test(double k)
    {
        System.out.println("a :"+a);
        return a*a;
    }
}
class Main
{
    public static void main(String args[])
    {
        methodoverloading ob = new methodoverloading();
        double result;
        ob.test();
        ob.test(5);
        ob.test(10,20);
        result = ob.test(12.543);
        System.out.println("result :"+result);
    }
}

---end
----07-----
07.object as a parameter
~when we are creating a class it is user define data-type
~when we create a object of that class then we are createing the variable of user defined data-type
example


java    
class test 
{
    int a,b;
    test(int i, int j)
    {
        a =i;
        b =j;
    }
    booleand equals(test o)
    {
        if(o.a == a && o.b == b)
            return true;
        else 
            return flase;
    }
}
class Main
{
    public static void main(String args[])
    {
        test obOne = new test(10,20);
        test obTwo = new test(10,20);
        test obThree = new test(1,2);

        System.out.println("obOne ==  obTwo : "+obOne.equals(obTwo));
        System.out.println("obOne ==  obThree : "+obOne.equals(obThree));
    }
}

---end
----08-----
08. question
1. Write a program to construct Box class that stores width, height, and depth of the box and display the dimension on to the screen and also calculate the volume of the box using method.(Demonstration of method and calling method and object creation).
2. Implement Money class. This class should initialize a rupee and paisa amount with 0-99 paisa and the paisa being the sign as the rupees. The class should at minimum have all reasonable cinstructors, addition, and substration methodsm and main() method that provides a through test of all the methods in the class.
3. Create a complex number class, the class should have a constructor and methods to add, subtract and multiply two complex numbers, and to return the real and imaginary parts.
4. Create a class Rectangle. The class has two attributes lenght and width, each of which defaults to 0. It has methods that calculate the perimeter and area of the rectangle. It has set and get methods for both length and width. The set method should verify that length and width are floating point number larger than 0.0 and less than 20.0.
5. Write a program to constructor Box class that stores witdth, height and depth of the box and use different types of constructors to initialize various object of the box class and display volume of different boxes.

DAY-06

darKLoin — Thu, 20 Oct 2022 14:23:55 +0000

Day- 06
Index
01.Super
02.Final
03.Extra problem
03.1: Create a simple class to compare the value of two integers, where these two integers belong to different objects of the same class using method which takes object as a parameter.(Dempnstration of method taking object as parameter)
03.2: Create a simple calss to compare the value of two integers, where these two integers belong to different objects of the same class using method which takes object as a parameter and returns the object which contains the larger value.(Demonstration of method returning object)
03.3: Write a program to perform garbage collection.
03.4:143 write a program to calculate the factorial of the given number using recursion.
03.5: Demonstration of static variables to perform the addition the addition without creaeting any object in the class.(Demonstration of static variable and static methods)
03.6: Write a program to print your name by using the concept of command line arguments passing mechanism.
03.7: Write a program to constructor Box calss that stores width, height and depth of the box and extend Box class to include weight parameter in BoxWeight class and calcuate the volume and weight of different boxes.(Demonstration of single level inheritance)
03.8 Write a program to construct Box class that stores width,height and depth of the box and extends Box class to include weight parameter in BoxWeight class and calculate the volume and weight of different boxes with the help of super keywaord(Demonstration of super keyword to call base class constructor).
03.9 Demonstration of calling order of constructors in multilevel inheritance as in the above program.
03.10 Demonstration of method overriding with the help of supr keywaord.
03.11 Demonstration of instance variable hiding with the help of super keyword.
03.12 Demonstration of multilevel inheritance by extending class A in class B and class C, all classesmust have some instance variables and methods.
03.13 Define a class MotorVehicle as described below:
a. modelName
b. modelNumber
c. modelPrice
Methods:
d. display() method to display the name, price and model number.
Define anothe class named Car that inherits the class MotorVehicle and has the following:
Data Members:
e. discountRate
Methods:
f. display() method to display the Car name, car model number, car price and the discount rate.
g. Discount() method to compute the discount
Create the classes MotorVehicle and Car with suitable constructor and test it.
03.14 Define a class name as College as shown below:
Data members:
a. Collegename
b. Address
Method:
c. showCollegeDetails() to show the details about the college
define another class named Department that inherits the College and has the following:
Data members:
d. departmentName
e. hodName
Method:
j. showFacultyMemberDetails() to show the details of the faculty members within a particular dapartment in a college.
Create classes for College, Department and FacultyMember with suitable constructor and test them.

---------------------------------START----------------------------
----------------------------------01------------------------------
01.Super
~it refer to its parent class
~If the object of child class want to access the feature of parent class with the help of child class object then we use the keyword 'super'

~purpose/way of use 'super'
1.use to call the method of super class/parent
2.use to access the member variable of the super class/parent class
3.use to invoke the constructor of the super class parent class
example: showing the '1' use of super --> calling the method from parent class using super

class A
{
    void show()
    {
        System.out.println("Super class show method A");
    }
}
class B extends A
{
    void show()
    {
        System.out.println("Sub class show method B");
    }+
}
class Test
{
    public static void main(String args[])
    {
        A a = new A();
        a.show();//calling first show() using the object of class A

        B b = new B();
        b.show();//calling second show() using the object of class B
    }
}
//we can call the show() function from second class object using the super keywaord

~to call a parent class show function from the child class object we have to add the super keyword in the show function of child class in first line
as shown below

class A
{
    void show()
    {
        System.out.println("Super class show method A");
    }
}
class B extends A
{
    void show()
    {
        super.show();
        System.out.println("Sub class show method B");
    }
}
class Test
{
    public static void main(String args[])
    {
        //A a = new A();
        //a.show();//calling first show() using the object of class A

        B b = new B();
        b.show();//calling first and second show() using the object of class B
    }
}

~we have to add in first line of the function because the parent class should get initiallize first, if it does not then it will generate an error

example: showing the '2' use of super --> accessing the member of parent class variable using super

class A
{
    int b = 30;
}
class B extends A
{
    int b = 12;//creating same as the parent class instance variable change the value
    void show()
    {
        System.out.println("Sub class variable: "+b);//12
        System.out.println("Super class variable: "+b);//12
    }
}
class Test 
{
    public static void main(String args[])
    {
        B a = new B();
        a.show();
    }
//if we see the output it will give the both value of b from the same child class as 12

~to call the instance variable of parent class using super keyword as show below

class A
{
    int b = 30;
}
class B extends A
{
    int b = 12;//creating same as the parent class instance variable change the value
    void show()
    {
        System.out.println("Sub class variable: "+b);//12
        System.out.println("Super class variable: "+super.b);//30
    }
}
class Test 
{
    public static void main(String args[])
    {
        B a = new B();
        a.show();
    }
}

example: showing the '3 ' use of super --> invoke the constructor of parent class variable using super

class A
{
    A()
    {
        System.out.println("constructor of class A.");
    }
}
class B extends A
{
    B()
    {
        System.out.println("constructor of class B");
    }
}
class C extends B
{
    C()
    {
        System.out.println("constructor of class C");
    }
}
class test
{
    public static void main(String args[])
    {
        //B bb = new B();
        C cc = new C();// this will call the all constructor by their order of Inheritance
    }
}

