The Java programming language is one of the true success stories of the internet age. Developed by Sun Microsystems in 1995, it has been a regular feature of the net for the past 13 years and is still going strong. Last year however, perhaps sensing that Java may not continue to enjoy it's popularity indefinitely, Sun opened up its source code and made all Java technologies free under the GNU licence.
Of course the obvious starting point for any developer is to ensure that they've got Java installed to test all your nifty applets that you're going to create. The next thing you'll need is a decompiler such as Cavaj Java Decompiler that puts together all your coding and allows you to view other Java source code. Note that you don't have to have Java installed to use this program either. Alternatively, DJ Java Compiler is much simpler and can export your code to limited file formats but it lacks many of the advanced features of the former.
If you're completely new to Java programming however, you may find something easier such as Java Launcher more user-friendly as it takes all the jargon and complex aspects of a decompiler and puts them in layman's terms. If you're at a more advanced stage however, then you'll need a few more specialist tools to enhance your programming. Finally, it's always a good idea to have a hard copy of your Java code in case the worst happens and your hard drive crashes. One tool that can output your code in virtually any format is Java Code Export which easily allows you to indent and export Java code into different file formats. You can even convert them to PDF so that you can print out, share and e-mail your code to others.