DEV Community: flevia g

FrameWork

flevia g — Tue, 05 Aug 2025 14:37:40 +0000

What is a Framework?

A framework is a foundation or skeleton for software development. It provides:

A standard way to build and deploy applications

Pre-written code for common tasks (e.g., logging, security, DB connection)

An enforced design pattern or architecture (like MVC, MVVM, etc.)

✅ Think of it like a "mold" or "blueprint" you must fit your code into.

Framework Architecture
Frameworks often follow certain design patterns. Common ones include:

MVC (Model-View-Controller) Model → handles data and business logic

View → displays the UI

Controller → handles user input and connects Model & View
📌 Used in: Spring MVC, Django, Laravel, Ruby on Rails

MVVM (Model-View-ViewModel) Used in front-end frameworks like Angular and in mobile apps (e.g., Android)

✅ Benefits of Using Frameworks
Speed: You don't build everything from scratch.

Consistency: Uniform code structure and behavior.

Scalability: Built-in support for complex features (routing, caching, ORM).

Security: Many frameworks come with protections (e.g., against SQL injection).

Community Support: Documentation, plugins, and help from other developers.

🔄 Real-time Example: Java Framework (Spring Boot)
Let’s say you're building a Banking Application.

Without a framework:

You write code to connect to the database manually

Set up your own logging, request handling, and user session

With Spring Boot:

You get REST APIs, logging, security, database connection, dependency injection—all pre-configured.

Using scanner class in datatypes

flevia g — Wed, 30 Jul 2025 12:47:03 +0000

package usingscan;
import java.util.Scanner;
public class Bank {

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter your first Number : ");
    int no1 = sc.nextInt();
    System.out.println("Enter your second Number : ");
    int no2 = sc.nextInt(); 
    System.out.println("Enter your third Number : ");
    int no3 = sc.nextInt();
    System.out.println(no1 +no2 +no3);

System.out.println("How would you improve this course?");   

String input = sc.nextLine();

    System.out.println("Your response:");

    System.out.println(input);

    sc.close();

System.out.println("Enter your first Number : ");
float no1 = sc.nextFloat();
System.out.println("Enter your second Number : ");
float no2 = sc.nextFloat(); 
System.out.println("Enter your third Number : ");
float no3 = sc.nextFloat();
System.out.println(no1 +no2 +no3);
}

System.out.println("Enter your mobile Number : ");
long no1 = sc.nextLong();
System.out.println("Enter your mobile Number : ");
long no2 = sc.nextLong(); 
System.out.println("Enter your mobile Number : ");
long no3 = sc.nextLong();
//System.out.println(no1 +no2 +no3);
}

System.out.println("Enter your first Number : ");
short no1 = sc.nextShort();
System.out.println("Enter your second Number : ");
short no2 = sc.nextShort(); 
System.out.println("Enter your third Number : ");
short no3 = sc.nextShort();
System.out.println(no1 +no2 +no3);
}

System.out.println("Enter your first Number : ");
double no1 = sc.nextDouble();
System.out.println("Enter your second Number : ");
double no2 = sc.nextDouble(); 
System.out.println("Enter your third Number : ");
double no3 = sc.nextDouble();
System.out.println(no1 +no2 +no3);
}

System.out.println("Enter your first Number : ");
byte no1 = sc.nextByte();
System.out.println("Enter your second Number : ");
byte no2 = sc.nextByte(); 
System.out.println("Enter your third Number : ");
byte no3 = sc.nextByte();
System.out.println(no1 +no2 +no3);
}

 //boolean

System.out.println("Enter your age: ");
 int age = sc.nextInt();  // user input as integer

 if (age >= 18) {
     System.out.println("You are eligible to vote.");
 } else {
     System.out.println("You are not eligible to vote.");
 }

 sc.close();
}

}

Find out max and min value in array

flevia g — Fri, 25 Jul 2025 11:59:16 +0000

package maxArray;

public class ArrayMax {

public static void main(String[] args) {
    int[] arr = { 5, 12, 3, 19, 8 };
    int max = 0;
    for (int i = 0; i < arr.length; i++) {
        if (max < arr[i]) {
            max = arr[i];
        }
    }
    System.out.println(max);

}

}

public class Minimum {

public static void main(String[] args) {
    int[] arr = { 10, 20, 30, 40, 5 };
    int min = arr[0]; // correct initialization

    for (int i = 0; i < arr.length; i++) {
        if (arr[i] < min) {
            min = arr[i];
        }
    }

