First Java Program by ocec

First Java Program : 

In this section, we will learn how to write the simple program of Java. We can write a simple hello Java program easily after installing the JDK.

To create a simple Java program, you need to create a class that contains the main method. Let's understand the requirement first.

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

Now, let me explain what each part of this code does:

1. `public class HelloWorld { ... }`: This line defines a class named `HelloWorld`. In Java, every program must have at least one class, and the name of the file containing the code must match the name of the public class.

2. `public static void main(String[] args) { ... }`: This line defines a method named `main`. In Java, the `main` method is the entry point for any program. It's where the program starts executing. The `public`, `static`, and `void` keywords have specific meanings:
  - `public`: This keyword indicates that the method can be called from anywhere.
  - `static`: This keyword indicates that the method belongs to the class itself, rather than to instances of the class.
  - `void`: This keyword indicates that the method does not return any value.

3. `System.out.println("Hello, World!");`: This line uses the `System.out.println()` method to print the string `"Hello, World!"` to the console. The `System.out` object represents the standard output stream, typically the console or terminal where you see text output. The `println()` method is used to print a string followed by a newline character, so each call to `println()` starts on a new line.

When you run this program, it will output:

Hello, World!
 

This simple program demonstrates the basic structure of a Java program and how to output text to the console.