JavaExp: Java and Open Source Technology

The following section summarizes the various Collection Classes as of Java 7 and their important attributes Including HashMap which is not in Collection Framework. HashMap. It provides constant time operation for operations like get and put and remove. Iteration over the Collection values requires time proportional to the capacity of the Map.(values()). Default load factor is .75. HashMap does not maintain the order. HashMap is not synchronized. LinkedHashMap LinkedHashMap orders are maintained It provdes  constant-time performance for operations like get, put and remove. Performace is slightly slower then HashMap due to the overhead of maintaining Linked List. Re-insertion does not effect the insertion order. Iteration over the collection values is proportional to the size of the map    regardless capacity . TreeMap Red-Black tree based implementation. Implement the SortedMap Interface. Map is ascending Key order of the natural order. It has log(n) time cost for

The following section captures the main difference between wait and sleep method wait method wait sends the current thread to non-runnable  state thread releases the lock on the object before going to non-runnable state. wait ()  method is defined on Object class wait ()  is a instance method wait() should be called when the thread has already  acquired  the lock on the object the thread will be in non-runnable state untill the time is elapsed or another thread  invoked  notify() / notifyAll() method on the object sleep ()  method sleep ()  method will send the current thread to non-runnable state for the specified time. sleep() method is defined in Thread class sleep() method is a Static method. sleep ()  does not cause the thread to releases the lock on the object