Java - Hello World Program

Printing "Hello World" on the output screen (console) is the first program in Java and other programming languages. This tutorial will teach you how you can write your first program (print "Hello World" program) in Java programming.

Java program to print "Hello World"

Java program to print "Hello World" is given below:

public class MyFirstJavaProgram {

   /* This is my first java program.
    * This will print 'Hello World' as the output
    */

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

Steps to Write, Save, and Run Hello World Program

Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps −

• Open notepad and add the code as above.
• Save the file as − "MyFirstJavaProgram.java".
• Open a command prompt window and go to the directory where you saved the class. Assume it's C:\.
• Type 'javac MyFirstJavaProgram.java' and press enter to compile your code. If there is no error in your code, the command prompt will take you to the next line (Assumption − The path variable is set. Learn: Java Envionment Setup).
• Now, type 'java MyFirstJavaProgram' to run your program.
• You will be able to see "Hello World" printed on the screen.

Output

C:\> javac MyFirstJavaProgram.java
C:\> java MyFirstJavaProgram
Hello World

Explanation of Hello World Program

As we've successfully printed Hello World on the output screen. Let's understand the code line by line.

1. Public Main Class

public class MyFirstJavaProgram {

This line is creating a new class MyFirstJavaProgram and being public, this class is to be defined in the same name file as MyFirstJavaProgram.java. This convention helps Java compiler to identify the name of public class to be created before reading the file content.

2. Comment Section

/* This is my first java program.
* This will print 'Hello World' as the output
*/

These lines being in /* */ block are not considered by Java compiler and are comments. A comment helps to understand program in a better way and makes code readable and understandable.

3. Public Static Void Main

public static void main(String []args) {

This line represents the main method that JVM calls when this program is loaded into memory. This method is used to execute the program. Once this method is finished, program is finished in single threaded environment.

4. Keywords Used

Let's check the purpose of each keyword in this line.

• public − defines the scope of the main method. Being public, this method can be called by external program like JVM.
• static − defines the state of the main method. Being static, this method can be called by external program like JVM without first creating the object of the class.
• void − defines the return type of the main method. Being void, this method is not returning any value.
• main − name of the method
• String []args − arguments passed on command line while executing the java command.

5. System.out.println() Method

System.out.println("Hello World"); // prints Hello World

System.out represents the primary console and its println() method is taking "Hello World" as input and it prints the same to the console output.