Possible Duplicate:
How to decompile a whole Jar file?
I want to see the classes, the code and how it is designed. When I try to open a .class in Netbeans, it says that they cannot be open. Am I missing something? How to see the code behind a .jar file?
You must find a java decompiler to see the code. If it has been obfuscated, you won't get anything helpful.
Most jar files won't have source inside them. If the jar files are for open source software, you should be able to find the source on the same website where you got the jar files.
If you can't find the source, you can try decompiling the compiled class files (described in another answer). You may not legally have the right to do this, however.
