Creating Your First Application

Your first application, HelloWorldApp, will simply display the greeting "Hello World!". To create this program, you will:
Create an IDE project
When you create an IDE project, you create an environment in which to build and run your applications. Using IDE projects eliminates configuration issues normally associated with developing on the command line. You can build or run your application by choosing a single menu item within the IDE.
Add code to the generated source file
A source file contains code, written in the Java programming language, that you and other programmers can understand. As part of creating an IDE project, a skeleton source file will be automatically generated. You will then modify the source file to add the "Hello World!" message.
Compile the source file into a .class file
The IDE invokes the Java programming language compiler (javac), which takes your source file and translates its text into instructions that the Java virtual machine can understand. The instructions contained within this file are known as bytecodes.
Run the program
The IDE invokes the Java application launcher tool (java), which uses the Java virtual machine to run your application.