DEV Community: Ezhil Abinaya K

Python Pattern Program

Ezhil Abinaya K — Wed, 02 Sep 2026 13:43:05 +0000

for i in range(0, 5):
    for j in range(0, i+1):
        print("* ",end="")
    print()
o/p:
* 
* * 
* * * 
* * * * 
* * * * *

plaintext
2)

for i in range(5, 0, -1):
    for j in range(i):
        print("* ", end="")
    print()
o/p:
* * * * 
* * * 
* * 
*

Getter ,Setter in Java

Ezhil Abinaya K — Tue, 01 Sep 2026 15:01:33 +0000

In Java, Getter and Setter are methods used to protect your data and make your code more secure. Getter and Setter make the programmer convenient in setting and getting the value for a particular data type.

Getter in Java: Getter returns the value (accessors), it returns the value of data type int, String, double, float, etc. For the program's convenience, the getter starts with the word "get" followed by the variable name.

Setter in Java: While Setter sets or updates the value (mutators). It sets the value for any variable used in a class's programs. and starts with the word "set" followed by the variable name.

public class Student{
//private variables and getter setter method =pojo
private int id;
private String name;
private String course;
private int mark;
public Student(int id, String name, String course, int mark) {
        this.id = id;
        this.name = name;
        this.course = course;
        this.mark = mark;
    }
public static void main(String[] args){
Student s1 = new Student(101, "Ezhil", "Java", 85);
Student s2 = new Student(102, "Anban", "Python", 92);
}
public int getId() {
        return id;
 }

public void setId(int id) {
        this.id = id;
}

 public String getName() {
        return name;
 }

 public void setName(String name) {
        this.name = name;
 }

public String getCourse() {
        return course;
}

public void setCourse(String course) {
        this.course = course;
}

public int getMark() {
        return mark;
}

 public void setMark(int mark) {
        this.mark = mark;
}
}

Reference
https://www.geeksforgeeks.org/java/getter-and-setter-in-java/

Python Programs: Binary to Decimal and Spy Number

Ezhil Abinaya K — Sat, 29 Aug 2026 15:53:25 +0000

1) Binary to Decimal

binary=int(input(“enter a number:))
decimal=0
power=0
while binary>0:
          digit=binary%10
          decimal=decimal+digit * 2 ** power
          binary=binary//10
          power+=1
print(“decimal=”,decimal)

O/P:enter a number:1011
decimal = 11

2)Spy Number

num=int(input(“enter a number:))
sum_of_digit=0
product=1
while num>0:
          digit=num%10
          sum_of_digit+=1
          product*=1
          num//10
if sum_of_digit==product:
       print(“spy number”)
else:
      print(“not a spy number”)
o/p: enter a number:1124
spy number

Java Basic Concepts

Ezhil Abinaya K — Fri, 28 Aug 2026 14:15:01 +0000

Java this Keyword
The this keyword in Java refers to the current object in a method or constructor.The this keyword is often used to avoid confusion when class attributes have the same name as method or constructor parameters.
Java Classes/Objects
Java is an object-oriented programming language.Everything in Java is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.A Class is like an object constructor, or a "blueprint" for creating objects.
OOP stands for Object-Oriented Programming.

Procedural programming is about writing procedures or methods that perform operations on the data, while object-oriented programming is about creating objects that contain both data and methods.OOP is ideal for building scalable, reusable, and maintainable code.

Object-oriented programming has several advantages over procedural programming:

OOP provides a clear structure for the programs
OOP helps to keep the Java code DRY "Don't Repeat Yourself", and makes the code easier to maintain, modify and debug
OOP makes it possible to create full reusable applications with less code and shorter development time.

References
https://www.w3schools.com/java/java_oop.asp
https://www.w3schools.com/java/java_oop.asp

Methods in Java

Ezhil Abinaya K — Thu, 27 Aug 2026 13:59:55 +0000

Methods
A method is a block of code which only runs when it is called.You can pass data, known as parameters, into a method.Methods are used to perform certain actions, and they are also known as functions.
Why use methods? To reuse code: define the code once, and use it many times.
Create a Method
A method must be declared within a class. It is defined with the name of the method, followed by parentheses (). Java provides some pre-defined methods, such as System.out.println(), but you can also create your own methods to perform certain actions.