~in above program dosen't matter which constructor you are it will show as its oeder of inheritance
~to invoke the constructor without order we use the super keyword
example :

class A
{
    A()
    {
        System.out.println("constructor of class A.");
    }
}
class B extends A
{
    B(int a)
    {
        System.out.println("constructor of class B "+a);
    }
}
class C extends B
{
    C()
    {
        super(11);//it will find the similer constructor which have the a parameter
        //the super keyword can not be in second line 
        System.out.println("constructor of class C");
    }
}
class test
{
    public static void main(String args[])
    {       
        C cc = new C();
    }
}

example : using all super way

class circle
{
    float radius;
    final float pi =3.14f;
    circle()
    {
        radius = 1.0f;
    }
    circle(float radius)
    {
        this.radius = radius;
    }
    float getArea()
    {
        return pi*radius*radius;
    }
}
class cylinder extends circle
{
    flaot height;
    cylinder(float radius , float height)
    {
        super(radius);
        this.height = height;
    }
    float getArea()
    {
        return 2*super.getArea()+2*pi*radius*height;
    }
}
class test
{
    public static void main(String args[])
    {
        circle c = new circle(1.5f);
        System.out.println("Area of circle is : "+c.getArea());

        cylinder cc = new cylinder(1.5f,3.5f);
        System.out.println("Area of cylinder is : "+ cc.getArea());

    }
}

---------------------------------END------------------------------
--------------------------------02--------------------------------
02.final
~it also has the three uses

1.to declear the constant
2.to disallowed the method overeiding function
3.to disallowed a class to get inherited

example : use of final

class demo
{
    int m = 100;
    void show(int x)
    {
        System.out.println("Super class show method:"+x);
    }
}
class demo2 extends demo
{
    void show(int x)
    {
        System.out.println("Sub class show method:"+x);
    }
}
class rest
{
    public static void main(String args[])
    {
        demo2 dd = new demo2();
        dd.show(45);
    }
}// it is normal program it will not create any error.

example : showing the use of final keyword

final class demo// it will not allowed its any child after final
{
    final int m = 100;
    final void show(int x)
    {
        System.out.println("Super class show method:"+x);
    }
}
class demo2 extends demo
{
    void show(int x)// it is the same as the above function or it will generate the error because of final keyword
    {
        System.out.println("Sub class show method:"+x);
    }
}
class rest
{
    public static void main(String args[])
    {
        demo2 dd = new demo2();
        dd.show(45);
        m += 45;// it will create error because of the final keyword 
    }
}

---------------------------------END------------------------------
example: using super

class Box
{
    private double height;
    private double width;
    private double depth;
    Box(Box ob)
    {
        width =  ob.width;
        height = ob.height;
        depth = ob.depth;
    }
    Box(double w, double h, double d)
    {
        width = w;
        height = h;
        depth = d;
    }
    Box()
    {
        width=height=depth=-1;
    }
    Box(double len)
    {
        width=height=depth=len;
    }
    double volume()
    {
        return width*height*depth;
    }
}

class BoxWeight extends Box
{
    double weight;
    BoxWeight(BoxWeight ob)
    {
        super(ob);
        weight = ob.weight;
    }
    BoxWeight(double w, double h, double d, double m)
    {
        super(w,h,d);
        weight = m;
    }
    BoxWeight()
    {
        super();
        weight = -1;
    }
    BoxWeight(double m , double len)
    {
        super(len);
        weight = m;
    }
}
class shipment extends BoxWeight
{
    double cost;
    shipment(shipment ob)
    {
        super(ob);
        cost = ob.cost;
    }
    shipment(double w, double h, double d,double m, double c)
    {
        super(w,h,d,m);
        cost = c;
    }
    shipment()
    {
        super();
        cost = -1;
    }
    shipment(double len, double c)
    {
        super(len);
        cost =c ;
    }
}
class tost
{
    public static void main(String args[])
    {
        shipment rip = new shipment(10,10,10,10,10);
        System.out.println("volu,e id :"+ rip.volume());
    }
}

---------------------------------END------------------------------
--------------------------------03--------------------------------
03.Extra problem
problem:
obj_para_03_1.java : Create a simple class to compare the value of two integers, where these two integers belong to different objects of the same class using method which takes object as a parameter.(Dempnstration of method taking object as parameter)
problem:
obj_para_03_2.java : Create a simple calss to cmpare the value of two integers, where these two integers belong to different objects of the same class using method which takes object as a parameter and returns the object which contains the larger value.(Demonstration of method returning object)
problem:
GC_03_3.java : Write a program to perform garbage collection.
problem:
recursion_03_4.java : write a program to calculate the factorial of the given number using recursion.
problem:
addition_03_5.java : Demonstration of static variables to perform the addition the addition without creaeting any object in the class.(Demonstration of static variable and static methods)
problem:

cmd_arg_03_6.java : Write a program to print your name by using the concept of command line arguments passing mechanism.
problem:
Box_Weight_03_7.java : Write a program to constructor Box calss that stores width, height and depth of the box and extend Box class to include weight parameter in BoxWeight class and calcuate the volume and weight of different boxes.(Demonstration of single level inheritance)
problem:
Box_Weight_super_03_8,java : Write a program to construct Box class that stores width,height and depth of the box and extends Box class to include weight parameter in BoxWeight class and calculate the volume and weight of different boxes with the help of super keywaord(Demonstration of super keyword to call base class constructor).
problem:
Inheri_multilevel_03_9.java : Demonstration of calling order of constructors in multilevel inheritance as in the above program.
problem:
overriding_super_03_10.java : Demonstration of method overriding with the help of supr keywaord.
problem:
instance_super_03_11.java : Demonstration of instance variable hiding with the help of super keyword.
problem:
Inheri_multilevel_extend_03_12.java : Demonstration of multilevel inheritance by extending class A in class B and class C, all classesmust have some instance variables and methods.
problem:
MotorVehicle_03_13.java : Define a class MotorVehicle as described below:
a. modelName
b. modelNumber
c. modelPrice
Methods:
d. display() method to display the name, price and model number.
Define anothe class named Car that inherits the class MotorVehicle and has the following:
Data Members:
e. discountRate
Methods:
f. display() method to display the Car name, car model number, car price and the discount rate.
g. Discount() method to compute the discount
Create the classes MotorVehicle and Car with suitable constructor and test it.
problem:
College_03_14.java : Define a class name as College as shown below:
Data members:
a. Collegename
b. Address
Method:
c. showCollegeDetails() to show the details about the college
define another class named Department that inherits the College and has the following:
Data members:
d. departmentName
e. hodName
Method:
j. showFacultyMemberDetails() to show the details of the faculty members within a particular dapartment in a college.
Create classes for College, Department and FacultyMember with suitable constructor and test them.

