BlockingDeque<E> A Deque that additionally supports blocking operations that wait for the deque to become non-empty when retrieving an element, and wait for space to become available in the deque when storing an element. 
BlockingQueue<E> A Queue that additionally supports operations that wait for the queue to become non-empty when retrieving an element, and wait for space to become available in the queue when storing an element. 
Callable<V> A task that returns a result and may throw an exception. 
CompletionService<V> A service that decouples the production of new asynchronous tasks from the consumption of the results of completed tasks. 
ConcurrentMap<K, V> A Map providing thread safety and atomicity guarantees. 
ConcurrentNavigableMap<K, V> A ConcurrentMap supporting NavigableMap operations, and recursively so for its navigable sub-maps. 
Delayed A mix-in style interface for marking objects that should be acted upon after a given delay. 
Executor An object that executes submitted Runnable tasks. 
ExecutorService An Executor that provides methods to manage termination and methods that can produce a Future for tracking progress of one or more asynchronous tasks. 
ForkJoinPool.ForkJoinWorkerThreadFactory Factory for creating new ForkJoinWorkerThreads. 
ForkJoinPool.ManagedBlocker Interface for extending managed parallelism for tasks running in ForkJoinPools. 
Future<V> A Future represents the result of an asynchronous computation. 
RejectedExecutionHandler A handler for tasks that cannot be executed by a ThreadPoolExecutor
RunnableFuture<V> A Future that is Runnable
RunnableScheduledFuture<V> A ScheduledFuture that is Runnable
ScheduledExecutorService An ExecutorService that can schedule commands to run after a given delay, or to execute periodically. 
ScheduledFuture<V> A delayed result-bearing action that can be cancelled. 
ThreadFactory An object that creates new threads on demand. 
TransferQueue<E> A BlockingQueue in which producers may wait for consumers to receive elements. 


AbstractExecutorService Provides default implementations of ExecutorService execution methods. 
ArrayBlockingQueue<E> A bounded {@linkplain BlockingQueue blocking queue} backed by an array. 
ConcurrentHashMap<K, V> A hash table supporting full concurrency of retrievals and high expected concurrency for updates. 
ConcurrentHashMap.KeySetView<K, V> A view of a ConcurrentHashMap as a Set of keys, in which additions may optionally be enabled by mapping to a common value. 
ConcurrentLinkedDeque<E> An unbounded concurrent {@linkplain Deque deque} based on linked nodes. 
ConcurrentLinkedQueue<E> An unbounded thread-safe {@linkplain Queue queue} based on linked nodes. 
ConcurrentSkipListMap<K, V> A scalable concurrent ConcurrentNavigableMap implementation. 
ConcurrentSkipListSet<E> A scalable concurrent NavigableSet implementation based on a ConcurrentSkipListMap
CopyOnWriteArrayList<E> A thread-safe random-access list. 
CopyOnWriteArraySet<E> A Set that uses an internal CopyOnWriteArrayList for all of its operations. 
CountDownLatch A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes. 
CountedCompleter<T> A ForkJoinTask with a completion action performed when triggered and there are no remaining pending actions. 
CyclicBarrier A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point. 
DelayQueue<E extends Delayed> An unbounded {@linkplain BlockingQueue blocking queue} of Delayed elements, in which an element can only be taken when its delay has expired. 
Exchanger<V> A synchronization point at which threads can pair and swap elements within pairs. 
ExecutorCompletionService<V> A CompletionService that uses a supplied Executor to execute tasks. 
Executors Factory and utility methods for Executor, ExecutorService, ScheduledExecutorService, ThreadFactory, and Callable classes defined in this package. 
ForkJoinPool An ExecutorService for running ForkJoinTasks. 
ForkJoinTask<V> Abstract base class for tasks that run within a ForkJoinPool
ForkJoinWorkerThread A thread managed by a ForkJoinPool, which executes ForkJoinTasks. 
FutureTask<V> A cancellable asynchronous computation. 
LinkedBlockingDeque<E> An optionally-bounded {@linkplain BlockingDeque blocking deque} based on linked nodes. 
LinkedBlockingQueue<E> An optionally-bounded {@linkplain BlockingQueue blocking queue} based on linked nodes. 
LinkedTransferQueue<E> An unbounded TransferQueue based on linked nodes. 
Phaser A reusable synchronization barrier, similar in functionality to CyclicBarrier and CountDownLatch but supporting more flexible usage. 
PriorityBlockingQueue<E> An unbounded {@linkplain BlockingQueue blocking queue} that uses the same ordering rules as class PriorityQueue and supplies blocking retrieval operations. 
RecursiveAction A recursive resultless ForkJoinTask
RecursiveTask<V> A recursive result-bearing ForkJoinTask
ScheduledThreadPoolExecutor A ThreadPoolExecutor that can additionally schedule commands to run after a given delay, or to execute periodically. 
Semaphore A counting semaphore. 
SynchronousQueue<E> A {@linkplain BlockingQueue blocking queue} in which each insert operation must wait for a corresponding remove operation by another thread, and vice versa. 
ThreadLocalRandom A random number generator isolated to the current thread. 
ThreadPoolExecutor An ExecutorService that executes each submitted task using one of possibly several pooled threads, normally configured using Executors factory methods. 
ThreadPoolExecutor.AbortPolicy A handler for rejected tasks that throws a RejectedExecutionException
ThreadPoolExecutor.CallerRunsPolicy A handler for rejected tasks that runs the rejected task directly in the calling thread of the execute method, unless the executor has been shut down, in which case the task is discarded. 
ThreadPoolExecutor.DiscardOldestPolicy A handler for rejected tasks that discards the oldest unhandled request and then retries execute, unless the executor is shut down, in which case the task is discarded. 
ThreadPoolExecutor.DiscardPolicy A handler for rejected tasks that silently discards the rejected task. 


TimeUnit A TimeUnit represents time durations at a given unit of granularity and provides utility methods to convert across units, and to perform timing and delay operations in these units. 


BrokenBarrierException Exception thrown when a thread tries to wait upon a barrier that is in a broken state, or which enters the broken state while the thread is waiting. 
CancellationException Exception indicating that the result of a value-producing task, such as a FutureTask, cannot be retrieved because the task was cancelled. 
ExecutionException Exception thrown when attempting to retrieve the result of a task that aborted by throwing an exception. 
RejectedExecutionException Exception thrown by an Executor when a task cannot be accepted for execution. 
TimeoutException Exception thrown when a blocking operation times out.