//Create a method inside Main://

public class Geeks
{
    // An example method
    public void printMessage() {
        System.out.println("Hello, Geeks!");
    }

    public static void main(String[] args) {

        // Create an instance of the class
        // containing the method
        Geeks obj = new Geeks();

        // Calling the method
        obj.printMessage(); 
    }
}
O/P:
Hello, Geeks!

Syntax of Java Methods

returnType methodName(parameters) {
  // method body
 return value; // optional (only if returnType is not void)
}

Method Overloading
Same method name with different number of arguments or with diiferent type of arguments are called method overloading or compile time polymorphism.

public class Supermarket
{
//fields
static String supermarketname="D-Mart";
static int supermarketdoorno=13/1;
//non-static variables
String things;
int price;
int discount;
public Supermarket(String things,int price){
this.things=things;
this.price=price;
}
public Supermarket(String things,int price,int discount){
this.things=things;
this.price=price;
this.discount=discount;
}
public static void main(String[] args)
{
//object
Supermarket things1=new Supermarket("Rosemilk",30);
Supermarket things2=new Supermarket("Galaxychocky",50);
Supermarket things3=new Supermarket("Kinderjoy",50,20);
things1.buy();
things1.buy(10);
 System.out.println(Supermarket.supermarketname);
 System.out.println(Supermarket.supermarketdoorno);
 System.out.println(things1.things);
 System.out.println("₹" + things1.price);
 System.out.println(things2.things);
 System.out.println("₹" + things2.price);
 System.out.println(things3.things);
 System.out.println("₹" + things3.price);
  System.out.println(things3.discount + "%" );
 }
 //method overloading
 public void buy(){
 System.out.println("buy-method");
 }
 public void buy(int account){
 System.out.println("buy-method-one-argument");
 }
}
o/p:
buy-method
buy-method-one-argument
D-Mart
13
Rosemilk
₹30
Galaxychocky
₹50
Kinderjoy
₹50
20%

References
https://www.w3schools.com/java/java_methods.asp
https://www.geeksforgeeks.org/java/methods-in-java/

Constructors in Java

Ezhil Abinaya K — Wed, 26 Aug 2026 14:39:19 +0000

Java Constructors
A constructor in Java is a special member that is called when an object is created. It initializes the new object’s state. It is used to set default or user-defined values for the object's attributes

A constructor has the same name as the class.
It does not have a return type, not even void.
It can accept parameters to initialize object properties.

public class Home
{
//fields
static String homename="Ezhil";
static int homeAge=15;
//non-static variables
String name;
int age;
//constructor
public Home(String name,int age){
this.name=name;
this.age=age;
}

public static void main(String[] args)
{
//object
Home person1=new Home("Anban",30);
Home person2=new Home("Karthikeyan",55);
 System.out.println(Home.homename);
 System.out.println(Home.homeAge);
 System.out.println(person1.name);
 System.out.println(person1.age);
 System.out.println(person2.name);
 System.out.println(person2.age);
 }
}
O/P:
Ezhil
15
Anban
30
Karthikeyan
55

public class Supermarket
{
//fields
static String supermarketname="D-Mart";
static int supermarketdoorno=13/1;
//non-static variables
String things;
int price;
int discount;
public Supermarket(String things,int price){
this.things=things;
this.price=price;
}
public Supermarket(String things,int price,int discount){
this.things=things;
this.price=price;
this.discount=discount;
}
public static void main(String[] args)
{
//object
Supermarket things1=new Supermarket("Rosemilk",30);
Supermarket things2=new Supermarket("Galaxychocky",50);
Supermarket things3=new Supermarket("Kinderjoy",50,20);
 System.out.println(Supermarket.supermarketname);
 System.out.println(Supermarket.supermarketdoorno);
 System.out.println(things1.things);
 System.out.println("₹" + things1.price);
 System.out.println(things2.things);
 System.out.println("₹" + things2.price);
 System.out.println(things3.things);
 System.out.println("₹" + things3.price);
  System.out.println(things3.discount + "%" );
 }
}
0/P:
D-Mart
13
Rosemilk
₹30
Galaxychocky
₹50
Kinderjoy
₹50
20%

Reference
https://www.geeksforgeeks.org/java/constructors-in-java/

Java DataTypes

Ezhil Abinaya K — Tue, 25 Aug 2026 13:28:19 +0000

Object-Oriented Programming (OOP) is a programming paradigm based on the concept of objects that contain data (fields) and behavior (methods). It focuses on designing software that closely represents real-world entities.
Characteristics of OOP

Java Data Types
Java data types define the type of data a variable can store in a program. They help the compiler allocate memory efficiently and ensure type safety. Java provides two main categories: primitive and non-primitive data types.

