| Interface | Description | 
|---|---|
| Callable<V> | A task that returns a result and may throw an exception. | 
| Delayed | A mix-in style interface for marking objects that should be acted upon after a given delay. | 
| Executor | An object that executes submitted  Runnabletasks. | 
| ExecutorService | |
| Future<V> | A Future represents the result of an asynchronous computation. | 
| RunnableFuture<V> | |
| ScheduledExecutorService | An  ExecutorServicethat 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. | 
| Enum | Description | 
|---|---|
| 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. | 
| Exception | Description | 
|---|---|
| CancellationException | Exception indicating that the result of a value-producing task, 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  Executorwhen a task cannot be accepted for execution. | 
| TimeoutException | Exception thrown when a blocking operation times out. |