Endless checking for null pointers
Is there anything to this complaint? Let me check if it's null before typing any more. Seems fine. Now let me check if my keyboard is still here and hasn't been replaced by something null. It's still here. Now I'll move my fingers and tell you why null testing is a pain.
Java requires endless if statements to test whether variables have ended up null; otherwise entire threads crash with NullPointerExceptions. Smartass developers say it's my fault for not checking the input at the beginning, but that's often not possible when creating libraries. If someone picks up this class file in the future, you better check all the variables yet again, because you have no idea how they will reuse it.