Class
A Class in Java is a blueprint or template used to create objects. It defines the properties (data) and behaviors (methods) that objects of that class will have.

A class is a user-defined data type.
It contains variables (fields) and methods.
Multiple objects can be created from a single class. Example: A Car represents a class (blueprint), while BMW, Mercedes, and Audi represent objects (instances) created from that class. Object An Object in Java is an instance of a class that represents a real-world entity. It is used to access the variables and methods defined inside a class. Example: Dog is a class, Tommy is an object of that class.

public class Home
{
static String name="Ezhil";
static int homeAge=15;
public static void main(String[] args)
{
 System.out.println(Home.name);
 System.out.println(Home.homeAge);
 }
}
O/P:
Ezhil
15

References
https://www.geeksforgeeks.org/java/object-oriented-programming-oops-concept-in-java/
https://www.geeksforgeeks.org/java/java-data-types/

Introduction to Java

Ezhil Abinaya K — Mon, 24 Aug 2026 14:14:01 +0000

Java
Java is a high level programming language.It was introduced by James Gosling in 1995. It is a widely used programming language for building web, desktop, mobile, and enterprise applications. It is known for its simple syntax, portability, and powerful features that make development easier and more secure.
Why Java was Introduced?
A video was played in our machine (laptop/system).Where did played video ?In our machine memory run that video . So, before memory accesed it first access by processor and then goes to memory.Here, c++ programming language needs a separate intermediator(Translator) but called as compiler to convert machine language (binary 0,1).Here, translation work was done but why named as compiler? There are 2 types of translator.
1. Compiler.
2.Interpreter.
Compiler: It reads whole program and then speak with computer.
Interpreter: It reads line by line.
If c++ what issue faced? C++ did not compile for the each different machine.If each machine has different platforms so, different machines needs compiler.If issue was faced in 1990's and in 1992 mid or end all teams works and introduced JAVA.Initially, it was named OAK at that time, faced some issue so JAVA name was come.
Java Architecture
Java Code didnt convert directly machine language. It first converts into byte code(.class).Byte code compilation was done by Java Development Kit(JVK).JVK is a set of software. Before byte code change , the program has no error after only it compile byte codes..class byte codes line by line reads and converts into binary (machine language).This process is called Java In Time Compiler (JIT).Machine level language is a low level language. Java is a high level language.The JIT and JDK has no connection so thats only tell java is a platform independent. Every machine has same byte code. JIT didnt give directly to the machine.It clones environment like machine .That's called Java Virtual Machine (JVM).
JAVA ---> Byte ---> 0,1(JRE)

public class Home
{
public static void main(String[] args)
{
 System.out.println("Hello World");
 }
}
Hello World

Features of Java

Object-Oriented Programming (OOP) supports modular and reusable code using classes and objects.
Platform Independence allows Java programs to run on any operating system with a JVM.
Robust and Secure provides strong memory management, exception handling, and built-in security features.
Multithreading and Concurrency enables multiple tasks to execute simultaneously for better performance.
Rich API and Standard Libraries offer extensive built-in libraries for common programming tasks.
Frameworks for Enterprise and Web Development support building enterprise applications, web applications, and REST APIs.
Open-Source Libraries provide a large ecosystem of libraries to extend functionality.
Maintainability and Scalability make Java applications easy to maintain, enhance, and scale as requirements grow.

Reference
https://www.geeksforgeeks.org/java/introduction-to-java/

Python Program for factorial and counting the digits

Ezhil Abinaya K — Fri, 21 Aug 2026 14:45:20 +0000

1) factorial program: expected: Input: n = 6
Output: 720
Explanation: 6! = 6 × 5 × 4 × 3 × 2 × 1 = 720

n = 6
if n < 0:
    print("Factorial is not defined for negative numbers")
else:
    f = 1
    for i in range(1, n+1):
        f *= i
    print(f)
#720

if n < 0: checks for negative numbers; factorial isn’t defined.
f = 1: initializes the product.
for i in range(1, n+1): f *= i multiplies all numbers from 1 to n iteratively.
2) Python program for counting the digits in a number.

num=int(input("Enter number: "))
count=0
i = num
# count the digits
while(i>0):
    count=count+1
    i=i//10
print(f"The number of digits in {num}:",count)
#Enter number:8516
The number of digits in 8516: 4

PostMan API Testing

Ezhil Abinaya K — Thu, 20 Aug 2026 13:53:58 +0000

Postman
Postman is a widely used API testing tool that helps developers and testers send requests, validate responses, and automate API workflows efficiently.

