Hello World - Java

A "Hello, World" program is a very simple program in the most programming languages. The "Hello, World" program shows the basic syntax of the programming language.

Text Editors

Text Editor is a computer program and available in every Operating System for writing plain text files. A plain text file can be a source code of a program.

• Windows Text editors- Notepad, Notepad++.
• Linux Text editors - Vi/Vim Editor, Gedit, Nano Editor.
• Mac Text editors - Brackets, TextWrangler, TextMate.

First program

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

Class - A class is the basic building block of the an object oriented programming language that contains methods, properties and inner blocks. A single source file can have multiple classes with unique class identifiers.

HelloWorld - HelloWorld is a unique class identifier. A source file can not have duplicate class names.

{ } curly brackets - It defines block of the code for classes, methods, blocks, decision statements and iterative statements.

public - Public is an access identifier that gives the public access to caller of main method within a class, within a package, outside of the package by subclass and outside of the package. 

static - static is a reserved keyword that is reserved for special purpose. static is used for calling a method by method name without creating an instance of the class.

void - void is a reserved keyword which is used in the signature of methods for telling that method returns nothing.

main - main is the name of method.

( ) parentheses - Parentheses are used to defined method signature with parameters.

System - System is a class; out - out is a static member of System class and have instance of PrintStream class; println - println is a method of PrintStream class.

; semicolon or terminator symbol - It is used to stop a statement in programming languages.

Steps to Write a Java program

1. Open text editor.
2. Write above program.
3. Save file to Desktop with "HelloWorld.java" file name.

Steps to Compile a Java program

1. Open command prompt.
2. Go to Desktop where you have saved your file.
3. write command to compile Java source file "javac HelloWorld.java".

Steps to Run a Java program

1. write a command to run program "java HelloWorld"