---------------------------------END------------------------------

day-05

darKLoin — Thu, 20 Oct 2022 14:22:33 +0000

DAY-05
Index:-
01.Static Variable
02.Commandline argument
03.Garbage collection
04.Finalize keyword
05.Inheritance
06.Dynamic method dispatch
---------------------------------START----------------------------
----------------------------------01------------------------------
01.Static Variable
~It is comman to all among the object or shared among all the objecs
~constructor cannot used for te static variable
constructor--> shared variable/instance variable
static variable--> class variable shared among all the objects
~for the static variable we cannot use the constructor, constructor is for the static vatiable is 'statc' keyword
example: 01.1

class useStatic 
{
    static int c = 3;
    static int d ;
    static void show(int x)
    {
        System.out.println("X="+x);
        System.out.println("c="+c);
        System.out.println("d="+d);
    }
    static//it is the constructor for the static variable
    {
        System.out.println("static block is initialize.");
        d = c*2;
    }
    public static void main(String[] args)
        {
        show(200);//here it is just calling by it name
        }
}

---------------------------------END------------------------------
--------------------------------02--------------------------------
02.Commandline Argument
~in normal program we pass the value or input during run time to get input before running,
~we have the parameter in main as '(String args[])'
it rell that we can input before running the program
it is having a array with name args, its size depends on the input in the commandLine or before running value input
example: 02.1

class commandLine
{
    public static void main(String args[])
    {
        for(int i =0 ; i<args.length ; i++)
        {
            System.out.println("location args["+i+"] = "+args[i]);
        }
    }
}

C:\Users\user\Desktop>javac commandLine.java
C:\Users\user\Desktop>java commandLine hello how are you 123 45 1 2 3 4 5
location args[0] = hello
location args[1] = how
location args[2] = are
location args[3] = you
location args[4] = 123
location args[5] = 45
location args[6] = 1
location args[7] = 2
location args[8] = 3
location args[9] = 4
location args[10] = 5

~using this we can give input in any program from CommandLine only
---------------------------------END------------------------------
--------------------------------03--------------------------------
03.Garbage Collection
~in other languages we have to delocalize or delete the memory after the use during progamm
but in java it is done peridiocally by it means system will do this for you automatically,it will delete the free the memory of assign object or variable or when the variabel not come in use for a long time.
it will use the 'System.gc()' function to do this or we can call it when ever we want
~during automatic process of delocalizing memory we want to store some data, file or memory then we have to use the 'finalize()' function and the code in this finalize block will excute and do the process before delocalizing
exmaple: 03.1

class garbagecoll
{
    public static void main(String args[]) throws InterruptedException
    {
        garbagecoll t1 = new garbagecoll();
        garbagecoll t2 = new garbagecoll();
        t1 = null;
        System.gc();
        t2 = null;
        Runtime.getRuntime().gc();
    }
    protected void finalize() throws Throwable
    {
        System.out.println("Garbage collector called...");
    }
}

---------------------------------END------------------------------
--------------------------------04--------------------------------
04.Inheritace
~we all have seen that we get the geans or characterstics from our parent and java language is also follow the same type.
~a CHILD class can use or perform the task objects written in the Parent class or CHILD class can have it own special characterstics or property which can not be transform to their PARENT class.
parent class ->> SUPER CLASS[transform its characterstics to SUB-SUPER CLASS ]
child class ->> SUB-SUPER CLASS[it can also transform its characterstics to other SUB-SUB-SUPER CLASS, but it can not transform to it parent class]
~it also called as "reuse of code-- reusability" child class can use the code of parent class
~command/generalize objects are written in the PARENT CLASS
~special/specified objects are writtrn in the CHILD CLASS
NOTE:: anything defined as private by PARENT class is not accessible to CHILD class
~kind of inheritance

Simple Inheritace (one parent class) ---> (one child class) A(PARENT) ---> B(CHILD)
Multi-level Inheritace (two parent) ---> (one child) A(GRAND-PARENT) --> B(PARENT) ---> C(CHILD) 3.Multiple Inheritace(in java it is done by 'interface') (two different parent) ---> (one child) A(PARENT),B(PARENT) ---> C(CHILD) ~how it is written base class(parent) derived class(child)

class parent
{...
}
class child extends parent

example:

class Motorvehicle
{
    int speed;
    String modelname;
    int modelyear;
    int noofpassenger;

    Motorvehicle()
    {
        speed = 250;
        modelname = "KTM";
        modelyear = 2021;
        noofpassenger = 2;
    }

    Motorvehicle(int ms , int my , int nop ,String mn)
    {
        speed = ms;
        modelyear = my;
        noofpassenger = nop;
        modelname = mn;
    }

    void show()
    {
        System.out.println("Maximum speed is: "+speed );
        System.out.println("Model Year is: "+modelyear );
        System.out.println("Model Name is: "+modelname );
        System.out.println("Number Of Passenger is: "+noofpassenger);
    }
}
class Bike extends Motorvehicle
{
    boolean kick;
    boolean self;

    Bike()
    {
        kick = true;
        self = false;
    }
    Bike(boolean k , boolean s )
    {
        kick = k ;
        self = s;
    }

    void show()
    {
        System.out.println("Bike is kick start:"+ kick);
        System.out.println("Bike is self start:"+ self);
    }
}
class Inheritance
{
    public static void main(String args[])
    {
        Motorvehicle obj1 = new Motorvehicle();
        Bike obj2 = new Bike();

        //Motorvehicle ee;
        //ee = obj1;
        //obj1.sohw();
        //ee = obj2;
        //obj2.show();


        obj1.show();
        obj2.show();
    }
}

~here the same variable doing the different function or task this is known as 'dynamic method dispatch'

~Dynamic Method Dispatch: means the result of a function is depend on the runtime or the assign value.

~Method Overriding:: when two or more class (parent, child) have function with same name and same parameter then it us called method overriding
eg: the 'show()' function in the previous program
example:

class A 
{
    int i  =0 ;
    void overriding(int k)
    {
        i = k;
    }
}
class B extends A
{
    void overriding(int k)
    {
        i = 2*k;
        System.out.println("the value of i is:"+i);
        }
}
class test
{
    public static void main(String args[])
    {
        B ob = new B();
        ob.overriding(220);
    }
}

