Java “Hello, World!” Program

A “Hello, World!” is a Basic program in Java that outputs Hello, World! on the screen. Since it’s a very simple program, often used to introduce a new programming language to a newbie.

So Let’s explore how Java “Hello, World!” program.

Java programming code : 

// Your First Program

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

If you have copied the exact code, you need to save the file name as HelloWorld.java. It’s because the name of the class and filename should be same in Java.

Output will be:

Hello, World!

The process of Running a Java program can be simplified in three steps:

• Create the program by typing it into a text editor and saving it to a file – HelloWorld.java.
• Compile it by typing “javac HelloWorld.java” in the terminal window.
• Execute (or run) it by typing “java HelloWorld” in the terminal window.

 

How Java “Hello, World!” Program Works?

1. // Your First ProgramIn Java, any line starting with // means it is a comment. Comments are intended for person reading the code and to better understand the intent and functionality of the program. It is completely ignored by the Java compiler (an application that translates a Java program to bytecode which computer can execute).
2. class HelloWorld { ... }In Java, every application Should begins with a class definition. In our java program, HelloWorld is the name of the class, and the class definition is:

   class HelloWorld {
   ... .. ...
   }

   just for now remember that, every Java application has a class definition, and the name of class should match the filename in Java.

3. public static void main(String[] args) { ... }This is the main method. Every application in Java must contain a main method. The Java compiler starts executing the code from the main method.

   public static void main(String[] args) {
   ... .. ...
   }

4. System.out.println("Hello, World!");The following code prints the string Written inside quotation marks Hello, World! to standard output (your screen). Notice, this statement is inside the main function, which is inside the class definition.