Simplifies API testing with an easy-to-use interface.
Supports CRUD operations such as GET, POST, PUT, and DELETE.
Allows automation of API tests using JavaScript scripts.

CRUD Operations with Postman
Create: Adds new data (POST).
Read: Retrieves existing data (GET).
Update: Modifies existing data (PUT).
Delete: Removes data (DELETE).
Sending a Post Request
A POST request is used to send data to the server, such as submitting a form. In Postman, choose POST, go to the Body tab, and enter the required data in form-data or raw JSON format. After clicking Send, the server responds to confirm whether the data was successfully received.

Change the HTTP method of the next request to POST. In Postman, use the Body tab instead of the Params tab.This is used to send the form data with the required key-value pairs.

References
https://www.geeksforgeeks.org/software-engineering/basics-of-api-testing-using-postman/
https://www.geeksforgeeks.org/web-tech/introduction-postman-api-development/

Postgresql Joins

Ezhil Abinaya K — Wed, 19 Aug 2026 13:44:06 +0000

PostgreSQL JOINS
A JOIN clause is used to combine rows from two or more tables, based on a related column between them.Let's look at a selection from the products table:

 product_id |  product_name  | category_id
------------+----------------+-------------
         33 | Geitost        |           4
         34 | Sasquatch Ale  |           1
         35 | Steeleye Stout |           1
         36 | Inlagd Sill    |           8

Then, look at a selection from the categories table:

category_id | category_name
-------------+----------------
           1 | Beverages
           2 | Condiments
           3 | Confections
           4 | Dairy Products

Notice that the category_id column in the products table refers to the category_id in the categories table. The relationship between the two tables above is the category_id column.

Then, we can create the following SQL statement (with a JOIN), that selects records that have matching values in both tables:

SELECT product_id, product_name, category_name
FROM products
INNER JOIN categories ON products.category_id = categories.category_id;

Result
 product_id |  product_name  | category_name
------------+----------------+----------------
         33 | Geitost        | Dairy Products
         34 | Sasquatch Ale  | Beverages
         35 | Steeleye Stout | Beverages
         36 | Inlagd Sill    | Seafood

Reference
https://www.w3schools.com/postgresql/postgresql_joins.php

Integration Testing

Ezhil Abinaya K — Tue, 18 Aug 2026 13:40:31 +0000

Will developer do testing?
Yes,developer done testing called unit test only.
Unit Testing
Unit Testing is a software testing method in which individual units or components of a software application (such as functions, methods, or classes) are tested in isolation to verify that they work correctly as expected.It helps find and fix defects at the very beginning of the development cycle, reducing the cost and effort of debugging later.
Aftet test case writing testers what can do?
After test case writing testers will do preparation for test environment or test bed preparation. Test bed preparation is nothing but Create a environment for OS, browsers, hardware, network, db service etc..
Integration Testing
Integration testing is done by testers.It is nothing but combining more than one unit and testing. It has 2 areas top down approach and bottom up approach.
Integration testing is a software-testing approach in which various application components or modules are joined and tested to evaluate how well they work together.
Real-World Example
E-Commerce Website: Integration testing ensures different modules of an online shopping platform—product catalog, shopping cart, payment gateway, and user accounts work together correctly.
Top Down Approach
Top-Down Testing is an incremental integration testing approach in which testing begins with high-level modules and gradually moves down to lower-level modules. It verifies system functionality by integrating components from top to bottom through the control flow.
Example:
First we test the sign up - after sign up we test the sign in then we test the sign out.After sign out the sign in function work well or not to be test .If password will be forgot that function work well or not to be test.This example will be test in reverse is called Bottom up approach.
Bottom Up Approach
In Bottom-Up Integration Testing, lower-level modules are tested first, followed by gradual integration of higher-level modules.
Stubs and Drivers
Stubs is a dummy temporary software (like for sign up)will be given to tester.It is used in both the approach but mainly focuses on top down approach. It is known as called program.
Driver is also a dummy temporary software which drives the other module.It is used in both the apporach but mainly focuses on bottom up approach.It is known as calling program.
References
https://www.geeksforgeeks.org/software-testing/software-engineering-integration-testing/
https://www.geeksforgeeks.org/software-engineering/steps-in-top-down-integration-testing/