---------------------------------END------------------------------

day-04

darKLoin — Thu, 20 Oct 2022 14:21:06 +0000

DAY-04
Index
01.Class
01.1 example
02.Constructor
02.1 example
02.2 example
03.Constructor overloading
03.1 example
04.Extra problem
04.1: Write a program to generate the Fibonacci series
04.2" Write a program to generate the sorting order of array
04.3: Design a class named Rectangel to represent a recrangle. The class contains:
-Two double data fields named width and height that specify the width and height of the rectangle. The default values are 1 for both width and height.
-A no-arg constructor that crates a default rectangle.
-a constructor that creates a rectangle with the specified width and height.
-A method named getArea()that returns the area of this rectangle.
-A method named getPrtimeter() that returns the perimeter.
Implement the class. Write a test program the creates two Rectangle obgects--one with width 4 and height 40 and the other with width 3.5 and height 35.9. Display the width,height,area and perimeter of each rectangle in this oreder.
04.4: Design a class named Account that contains:
-A private int data field named id for the account(default 0).
-A private double data fiels named balance for the account(default 0).
-A pricate double data field named annualInterestRate that stores the current interest rate(default 0).Assume all accounts have the same interest rate.
-A private Data data field named dateCreated that stores the date when the account was created.
-A no-arg constructor that creates a default account.
-A constructor that creates an account with the specified id and initial balance
-The accessor and mutator methods for id,balance and annaulInterestRate.
-The accessor method for dateCreated.
-A method named getMonthlyInterestRate() that returns the monthly interest rate.
-A method named withdraw that withdraws a specified amounnt from the account.
-A method named deposit that deposits a specified amount to the account.
Implement the class. Write a test program that creates an Account object with an account ID of 1122,a balance of $20,000 and an annual interest rate of 4.5%. Use the withdraw method to withdraw $2,500 use the deposit method to deposite $3,000 and print the balance, the monthly interest, and the date when this account was created.
04.5: Create a class recangle. The class has two attributes, lenght and width. Each of which default to 0. It hs method that calculate the perimeter and area of the rectangel. It has set and get method for both length and width. The set method should verify that length and width are floating-point number larger thab 0.0 and less than 20.0.

---------------------------------START----------------------------
----------------------------------01------------------------------

01.Class
01.1 example

class circle
{
    float pi = 0.0f;
    float radius;
    void setdata(float rad)
    {
        radius = rad;
    }
    float calcu()
    {
        float area = pi*pi*radius;
        return area;
    }
}
class circlearr
{
    public static void main(String[] args)
    {   
        circleaa = new circle();
        aa.pi = 3.14f;
        aa.setdata(20.0f);
        System.out.println("Area of circle is: "+aa.calcu());
    }
}

~in above program the value of 'pi' can be modified in class
~to make variable unchanged by objects we have to private keyword before declearing the keyword.
example: 01.2

class circle
{
    private float pi = 0.0f;
    private float radius;
    void setdata(float rad)
    {
        radius = rad;
    }
    float calcu()
    {
        float area = pi*pi*radius;
        return area;
    }
}
class circlearr
{
    public static void main(String[] args)
    {   
        circleaa = new circle();
        aa.pi = 3.14f;// it will generate error
        aa.setdata(20.0f);
        System.out.println("Area of circle is: "+aa.calcu());
    }
}

---------------------------------END------------------------------
--------------------------------02--------------------------------
02.Constructor
~in previous program 'circle()' keyword is the constructor.
~or using the class name to create objects
~constructor has same name as class in which they reside.
~constructor are syntactically same to a method/function.
~constructor get called automaticallt when objects is created using new operator.
~constructor have no return type, not even void.
~implict return type of constructor is class type itself.
syntax:
constructor_name(parameter)//way to write a constructor
{...}

    return_type function_name(parameter)//way of writting noramal code
    {...}

~if a user has not define any constructor in a class than it have by default constructor.
default constructor: it automatically initialize the class instance variable by zero.
-once user created constructor thel there is no default constructor.
example: 02.1:

java
class room
{
    float length, height , width ,vol;
    room()//it does not have any parameter
    {
        length =20.0f;
        height = 14.0f;
        width = 10.0f;
    }
    float volume()
    {
        vol = length * height * width;
        return vol;
    }
}
class arrroom
{
    public static void main(String args[])
    {
        room aa = new room();
        System.out.println("volume of the room is: "+aa.volume());

        //if we create the one more object then it will also have the same value 
        room bb = new room();
        System.out.println("volume of the second room is: "+bb.volume());

    }
}

~constructor in above program is parameterless constructor because it doesn't have any parameter
~to create the parameterized constructor we have to add the parameter in constructor

example: 02.2

class room
{
    int length, height , width ,vol;
    room(int l,int h,int w)//it is having some parameter
    {
        length = l;
        height = h;
        width = w;
    }
    int volume()
    {
        vol = length * height * width;
        return vol;
    }
}
class arrroom
{
    public static void main(String args[])
    {
        room r1 = new room(2,5,4);
        System.out.println("volume of the room is: "+r1.volume());

        //if we create the one more object then it will also have the same value 
        room r2 = new room(5,5,5);
        System.out.println("volume of the second room is: "+r2.volume());

    }
}

---------------------------------END------------------------------
--------------------------------03--------------------------------
03.Constructor overloading
~Constructor Overloading:
when the same constructor is able to do the different things depending on the calue what kind of value are passing to that constructor
~overloading is concept of polymorphism
~means -- when we assign the multiple task to same thing
example :

class rectangle
{
    int length , height;
    rectangle()//parameterless
    {
        length = 10;
        height = 20;
    }
    rectangle(int x ,int y )//parameterized
    {
        lenght =x ;
        height = y ;
    }
    int getarea()
    {
        return lenght*height;
    }
}

~constructor overloading is differential by the type, and number of parameter
like first constructor have no parameter and second has two parameter or may be third parameter have other type of three parameter
~when we create two constructor with same name and pass the different value this is called as the constructor overloading.
example: 03.1

class rectangle
{
    int length , height;
    rectangle()//parameterless
    {
        length = 10;
        height = 20;
    }
    rectangle(int x ,int y )//parameterized
    {
        length =x ;
        height = y ;
    }
    int getarea()
    {
        return length*height;
    }
}
class getrectangle
{
    public static void main(String args[])
    {
        rectangle a = new rectangle();
        System.out.println("first constructor area: "+a.getarea());

        rectangle b = new rectangle(5,4);
        System.out.println("first constructor area: "+b.getarea());

    }
}

---------------------------------END------------------------------

04.Extra problem
problem 04.1:
fibonacci_04_1.java : Write a program to generate the Fibonacci series
problem 04.2:
sort_arr_04_2.java : Write a program to generate the sorting order of array
problem 04.3:
class_rect_04_3.java : Design a class named Rectangel to represent a recrangle. The class contains:
-Two double data fields named width and height that specify the width and height of the rectangle. The default values are 1 for both width and height.
-A no-arg constructor that crates a default rectangle.
-a constructor that creates a rectangle with the specified width and height.
-A method named getArea()that returns the area of this rectangle.
-A method named getPrtimeter() that returns the perimeter.
Implement the class. Write a test program the creates two Rectangle obgects--one with width 4 and height 40 and the other with width 3.5 and height 35.9. Display the width,height,area and perimeter of each rectangle in this oreder.
problem 04.4
class_account_04_4.java : Design a class named Account that contains:
-A private int data field named id for the account(default 0).
-A private double data fiels named balance for the account(default 0).
-A pricate double data field named annualInterestRate that stores the current interest rate(default 0).Assume all accounts have the same interest rate.
-A private Data data field named dateCreated that stores the date when the account was created.
-A no-arg constructor that creates a default account.
-A constructor that creates an account with the specified id and initial balance
-The accessor and mutator methods for id,balance and annaulInterestRate.
-The accessor method for dateCreated.
-A method named getMonthlyInterestRate() that returns the monthly interest rate.
-A method named withdraw that withdraws a specified amounnt from the account.
-A method named deposit that deposits a specified amount to the account.
Implement the class. Write a test program that creates an Account object with an account ID of 1122,a balance of $20,000 and an annual interest rate of 4.5%. Use the withdraw method to withdraw $2,500 use the deposit method to deposite $3,000 and print the balance, the monthly interest, and the date when this account was created.
problem 04.4:
classrectangle_04_5.java : Create a class recangle. The class has two attributes, lenght and width. Each of which default to 0. It hs method that calculate the perimeter and area of the rectangel. It has set and get method for both length and width. The set method should verify that length and width are floating-point number larger thab 0.0 and less than 20.0.

