Learn Java by Starting from First Program - Hello World

It's always exciting to write your first program and execute it without error. In this post you will learn to write your first java program.

Pre-Requisite Softwares :

1. Java SE Development Kit or JDK  - It is generally a Java Software which you need to install on your system before writing any code in Java. And after installing java set Java Path in your environment variables.

• Download Latest Java Version from following link - Java Download

2. Java IDE or Text Editor - You need to have any text editor to write Java code. You can use anyone from following Netbeans, Intellij, Eclipse, Notepad or Notepad++ etc.

Creating Hello World Program

• Declare a class 'MyFirstProgram'
• Declare the main method public static void main()
• And print a string "Hello World" using System.out.println()

Hello World Program

// Class
class MyFirstProgram {
 
 // Main method
 public static void main(String[] args) {
  
  // Print Hello World
  System.out.println("Hello World");
 } 

}

Java Keywords used in 'Hello World' Program

• class keyword is used to declare a class.

• Public is an access modifier which defines main method's accessibility. Public means main method is global or accessible to all other classes in the project.

• static is a keyword in java, when static is used with any method then it is called static method. Static method can be called without creating the object of the class.

• main is the method name and also the execution point of any program. Main method is required to execute the program.

• String[] args is an array of string is basically for command line arguments.

• System.out.println() is used to print any statement. 
• System is a class
• out is the object of PrintStream class
• println() is method of PrintStream class

Run the First Program:

• If you are using Eclipse then you can run this program by just clicking the green play button displayed on the top bar. 
• Or right click anywhere in the class and click 'Run as Java Program'.

Output:

• Hello World - will be displayed in the console

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