Java-Tutorial-2-Java Program Hello World

Java Program Hello World

To Execute Below Program; put this code in text file. Save as File””


Open Cmd prompt.

Go to the respective folder or directory by CD command and execute below command for compile.

First code need to be compiled. Enter Command.

java <name_of_source_file>.java

Once Compilation is done new files with “.class extensions” will be created.

For Execution Run these Class file with Command:

java <name_of_class_file>

Two step Process:

  • Compile code
  • Execute code.
To compile: javac
To execute: java Simple

What happens at compile time?

At compile time, java file is compiled by Java Compiler (It does not interact with OS) and converts the java code into bytecode.

compilation of simple java program


Understanding first java program

Let’s see what is the meaning of class, public, static, void, main, String[], System.out.println().

  • class keyword is used to declare a class in java.
  • public keyword is an access modifier which represents visibility, it means it is visible to all.
  • static is a keyword, if we declare any method as static, it is known as static method. The core advantage of static method is that there is no need to create object to invoke the static method. The main method is executed by the JVM, so it doesn’t require to create object to invoke the main method. So it saves memory.
  • void is the return type of the method, it means it doesn’t return any value.
  • main represents startup of the program.
  • String[] args is used for command line argument.
  • System.out.println() is used print statement.