day-03

darKLoin — Thu, 20 Oct 2022 13:34:18 +0000

DAY-03
Index
01.Break Lable
02.Continue Lable
03.Array
04.2D-Array
05.Class/Object
06.Extra problem
06.1: Write a JAVA program to find simple interest.
06.2: Definging a class called Student.Observe the members of the class i.e. the data and function.
06.3: Write the JAVA program that prompts the user for an integer and then prints out all prime numbers up to that integer.
06.4: Write a JAVA program that checks whether a given string is palindrome or not?
06.5: Write a JAVA program to fine the biggest & smallest number from the given array of 10 integers.
06.6: Write a JAVA program to sort given of 10 integers in ascending & descending order.
06.7: Write a JAVA program to delete an element from an array of 10 elements.
06.8: Write a JAVA program that prints transpose of given matrix.

---------------------------------START----------------------------
----------------------------------01------------------------------

Lable Break ~Lable Break: lable break means, coming out of a labled block of code OR braking the mentioned loop or block of code. it also work as a go to statement lable: is a identifire which identifies the some block of code. Systax: } { ...//statement }break lable; example: 01.1:write a simple program to show the use and working of'break lable;'

class lable
{
    public static void main(String args[])
    {
        boolean hell = true;
        first:
            {
                second: 
                    {
                        third:
                            {
                                System.out.println("in third block of code");
                                if(hell)
                                    break second;
                                System.out.println("after bresk second,, in third block of code.");
                            }
                        System.out.println("in second block of code.");
                    }
                System.out.println("in first block of code.");
            }

    }
}

example: 01.2: write a loop program to show the use of break lable.

class lablebreak
{
    public static void main(String args[])
    {
        first: for(int i = 0; i<100;i++)
                {
                    second: for(int j =10 ; j<100 ; i++ )
                            {
                                third: for(int k =0 ; k <5; k++)
                                        {
                                            ............................................................................
                                        }
                            }
                }
    }
}

~if lable break is not there in the block or the loop then it will give the error.
like

class errcheck
{
    public static void main(String args[])
    {
        fail: for(int i = 5 ; i<50 ;i++)
        System.out.println("hello this will excute with out loop.");

        second: for(int j =21; j<30; j++)
                {
                    if(j==25)
                        break fail;
                    System.out.println("after breaking fail.");
                }
    }
}

~ error will look like this

Main.java:11: error: undefined label: fail
                        break fail;
                        ^
1 error
exit status 1

---------------------------------END------------------------------
--------------------------------02--------------------------------

Lable continue
~ Lable Continue is work to skip some further steps of the loop or block of code in labled block.

example: 02.1: write a program to show the use of continue lable.

class contlable
{
    public static void main(String args[])
    {
    int i,j;
        first: for( i = 0 ; i<10 ; i++)
                {
                    second: for( j = 0 ; j<10 ; j++)
                            {
                                if(j>i)
                                {
                                    System.out.println(" ");
                                    continue first;
                                }
                                System.out.print(" "+i*j);
                            }
                }
        System.out.println("");
    }
}

---------------------------------END------------------------------
---------------------------------03-------------------------------

Array
~Array: it stores the data of same data type with consecutive order of memory.
~decleration:
DataType ArrayName[] = new dataType[Size];
int arr[] = new int[50];
int arr[] = {1,2,4,5,6,8,4,7,4};

example: 03.1: write a program to get the average double element of an array.

class arro
{
    public static void main(String args[])
    {
        double arr[] = {1.1,1.2,1.3,2.1,2.2,2.3,2.4};
        double result = 0, avg =0 ;
        for(int i = 0 ; i<arr.length; i++)
        {
            result = result+arr[i];
        }
        avg = result / arr.length;
        System.out.println("the average of given array is: "+avg);
    }
}

example: 03.2: write a program to get the average of an array.(size and element are input from user)

import java.util.Scanner;
class arr
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        int result =0;
        double avg = 0;
        System.out.println("Enter the size of array");
        int n = sc.nextInt();
        int arr[] = new int[n];
        System.out.println("Enter the element for the array");
        for(int i= 0 ; i<n; i++)
        {   
            arr[i] = sc.nextInt();
            result = result + arr[i];
        }
        avg = result/arr.length;
        System.out.println("The average of array is: "+avg);
    }
}

---------------------------------END------------------------------
---------------------------------04-------------------------------
04.2D-Array
~2D-Array: 2D-array are the same as the array but it stores the another dimension of the array
as shown in example:
example: 04.1: write a program to show the two dimensional array by taking input.

class 2darr
{
    public static void main(String args[])
    {
        int i,j,k=0;
        int arr[][] = new int[4][4];
        for(i = 0 ; i< 3 ; i++)
        {
            for(j =0 ; j<3 ; j++)
            {
                arr[i][j] = k ;
                k++;
            }
        }
        for(i =0 ; i<3 ; i++)
        {
            for(j =0 ; j <3 ; j++)
            {
                System.out.print(" "+arr[3][3]);
            }
                System.out.println("");
        }
    }
}

~we can decleare a 2-D in different ways
by taking input from user
by decleareing the different variable for different or outer position as declerared
int two[][] = new int[3][];
two[1] =new int[1];
two[2] = new int[2];
two[3] = new int[3];

by declearing the inner variable with respect of outer variable
int two[3][4] = new int[3][];
two[0] =new int[4];
two[2] =new int[4];
two[3] =new int[4];

---------------------------------END------------------------------
---------------------------------05-------------------------------
05.Class/Object
~there are two types of objects normally
1. tangible objects:- pen, desktop , bike, bottel.
2. intangible objects:- account , fee , air , marks.

