Cannot assign source to jar in eclipse

I'm using a java jar file in my eclipse project. Beside this, I have a "normal" folder including the sources of this jar. Now开发者_Go百科 I created a folder "lib" in my eclipse project, added the folder with the source files into it and attached this folder to the jar file. But everytime I want to open the code definition by clicking on a class (ctrl + click) I get the message "assign source code"... What is the mistake?

Does you JAR file only have .class files in it? If so you will need to Attach the Source i.e. .java files. I don't know if you have the .java source files in your possession.

If you do have the .java files (or they're in the JAR and aren't being picked up) you can use the "assign source.." dialog to point Eclipse to the location of the source files. If you don't have the source files, but want to see it then consider installing an Eclipse decompiler plugin e.g. JD-Eclipse