Since i will be debugging/testing both the public or private methods i dont see how it would make a difference.
The difference is that you document some assumptions you made when you wrote the code for a method. For example if you decided that some (private) method should not be called with null as parameter value (under normal conditions) it's OK to have no null checks in this method because it simply expects that parameters should not be null when the method is used correctly. That's were asserts are a good way to document such assumptions inside the code itself.
But it's NOT ok to use asserts to validate input parameters for public methods because you simply cannot (always) contol what the caller of a method will give you as a parameter value.
You should make the necessary checks with the usual
Java tools but don't depend on asserts for your logic to work correctly. But it's fine to have asserts besides the regular check mechanism.
Marco