ObjectPool defines a simple pooling interface.

• GenericObjectPool: ObjectPool implementation with a FIFO (First In First Out) behavior. This queue like behavior makes sure each object is regularly used. (helps preventing time-outs)
• StackObjectPool: ObjectPool implementation with a LIFO (Last In First Out) behavior.
• SoftReferenceObjectPool: ObjectPool implementation with a LIFO (Last In First Out) behavior. Additionally this pool wraps each object in a SoftReference allowing the garbage collector to remove them in response to memory demand.

A KeyedObjectPool pools instances of multiple types. Each type may be accessed using an arbitrary key.

• GenericKeyedObjectPool: ObjectPool implementation with a FIFO (First In First Out) behavior.
• StackKeyedObjectPool: ObjectPool implementation with a LIFO (Last In First Out) behavior.