Welcome back to Java Code Online. Java Source Code is simply the code you write in Java. There are many editors available right now for writing Java Code. The most simple editor for writing Java Source Code is the "Notepad" provided by Windows.
There are many pioneers in Java Technology, in industry major of the Java applications are written in Eclipse. One more tool that is becoming very famous recently is WSAD(Web Sphere Application Developer) by IBM. This tool is really good.
I have been using this tool for a long time now, and believe me it meets all your requirements for Java coding. The tools provided in WSAD are awesome. If you have a chance then do put your hands on this tool. WSAD is built on Eclipse itself, so having a knowledge of Eclipse will be very beneficial in using WSAD for writing Java Source Code.
By default the Java Source Code files have .java extension. So that's it for now guys. If you liked this article then do leave a comment. For more info on Java keep buzzing Java Code Online.