    System.out.println("Minimum value: " + min);
}

}

String

flevia g — Fri, 18 Jul 2025 13:09:22 +0000

public class CharAt {

public static void main(String[] args) {
    String name = "flevia";

    char firstchar = name.charAt(0);
    char thirdchar = name.charAt(2);

    System.out.println("firstcharcter :" + firstchar);
    System.out.println("thirdcharcter :" + thirdchar);

}

}

public class EqualsinString {

public static void main(String[] args) {
    // TODO Auto-generated method stub
String correctusername = "admin";
String correctpassowrd = "admin123";

String inputusername = "admin";
String inputpassword = "admin123";

if (inputusername.equals(correctusername) && inputpassword.equals(correctpassowrd)) {
    System.out.println("Login Successful. Welcome " + inputusername + "!");
} else {
    System.out.println("Invalid credentials. Access Denied.");
}
}

public class Length {

   public static void main(String[] args){
        String name = "Flevia";
        int len = name.length();

        System.out.println("Length of the string: " + len);
    }

}

public class Lowercase {

public static void main(String[] args) {
       // Simulated user inputs
    String name = "FLEVIA";
    String city = "CHENNAI";

    // Convert both to uppercase using toUpperCase()
    String upperName = name.toLowerCase();
    String upperCity = city.toLowerCase();

    // Display standardized output
    System.out.println("Name: " + upperName);
    System.out.println("City : " + upperCity);

}
}

public class Replace {
public static void main(String[] args) {
// Original message from user
String message = "This movie is stupid and boring!";

    // Replace bad words using replace()
    message = message.replace("stupid", "****");
    message = message.replace("boring", "*****");

    // Display filtered message
    System.out.println("Filtered Message: " + message);
}

}

public class Substring {

public static void main(String[] args) {
       String date = "2025-07-16";  // Example: real-time input from a user or file

        // Extract parts using substring()
        String year = date.substring(0, 4);    // index 0 to 3
        String month = date.substring(5, 7);   // index 5 to 6
        String day = date.substring(8);        // index 8 to end

        // Print results
        System.out.println("Year: " + year);
        System.out.println("Month: " + month);
        System.out.println("Day: " + day);
    }


}

public class Trim {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    String name =" flevia ";
    System.out.println("beforetrim : " + name);

    String trimedname = name.trim();
    System.out.println("trim : " + trimedname);

}

}

public class Uppercase {
public static void main(String[] args) {
// Simulated user inputs
String name = "flevia g";
String city = "chennai";

// Convert both to uppercase using toUpperCase()
String upperName = name.toUpperCase();
String upperCity = city.toUpperCase();

// Display standardized output
System.out.println("Name (UPPERCASE): " + upperName);
System.out.println("City (UPPERCASE): " + upperCity);

}
}

Single inheritance with constructor and Method Hiding

flevia g — Sat, 12 Jul 2025 13:01:33 +0000

Single Inheritance:

package constructor;//Using single inheritance

public class Parentconstructor {

String name;
int empid;
public Parentconstructor(String name,int empid) {
    this.name=name;
    this.empid=empid;
    System.out.println("Employee Constructor Called");
    System.out.println("Name: " + name + ", ID: " + empid);

}

public static void main(String[] args) {



}

}

package constructor;

public class Childconstuctor extends Parentconstructor{

String techStack;

public Childconstuctor(String name, int empId, String techStack) {
    super(name, empId);  // Call to parent constructor
    this.techStack = techStack;
    System.out.println("Developer Constructor Called");
    System.out.println("Technology: " + techStack);
}

public static void main(String[] args) {
    Childconstuctor cc = new Childconstuctor("raj",1143,"JAVA");


}

}

Method Hiding:

package methodhiding;

public class Company {

public static void companyPolicy() {
    System.out.println("Company: General policy");
}


public static void main(String[] args) {
    // TODO Auto-generated method stub

}

}

package methodhiding;

public class Branchoffice extends Company{

public static void companyPolicy() {
    System.out.println("Branch Office: Specific policy");
}


public static void main(String[] args) {
    // TODO Auto-generated method stub
    Company cp = new Branchoffice();
   companyPolicy();  // Calls Company version (reference type)

    Branchoffice bh = new Branchoffice();
   companyPolicy();  // Calls BranchOffice version
}

}

Constructor

flevia g — Fri, 11 Jul 2025 13:29:13 +0000

What is constructor?
A constructor is a special method in Java that is used to initialize objects. It is called automatically when an object is created.

Key Features of Constructors:
Same name as the class

No return type (not even void)

Can be default (no arguments) or parameterized

Used to set initial values for object properties

Why Use Constructors?