~every objects have different states adn behaviours like
dog: states(name, color, bread,appetite) behaviour(bark,run,fetching)

class: it is the set of property behaviour which all entites in objects list.
include the all property(states, behaviour) in them for the similar objects.
it is also known as blueprint-n objects.

    the different propety(states,behaviour) is also known as instance variable(states) and instance function(behaviour)
    class is a logical entity and 
    objects is physical entity

for example 
    class laptop
    {
        float weight;
        int processer;
        float model;
        float color;
        float rate;
        //above all are the class member/instance variable/variable member

        void broucher()
        {
            float all = model+color+rate+weight;
            System.out.printnl(" "+all);
        } 
        //this is the class behacviour/instance function it uses the states of class
    }

    objects are created dynamicaly like lapotopIdentifire

    Creation of a class is a creation of a datatype and
    object creatation is creation of variable to use class datatype
    create a object as 
    laptop dell = new laptop();
    laptop hp = new laptop();
    laptop intel = new laptop();

    here 'laptop();' is work as a constructor

    object is also known as instance of a class

example: create a class and object

class laptop
{
float weight;
float model;
float color;
float rate;
void broucher()
{
float all = model+color+rate+weight;
System.out.printnl(" "+all);
}
}

class laptopIdentifier
{
    public static void main(String args[])
    {
        laptop obj1 = new laptop();
        obj1.weight = 230.44f; 
        obj1.model = 239944X; 
        obj1.color = #112233; 
        obj1.rate = 66000.0; 
        obj1.broucher();
        laptop obj2 = new laptop();
        obj2.weight = 465.44f; 
        obj2.model = 654167Y; 
        obj2.color = #458932; 
        obj2.rate = 85200.0f; 
        obj2.broucher();
        laptop obj3 = new laptop();
        obj3.weight = 850.00f; 
        obj3.model = 5448131A; 
        obj3.color = #789522; 
        obj3.rate = 239000.0; 
        obj3.broucher();
    }
}
    ```


---------------------------------END------------------------------
---------------------------------06-------------------------------

06.Extra problem
    ~problem
        06.1: Write a JAVA program to find simple interest.
    ~problem    
        06.2: Definging a class called Student.Observe the members of the class i.e. the data and function.
    ~problem
        06.3: Write the JAVA program that prompts the user for an integer and then prints out all prime numbers up to that integer.
    ~problem
        06.4: Write a JAVA program that checks whether a given string is palindrome or not?
    ~problem    
        06.5: Write a JAVA program to fine the biggest & smallest number from the given array of 10 integers.
    ~problem
        06.6: Write a JAVA program to sort given of 10 integers in ascending & descending order.
    ~problem
        06.7: Write a JAVA program to delete an element from an array of 10 elements.
    ~problem
        06.8: Write a JAVA program that prints transpose of given matrix.

day-02

darKLoin — Thu, 20 Oct 2022 13:33:32 +0000

DAY-02
Index
1.type conversion
1.1 Widening conversion
1.2 Narrowing conversion
2.conditional statement
2.1 If-else
2.1.1 arrange smaller to bigger
2.2 Loop
2.2.1 counting
2.3 Break/continue
2.3.1 nested loop testing and square
2.4 Switch
2.4.1 give the day
2.1.0 prime number between given range

---------------------------------START----------------------------
----------------------------------01------------------------------
1.type conversion/casting
1.1 Widening conversion
1.2 Narrowing conversion
~Type Conversion means converting the one data type to other data type
there are two type of conversion in JAVA
1.Widening Conversion
2.Narrowing Conversion
~1. Widening Conversion:--> {it can be done manually or automatically}
converting the smaller data type to bigger data type.
conversion follows the following order{smaller to bigger}
byte -> short -> int/char -> long -> float -> double
example:- byte a = 10;
int i = a; // byte converting to int {conversion is done manually}
long l = a+i; // int and byte converting to long{conversion is done automatically}

          int i = 20;
          float d = 44.1;
          doubel k = i+d;// 'k' gives the value in double formate

~NOTE:->> byte and short are always converted into int weather it int present or not.
~2. Narrowing Conversion:--> {it always done manually}
converting bigger data type to smaller data type
conversion follows the following order{bigger to smaller}
double -> float -> long -> int/char -> short -> byte
example:- int i = (int)(23.0/3.3)
short s = 32;
int s = 33.2;
float kk = (float)(i*s*d);
char i = (cahr) 65;
print'i';prnt 'kk';
---------------------------------END------------------------------
---------------------------------02-------------------------------
2.Conditional Statement
~2.1 If-else:--> if are used to check the condition, if 'if' condition is true than it will exucate the code of if block and if 'if' is wrong than the code of else block will exucate.
syntax is:
if(condition)
{
//block of code
}
else
{
//block of code
}
you can use many nested use of it as you want
example 2.1.1: 5,15,25 arrange them in decreasing order

    class arrange 
    {
        public static void main(String args[])
            {
                int a = 5 , b = 15 , c = 25;
                if(a<b)
                {
                    if(c<a)
                        System.out.println(" "+c+" "+a+" "+b);
                    else if(c>b)
                        System.out.println(" "+a+" "+b+" "+c);
                    else
                        System.out.println(" "+a+" "+c+" "+b);
                }
                else
                {
                    if(c<a)
                        System.out.println(" "+c+" "+a+" "+b);
                    else if(c>a)
                        System.out.println(" "+b+" "+a+" "+c);
                    else    
                        System.out.println(" "+b+" "+c+" "+a);
                }
            }
    }

--------------------------------2.1.1-----------------------------
2.2 Loop
There are three type of loops
for loop while loop do while loop

for loop : syntax.
        for(intialization ; condition ; changes)
        {
            //blocks of code
        }

example 2.2.1 : give the reverse counting using for loop

class forcount      
{
    public static void main(String args[])
    {
        for(int a = 10 ; a >= 0 ; --a)
        {
                System.out.print(" "+a);
        }
    }
}

while loop : syntax.
            while(condition)
            {
                //block of code
                changing statement;
            }

example 2.2.2 : give the reverse counting using while loop

class whilecount
{
    public static void main(String args[])
    {
        int a = 10;
        while(a > =0)
        {
            System.out.print(" "+a);
            --a;
        }
    }
}

do while loop : it will excuate once without checking any condition 
                syntax.
do
{
    //block of code
    changing statement;
}while(condition);

example 2.2.3 : give the use of do while loop using counting

class dowhilecount
{
    public static void main(String args[])
    {
        int a = 10;
        do
        {
            System.out.print(" "+a);
            --a;
        }while( a >= 0 );
    }

}

--------------------------------END-------------------------------
---------------------------------2.3------------------------------
2.3 Break/continue

Break: break statement are used to breaking loop or coming out from loop
Continue: continue statement are used to skip the loop

example 2.3.1 nested loop testing and square

class contbreak
{
    public static void main(String args[])
    {
        int a  , kk;
        for(int i = 10 ; i< i*i ; i++)// here it will run the infinte loop to break we will use the break condition
        {
            if(i< 15) 
                break;
            System.out.print(" "+i);
        }

        while(int i = 10)
        {
            for(int k = 0 ; k < k*k ; k++)
            {
                kk = k*i;
                System.out.println(" "+k*i);
                if(kk >20)
                    break;
            }
        }
    }

