Start java program from Hello World

The Hello world Java program has a main function, in which an object of OutputStream to print string (Hello World) from program to computer monitor.

Java main function

• A Java program or application must have a main function.
• The Java interpreter starts execution from the main function.
• The main function must be defined with the following keywords.
  1. void - specify return type of the function. the main function's return-type must be void (no return value)
  2. static - it specify that the main function must be accessed class-name. (The Java interpreter does not need to initialize an object to the class having the main function).
  3. public - it specify that the main function can be accessed from outside of the class.
• The file having the main function should be saved as the class-name.
• System - A final class provides system properties, process features and I/O objects.
• out - An object of the OutputStream provides print member functions to connect output device.
• println - A member function the object, out prints string (message) on the output device (default computer monitor).

Jave program - Hello World

The Hello World program prints the message "Hello World" on display screen

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

 

Output

  Hello World