DEV Community: Udaya M

Java program

Udaya M — Thu, 21 Aug 2025 08:39:04 +0000

Program 1: Print 1 1 1 1 1
public class Program1 {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
System.out.print("1 ");
}
}
}
Program 2: Print 1 2 3 4 5
public class Program2 {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
System.out.print(i + " ");
}
}
}
program 3:Print 1 3 5 7 9
public class Program3 {
public static void main(String[] args) {
for (int i = 1; i <= 9; i += 2) {
System.out.print(i + " ");
}
}
}
Program 4: Print 3 6 9 12 15
public class Program4 {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
System.out.print(3 * i + " ");
}
}
}
Program 5: Multiples of 3 and 5 (first 10 numbers)
public class Program5 {
public static void main(String[] args) {
int count = 0;
int num = 1;
while (count < 10) {
if (num % 3 == 0 && num % 5 == 0) {
System.out.print(num + " ");
count++;
}
num++;
}
}
}

Constructor in Java:

Udaya M — Thu, 17 Jul 2025 07:37:39 +0000

Constructor:

Constructor is a special method used to initialize objects. It is called automatically When a object of a class is created.

Characteristics:

Constructor name must be same as class name
It has no return type not even void
It is automatically invoked when the object is created.
Can be overloaded i.e multiple constructors in one class with different parameters.

Types of constructors:

           Two Types of Constructors

1.Default Constructor

     A Constructor with no parameters.
     Provided automatically by the constructor if no constructor is written.

Program For Defult:

class Vehicle {
  Vehicle() {
    System.out.println("Car is created");
  }

  public static void main(String[] args) {
    Vehicle  v = new Vehicle();  // Constructor is called
  }
}

output:
car is created.

Parameterised Constructor:

Constructor that accepts arguments to initialize the object with custom values.

Program for Parametersized:

class Student {
  String name;
  int age;
  Student(String n, int a) {
    name = n;
    age = a;
  }
void display() {
    System.out.println(name + " " + age);
  }

  public static void main(String[] args) {
    Student s1 = new Student("Ram", 20);
    s1.display();
  }
}

Output:

Ram 20

Introduction to React:

Udaya M — Fri, 13 Jun 2025 06:46:32 +0000

Introduction to React: The Beginner's Guide
Welcome to the exciting world of React.js! Whether you’re a seasoned developer exploring new frameworks or a beginner stepping into the world of web development, React offers a robust and intuitive way to build dynamic user interfaces. This blog introduces React and explains why it has become one of the most popular libraries for web development.

What is React.js?
React.js, or simply React, is a JavaScript library developed by Facebook for building fast and interactive user interfaces. It is widely used for developing single-page applications (SPAs), mobile apps (with React Native), and even complex enterprise applications.

Key Features of React:
Declarative: React makes it easy to create interactive UIs. Developers simply declare what they want, and React efficiently updates the necessary changes.

Component-Based: React encourages splitting the UI into small, reusable pieces called components.

Virtual DOM: By updating only what’s necessary in the DOM, React ensures high performance.

Unidirectional Data Flow: Data flows in one direction, making the application more predictable and easier to debug.
Why Learn React?

High Demand in the Job Market
React developers are highly sought after, with countless companies relying on React for their front-end needs.
Reusability and Scalability
React’s component-based architecture allows developers to reuse code, reducing redundancy and improving scalability.
Active Community
With millions of developers using React, you’ll find extensive documentation, tutorials, and community support.
Ecosystem
React integrates seamlessly with tools like Redux, Next.js, and more, making it versatile for various development needs.

How React Works

Components
In React, the UI is made up of small, independent pieces called components. Each component represents a part of the UI and can be reused multiple times.
Example:
function Welcome() {
return

Welcome to React!
; }
JSX
React uses JSX, a syntax extension for JavaScript that allows you to write HTML-like code inside JavaScript.
Example:
const element =

Hello, JSX!
;
Virtual DOM
Instead of updating the entire web page, React creates a lightweight copy of the DOM (Virtual DOM) to determine the minimal updates needed for efficiency.