}

--------------------------------END-------------------------------
---------------------------------2.4------------------------------
2.4 Switch
Switch: switch statement are used to jump on the certain block of code by giveing choice to jump on that and then excuate that code and come out to the switch operation.

example 2.4.1 Give the day using switch operation

class theday
{
    public static void main(String args[])
    {
        int choice
        switch(4)
        {
        case '1' : System.out.println("Sunday");
            break;
        case '2' : System.out.println("Monday");
            break;
        case '3' : System.out.println("Tuesday");
            break;
        case '4' : System.out.println("wensday");
            break;
        case '5' : System.out.printnln("Thrusday");
                break;
        }
    }
}

--------------------------------END-------------------------------

2.5 problem:
2.5 : write a JAVA program to find the prime number between given range

import java.util.Scanner;
class primeno
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.println(" Enter the initial value for range: ");
        int low = sc.nextInt();
        System.out.println(" Enter the final value for range: ");
        int high = sc.nextInt();
        while(low<high)
        {
            boolean flag = false;
            for(int i = 2 ; i<i/2 ; i++)
            {
                if(low%i == 0)  
                {
                    flag = true;
                    break;
                }
            }           
            if(!flag)
                System.out.println(low+" ");
            ++low;
        }
    }
}

--------------------------------END-------------------------------
---------------------------------03------------------------------

Extra problem : ~problem: time_2_4_1.java{write a program to calculate current time in hrs,min,sec.(usign finction System.curretTimeMillis();)} ~problem: b_t_d_and_d_t_b_2_4_2.java{write a program that dose binary to decimal and decimal to binary} ~problem: factorial_2_4_3.java{write a program tha takes an integer n and calculate n! }

day-01

darKLoin — Thu, 20 Oct 2022 13:33:01 +0000

DAY-01
So in this class we are going to have some basic topic of JAVA with some program.
INDEX:-
01.set path
02.data type
03.identifiers
04.literals{last note}
05.special case float and long
06.operators types
06.01 airth06_01.java
06.02 relat06_02.java
06.03 Shift06_03.java
06.04 logical06_04.java
06.05 bitwise06_04.java
explaining the bitwise operation

--------------------------------------------------START-------------------------------------------------

---------------------------------------------------01---------------------------------------------------
01.SET PATH
~when we run the program on CMD then we have to set some specefic path to run jdk
or path to run jdk from CMD
~type this path in your CMD
'path-%path%;"C:\Program Files\Java\jdk-14.0.1\bin"';
or in your system it looks like
'path=%path%;"location_of_jdk-v_bin"';
~to check weather your java is working or not
~type - 'java' OR 'javac' in CMD
it will show some command realted to java if not then reapeat the process of installation of jdk.
---------------------------------------------------END--------------------------------------------------

---------------------------------------------------02---------------------------------------------------
02.DATA TYPE
~Primitive data type
byte short int long
float double
char
boolean
~Non-peimitive data type
String
Arrays
Classes

byte:size-1 byte
8-bit signed two's complement integer.
short:size-2 byte
16-bit signed two's complement integer.
int:size-4 byte
32-bit signed two's complement integer.
long:size-8 byte
64-bit signed two's compelment integer.

float:size-4 byte

32-bit
double:size-8 byte
64-bit

char:size-16-bit of Unicode character.

boolean:it has only two possible value as "Truth and False"

~Non-primitive data type will discuss later in chapter.
---------------------------------------------------END--------------------------------------------------
---------------------------------------------------03---------------------------------------------------
03.INDENTIFIERS
Idnetifiers: this are the symbolic name used for the identification.
~the first character must be a valid character as {letter,_,$}.
it should not be a number, symbol.
like this not this
my_account ^myaccount
_account 21hello
$money 64money
---------------------------------------------------END--------------------------------------------------
---------------------------------------------------04---------------------------------------------------
04.LITERALS
~it is notation that represent the fix value in a program. or constent.
---------------------------------------------------END--------------------------------------------------
---------------------------------------------------05---------------------------------------------------
05.special case float and long
~in other language we can simply decalre the float and long variable
but in java we have to add the first letter of our type at last of value of variable
like in JAVA in Other Language
float i = 124.15f; float i = 124.15;
long k = 6461761346; long int e = 4613164;
---------------------------------------------------END--------------------------------------------------
---------------------------------------------------06---------------------------------------------------
06.OPERATORS
~Airthmatic Operators:--->> +,-,,/,%,+=,-=,=,%=,/=.
~Relational Operators:--->> ==,!=,<,<=,>,>=.
~Logical Operators:--->> ||,&&,!
~Bitwise Operators:--->> &,|,~,^,
~Shift Operators:--->> <<,>>,>>>

~Airthmatic Operators
problem:
airth06_01.java{wirte java program showing the working of all Airthmatic Operators.}
~Relational Operators
problem:
relat06_02.java{wirte java program showing the working of all Relational Operators.}
~Shift Operators
problem:
Shift06_03.java{wirte java program showing the working of Shift Operators.}
~Logical Operators
problem:
logical06_04.java{wirte java program showing the working of all Logical Operators.}
~Bitwise Operators
problem:
bitwise06_05.java{write java program showing the working of all Bitwise Operators.}

factorial_2_4_4.java

darKLoin — Sat, 06 Nov 2021 14:54:53 +0000

//problem 2.4.3
        // factorial_2_4_3.java: write a program tha takes an integer n and calculate n! 
import java.util.Scanner;
class factorial_2_4_4
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int  fact = 1;
        if(num<1)
            System.out.println("Enter a valid number...");
        else if(num == 1)
            System.out.println("Factorial value of "+num+" 1");
        else
        {
            while(num>0)
            {
                fact = fact*num;
                num--;
            }
        }
        System.out.println("factorial value if"+fact);
    }
}

b_t_d_and_d_t_b_2_4_3.java

darKLoin — Sat, 06 Nov 2021 14:54:12 +0000

//problelm 2.4.2
        //b_t_d_and_d_t_b_2_4_3.java: write a program that dose binary to decimal and decimal to binary 
import java.util.Scanner;
class b_t_d_and_d_t_b_2_4_3
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the binary number: ");
         int binar = sc.nextInt();
        // System.out.println("Enter the decimal number: ");
        // int decimal = sc.nextInt();
        int bino = binar;
        int base = 1, num,rem, decino =0;
        while(bino > 0)
        {
            rem = bino % 10;
            decino = decino + rem*base ;
            bino = bino/10;
            base =  base *2;
        }
        System.out.println("Binary number is "+binar+"and \n Decimal number is "+decino);

    // decimal to binary
        System.out.println("\n\nEnter the decimal number: ");
        int decimal = sc.nextInt();
        int i =0 , deci;
        int binary[] = new int[16];
        deci = decimal;
        while(deci > 0)
        {
            binary[i++] = deci%2;
            deci = deci/2;
        }
        System.out.println("Decimal number is "+decimal+"and \n Binary number is ");
        for( i = i-1 ; i >= 0; i-- )
        {
            System.out.print(binary[i]);
        }