To set default values

To create objects in a controlled way

To initialize instance variables while object creation

1.default constructor

public class Car {
Car() { // Constructor
System.out.println("Car object is created");
}

public static void main(String[] args) {
    Car myCar = new Car();  // Constructor is called here
}

}

2.Parameterized Constructor

public class Car {
String model;

Car(String carModel) {
    model = carModel;
}

public void display() {
    System.out.println("Car model: " + model);
}

public static void main(String[] args) {
    Car myCar = new Car("Honda City");
    myCar.display();
}

}

Single inheritance and dynamic binding

flevia g — Fri, 11 Jul 2025 13:21:40 +0000

package inheritance;

public class Parent {

String name;
int empId;

public static void main(String[] args) {
    Parent pr = new Parent();
    pr.displayInfo();
}

public void displayInfo() {
    System.out.println("Name: " + name);
    System.out.println("Employee ID: " + empId);
}

}

package inheritance;

public class Classparent extends Parent {
String programmingLanguage;

public static void main(String[] args) {
    Classparent dev = new Classparent();
    dev.name = "Flevia";
    dev.empId = 1025;
    dev.programmingLanguage = "Java";

    dev.displayDeveloperInfo();
}

void displayDeveloperInfo() {
    displayInfo(); // Calling parent class method
    System.out.println("Programming Language: " + programmingLanguage);
}

}

Dynamic Binding:

package Dynamicbinding;

public class Parent {

public static void main(String[] args) {

}

public void fatherjob() {

    System.out.println("IT");

}

public void motherjob() {

    System.out.println("designer");

}

}

package Dynamicbinding;

public class Childdynamic extends Parent{

public static void main(String[] args) {
    Parent cd = new Childdynamic();//dynamic binding
    Childdynamic vfr = new Childdynamic();
    cd.fatherjob();
    cd.motherjob();
    vfr.childeducation();

}

public void childeducation() {
System.out.println("Thirdstd");

}
}

Inheritance Concepts

flevia g — Thu, 03 Jul 2025 13:10:43 +0000

Inheritance

flevia g — Thu, 03 Jul 2025 13:08:40 +0000

GitHub and GitLab

flevia g — Tue, 01 Jul 2025 13:20:35 +0000

Real Time Java Program Using if and else if and Switch case

flevia g — Fri, 27 Jun 2025 08:24:35 +0000

public class RealtimeSwitchcase {

public static void main(String[] args) {
     Scanner scanner = new Scanner(System.in);

        // Display menu
        System.out.println("Welcome to ChatGPT Café!");
        System.out.println("1. Idli - ₹30");
        System.out.println("2. Dosa - ₹50");
        System.out.println("3. Pongal - ₹40");
        System.out.println("4. Exit");
        System.out.print("Please enter your choice (1-4): ");

        int choice = scanner.nextInt();

        switch (choice) {
            case 1:
                System.out.println("You ordered Idli. Please pay ₹30.");
                break;

            case 2:
                System.out.println("You ordered Dosa. Please pay ₹50.");
                break;

            case 3:
                System.out.println("You ordered Pongal. Please pay ₹40.");
                break;

            case 4:
                System.out.println("Thank you! Visit again.");
                break;

            default:
                System.out.println("Invalid choice. Please select a valid option.");
        }

        scanner.close();
    }
}

Using if and else if

public static void main(String[] args) {

            Scanner scanner = new Scanner(System.in);// take input from the user at runtime

            // Display menu
            System.out.println("Welcome to Simple Bank");
            System.out.println("1. Check Balance");
            System.out.println("2. Deposit Money");
            System.out.println("3. Withdraw Money");
            System.out.println("4. Exit");
            System.out.print("Please select an option (1-4): ");

            int option = scanner.nextInt();
            double balance = 1000.00; // Starting balance

            if (option == 1) {
                System.out.println("Your current balance is: ₹" + balance);
            } else if (option == 2) {
                System.out.print("Enter amount to deposit: ₹");
                double deposit = scanner.nextDouble();
                balance += deposit;
                System.out.println("Amount deposited successfully. New balance: ₹" + balance);
            } else if (option == 3) {
                System.out.print("Enter amount to withdraw: ₹");
                double withdraw = scanner.nextDouble();
                if (withdraw <= balance) {
                    balance -= withdraw;
                    System.out.println("Amount withdrawn successfully. New balance: ₹" + balance);
                } else {
                    System.out.println("Insufficient balance.");
                }
            } else if (option == 4) {
                System.out.println("Thank you for banking with us!");
            } else {
                System.out.println("Invalid option. Please try again.");
            }

            scanner.close();
        }

}

Java

flevia g — Thu, 26 Jun 2025 13:38:06 +0000