Is there a way to include whole Java source code into an eclipse project so the program is easier to debbug (e.g. by inserting println in methods you otherwise couldn't insert anything)?
I have a bug in my code. But to better understand why the bug in my code appears, I'd like to see what intermediate results in some system method (on which use the bug occurs) are.
For example, I'd like to know what JViewPort.scrollRectToVisible() exactly does and how my input behaves in it by printing out some intermediate results that occur in the method itself.
EDIT:
Instead of using JRE System Library X, I want to add the source code from JDK as if I had written the code myself. I want to be able to edit any System class just as I am able to edit any class I created myself. I want editable .java files, not packed .jars...
You cannot change the library code, but you can view it by using de-compiler. The max you can do is this. Now if you change any code in the libraries which you reached via the de-compiler, you would find an error stating "the integrity of the .jar package has changed which is not allowed"