How to include third party classes without JAR file

I would like to use third party classes for which I have no source code. How do I inst开发者_StackOverflowantiate these classes (which are in an APK on the phone) if I have no source code. Is it possible to do in Java? If not, how can it be done?

What exactly are you trying to do? If you can root your phone I guess you could pull the APK off and try to analyze what the classes are doing using something like Apktool..

How do I instantiate these classes (which are in an APK on the phone) if I have no source code.

If the classes are in your project (as a JAR or source code), you use them normally, like any other class. If you do not know how to do that, contact whoever wrote the code and obtain documentation for them.

If the classes are not in your project, you cannot use them.