Here's a demo of Polystyle's PHP obfuscator which works the same as the Java obfuscator:
With it you can obfuscate Java so that you can make your code hard to read. This allows you to sell your source code without anyone else being able to easily reverse engineer it.
Features include:
Strips comments, newlines where ever possible, jumbles variable and function names
Analyzes external code so that your function calls to existing libraries will still work
