Java Application Common Problems

My Java application was running fine some time before and now in the later release, it is slow or it is acting unresponsive. At times, it hangs too.
Well, some of the problems with java application could be following:

1. Insufficient memory. The symptom is when one gets OutOfMemoryError.
2. Memory Leaks: Following could be symptoms:
    - Growing use of memory
    - A class with high growth rate
    - A class with an unexpected number of instances
    - An object being referenced unintentionally
3. Finalizers: Objects are pending for finalization
4. Deadlocks: Thread blocks on object monitor or java.util.concurrent locks
5. Looping threads: Threads CPU time is continuously increasing
6. High lock contention: Thread with high contention statistics