    }
}

time_2_4_1.java

darKLoin — Sat, 06 Nov 2021 14:53:14 +0000

//problem 2.4.1
        // time_2_4_1.java: write a program to calculate current time in hrs,min,sec.(usign finction System.curretTimeMillis();)

class time_2_4_1
{
    public static void main(String args[])
    {
        // System.out.println("Giving the current time in seconds: ");
        System.out.println((System.currentTimeMillis()));
        System.out.println("Time in hour "+(System.currentTimeMillis()/3600)+" : minute "+(System.currentTimeMillis()/60)+" : seconds "+System.currentTimeMillis());
    }
}

JAVA java Day-02

darKLoin — Sat, 06 Nov 2021 14:50:52 +0000

DAY-02

Index
1.type conversion
1.1 Widening conversion
1.2 Narrowing conversion
2.conditional statement
2.1 If-else
2.1.1 arrange smaller to bigger
2.2 Loop
2.2.1 counting
2.3 Break/continue
2.3.1 nested loop testing and square
2.4 Switch
2.4.1 give the day
2.1.0 prime number between given range

---------------------------------START----------------------------
----------------------------------01------------------------------
1.type conversion/casting
1.1 Widening conversion
1.2 Narrowing conversion
~Type Conversion means converting the one data type to other data type
there are two type of conversion in JAVA
1.Widening Conversion
2.Narrowing Conversion
~1. Widening Conversion:--> {it can be done manually or automatically}
converting the smaller data type to bigger data type.
conversion follows the following order{smaller to bigger}
byte -> short -> int/char -> long -> float -> double
example:- byte a = 10;
int i = a; // byte converting to int {conversion is done manually}
long l = a+i; // int and byte converting to long{conversion is done automatically}

          int i = 20;
          float d = 44.1;
          doubel k = i+d;// 'k' gives the value in double formate

~NOTE:->> byte and short are always converted into int weather it int present or not.
~2. Narrowing Conversion:--> {it always done manually}
converting bigger data type to smaller data type
conversion follows the following order{bigger to smaller}
double -> float -> long -> int/char -> short -> byte
example:- int i = (int)(23.0/3.3)
short s = 32;
int s = 33.2;
float kk = (float)(i*s*d);
char i = (cahr) 65;
print'i';prnt 'kk';
---------------------------------END------------------------------
---------------------------------02-------------------------------
2.Conditional Statement
~2.1 If-else:--> if are used to check the condition, if 'if' condition is true than it will exucate the code of if block and if 'if' is wrong than the code of else block will exucate.
syntax is:
if(condition)
{
//block of code
}
else
{
//block of code
}
you can use many nested use of it as you want
example 2.1.1: 5,15,25 arrange them in decreasing order

    class arrange 
    {
        public static void main(String args[])
            {
                int a = 5 , b = 15 , c = 25;
                if(a<b)
                {
                    if(c<a)
                        System.out.println(" "+c+" "+a+" "+b);
                    else if(c>b)
                        System.out.println(" "+a+" "+b+" "+c);
                    else
                        System.out.println(" "+a+" "+c+" "+b);
                }
                else
                {
                    if(c<a)
                        System.out.println(" "+c+" "+a+" "+b);
                    else if(c>a)
                        System.out.println(" "+b+" "+a+" "+c);
                    else    
                        System.out.println(" "+b+" "+c+" "+a);
                }
            }
    }

--------------------------------2.1.1-----------------------------
2.2 Loop
There are three type of loops
for loop while loop do while loop

*for loop* : syntax.
        for(intialization ; condition ; changes)
        {
            //blocks of code
        }

example 2.2.1 : give the reverse counting using for loop

class forcount      
{
    public static void main(String args[])
    {
        for(int a = 10 ; a >= 0 ; --a)
        {
                System.out.print(" "+a);
        }
    }
}

*while loop* : syntax.
            while(condition)
            {
                //block of code
                changing statement;
            }

example 2.2.2 : give the reverse counting using while loop

class whilecount
{
    public static void main(String args[])
    {
        int a = 10;
        while(a > =0)
        {
            System.out.print(" "+a);
            --a;
        }
    }
}

do while loop : it will excuate once without checking any condition 
                syntax.
do
{
    //block of code
    changing statement;
}while(condition);

example 2.2.3 : give the use of do while loop using counting

class dowhilecount
{
    public static void main(String args[])
    {
        int a = 10;
        do
        {
            System.out.print(" "+a);
            --a;
        }while( a >= 0 );
    }

}

--------------------------------END-------------------------------
---------------------------------2.3------------------------------
2.3 Break/continue

*Break*: break statement are used to breaking loop or coming out from loop
*Continue*: continue statement are used to skip the loop

example 2.3.1 nested loop testing and square

class contbreak
{
    public static void main(String args[])
    {
        int a  , kk;
        for(int i = 10 ; i< i*i ; i++)// here it will run the infinte loop to break we will use the break condition
        {
            if(i< 15) 
                break;
            System.out.print(" "+i);
        }

        while(int i = 10)
        {
            for(int k = 0 ; k < k*k ; k++)
            {
                kk = k*i;
                System.out.println(" "+k*i);
                if(kk >20)
                    break;
            }
        }
    }

}

--------------------------------END-------------------------------
---------------------------------2.4------------------------------
2.4 Switch
Switch: switch statement are used to jump on the certain block of code by giveing choice to jump on that and then excuate that code and come out to the switch operation.

example 2.4.1 Give the day using switch operation

class theday
{
    public static void main(String args[])
    {
        int choice
        switch(4)
        {
        case '1' : System.out.println("Sunday");
            break;
        case '2' : System.out.println("Monday");
            break;
        case '3' : System.out.println("Tuesday");
            break;
        case '4' : System.out.println("wensday");
            break;
        case '5' : System.out.printnln("Thrusday");
                break;
        }
    }
}

--------------------------------END-------------------------------

2.5 problem:
2.5 : write a JAVA program to find the prime number between given range

import java.util.Scanner;
class primeno
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.println(" Enter the initial value for range: ");
        int low = sc.nextInt();
        System.out.println(" Enter the final value for range: ");
        int high = sc.nextInt();
        while(low<high)
        {
            boolean flag = false;
            for(int i = 2 ; i<i/2 ; i++)
            {
                if(low%i == 0)  
                {
                    flag = true;
                    break;
                }
            }           
            if(!flag)
                System.out.println(low+" ");
            ++low;
        }
    }
}

--------------------------------END-------------------------------
---------------------------------03------------------------------

Extra problem :
~problem:
time_2_4_1.java{write a program to calculate current time in hrs,min,sec.(usign finction System.curretTimeMillis();)}

~problem:
b_t_d_and_d_t_b_2_4_2.java{write a program that dose binary to decimal and decimal to binary}

~problem:
factorial_2_4_3.java{write a program tha takes an integer n and calculate n! }