How to view Java's byte code in eclipse IDE?

James Raitsev picture James Raitsev · Jun 17, 2010 · Viewed 35.6k times · Source

Sometimes, in Eclipse , i press a combination of keys which take me to the editor page that shows contents of my .class file (bytecode). I never seem to be able to remember what that key combination is.

Can someone please let me know?

Or in other words, how can one see own bytecode?

Answer

Mark Peters picture Mark Peters · Jun 17, 2010

Eclipse's default class file viewer shows the source (see VonC's answer) if it has been associated with the binaries, otherwise it gives a javap-like view of the class (with an option to attach source). I'm guessing it's the latter that you are looking for.

I've never found a way to cleanly force Eclipse to show that output rather than the linked source. What you probably want is an Eclipse plug-in that provides Javap like functionality (or an interface to javap). Look for plugins stating they "disassemble" (as opposed to "decompile," like jad).

Barring a plug-in, you could probably configure an external tool to perform javap but it might not play nicely with other eclipse features.

Edit: Let me be clear about the above: If you hit F3, Eclipse does the following (generally, the actual procedure might be slightly different):

  1. Resolves the target (if you are selecting a Java file, it will be the Java file itself; if you are selecting or your cursor is over a class name it will be the class declaration, similar for a method declaration, etc).
  2. Searches the build path (same project first) for a Java file containing the target. If found, opens up an writable editor displaying that Java source file.
  3. For class/method declarations, it continues searching references on your build path for a class file that contains the declaration. If it is found, then

    a) If the class file has had source attached to it, open up a read-only editor of the linked Java file.

    b) If the class file does not have source attached to it, then open up a read-only panel showing the disassembled (javap-like) bytecode of the compiled class file.

My guess would be that you're thinking there's a dedicated key sequence to 3.b), but I don't think there is. But again, I would love to be proven wrong here.