Why I can't set a breakpoint in some of the Java source file (readonly source of plugin jar) in eclipse?

Question

I'm tracing into eclipse LTK plugin. I could set a breakpoint in some of the readonly java source for LTK. (for example ProcessorBasedRefactoring.java)

However, I couldn't set a breakpoint in some source files. (for example JavaRenameProcessor).

When I tried to set a method breakpoint, I got "Cannot create method breakpoint, method signature not available." error message.

What might be wrong? Why I can't set a breakpoint in some of the (binary) Java source file?

ADDED:

For a simple workaround to this issue, I just set a breakpoint wherever possible, and then open the java source to click a line. Then, I can use command-R so that eclipse executes up to the line that I point to.

ADDED2:

The breakpoint was there, but eclipse doesn't show it.

The other thing that I noticed was that the java file, just disappears from the IDE when I restart the debugger. And even when I reopen it in eclipse.

I got this error message - "zip file closed".

And then I can see the source code only when I trace into the method that the java source contains.

Answer 1

I believe that the class is compiled without debug information and/or the byte code is obfuscated.