Thursday, December 26, 2019

First Java program to print "Hello World"

First Java program

This is our first program in Java. In this program, we will print “hello world” message on the screen and see how the basic Java program is compiled and executed by Java. This has been a tradition to create the first program in any programming language which prints hello world on the screen so we will do the same and make the same program. Java is an object-oriented programming language, which is widely used all over the world by the majority of developers to develop large web and desktop applications. Java is also a pioneering technology in the industry that is used for mobile(Android) app development.

The "Hello World" program


Write the following code in your favorite editor and compile it.



Compile the program using the following command
javac HelloWorld.Java

And execute your program using the command

java HelloWorld



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



Structure of "Hello World" Program



"Hello World" program in Java
"Hello World" program in Java

Java Keywords


A keyword is a reserved word or literal having some special meaning to perform or represent something in a programming language. The keywords can't be used as identifiers or variable names in a Java Program.
Following is the list of the Java keywords.

Java Keywords

abstract continue for new switch
assert*** default goto* package synchronized
boolean do if private this
break double implements protected throw
byte else import public throws
case enum**** instanceof return transient
catch extends int short try
char final interface static void
class finally long strictfp** volatile
const* float native super while



*
not used
** added in 1.2
*** added in 1.4
**** added in 5.0



Running a Java Program with command-line arguments


1. write a program and compile with the command
javac HelloWorld.Java


2. Execute your program using the command
java HelloWorld Java Python

/****Running with command-line arguments**********/
public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello "+args[0]);
        System.out.println("Hello "+args[1]);
    }
}

Output:

Hello Java
Hello Python





Video Example