How to decompile a Java .class file from rt.jar

Question

I have extracted a .class file from the rt.jar file in jre1.7, and have attempted to open it using notepad++, however it is unreadable. How can I decompile the .class file into a .java file so I can view the code?

Please note that I am interested in the decompilation of the code, not viewing the source code provided in the JDK downloads.

Answer 1

As @Jon Skeet said, don't use JRE but JDK, which contains the entire source code. If you for some reason insist on your approach, then I recommend JD-GUI for decompilation.

Answer 2

.class files are the compiled binary files. You can't read the Java code from them, but you can run them. If you want to see the source you usually need .java files. These are either packed in the same jar but then the src folder, or they can be downloaded in a seperate package.

Answer 3

You can use any decompiler tool like cavaj for decompiling a class file to source code (java file). I'm using it, and it works perfectly.

Answer 4

Try any of the decompilers listed here:

• Procyon - https://bitbucket.org/mstrobel/procyon/wiki/Java%20Decompiler
• CFR - http://www.benf.org/other/cfr/
• JD - http://jd.benow.ca/
• Fernflower - https://github.com/fesh0r/fernflower

Or use online decompiler - http://www.javadecompilers.com/