Is it possible to debug classes in a third-party Android application?

I have an Android library that I distribute as a jar to third-parties who integrate it into t开发者_JS百科heir applications. A particular client is having a problem I wish to debug. Is it possible to rebuild their application into a form that I can debug?

Try decompiling. JavaDecompiler can do a good job with a jar. All files, in JAR files, are displayed.