+ * Sample Usage (Note that the following classes are all + * made-up.)
+ *
{@code
+ * interface ArchiveSearcher { String search(String target); }
+ * class App {
+ * ExecutorService executor = ...
+ * ArchiveSearcher searcher = ...
+ * void showSearch(final String target)
+ * throws InterruptedException {
+ * Future future
+ * = executor.submit(new Callable() {
+ * public String call() {
+ * return searcher.search(target);
+ * }});
+ * displayOtherThings(); // do other things while searching
+ * try {
+ * displayText(future.get()); // use future
+ * } catch (ExecutionException ex) { cleanup(); return; }
+ * }
+ * }}
+ *
+ * The {@link FutureTask} class is an implementation of Future that
+ * implements Runnable, and so may be executed by an Executor.
+ * For example, the above construction with submit could be replaced by:
+ * {@code
+ * FutureTask future =
+ * new FutureTask(new Callable() {
+ * public String call() {
+ * return searcher.search(target);
+ * }});
+ * executor.execute(future);}
+ *
+ * Memory consistency effects: Actions taken by the asynchronous computation
+ * happen-before
+ * actions following the corresponding {@code Future.get()} in another thread.
+ *
+ * @see FutureTask
+ * @see Executor
+ * @since 1.5
+ * @author Doug Lea
+ * @param After this method returns, subsequent calls to {@link #isDone} will
+ * always return true. Subsequent calls to {@link #isCancelled}
+ * will always return true if this method returned true.
+ *
+ * @param mayInterruptIfRunning true if the thread executing this
+ * task should be interrupted; otherwise, in-progress tasks are allowed
+ * to complete
+ * @return false if the task could not be cancelled,
+ * typically because it has already completed normally;
+ * true otherwise
+ */
+ boolean cancel(boolean mayInterruptIfRunning);
+
+ /**
+ * Returns true if this task was cancelled before it completed
+ * normally.
+ *
+ * @return true if this task was cancelled before it completed
+ */
+ boolean isCancelled();
+
+ /**
+ * Returns true if this task completed.
+ *
+ * Completion may be due to normal termination, an exception, or
+ * cancellation -- in all of these cases, this method will return
+ * true.
+ *
+ * @return true if this task completed
+ */
+ boolean isDone();
+
+ /**
+ * Waits if necessary for the computation to complete, and then
+ * retrieves its result.
+ *
+ * @return the computed result
+ * @throws CancellationException if the computation was cancelled
+ * @throws ExecutionException if the computation threw an
+ * exception
+ * @throws InterruptedException if the current thread was interrupted
+ * while waiting
+ */
+ V get() throws InterruptedException, ExecutionException;
+
+ /**
+ * Waits if necessary for at most the given time for the computation
+ * to complete, and then retrieves its result, if available.
+ *
+ * @param timeout the maximum time to wait
+ * @param unit the time unit of the timeout argument
+ * @return the computed result
+ * @throws CancellationException if the computation was cancelled
+ * @throws ExecutionException if the computation threw an
+ * exception
+ * @throws InterruptedException if the current thread was interrupted
+ * while waiting
+ * @throws TimeoutException if the wait timed out
+ */
+ V get(long timeout, TimeUnit unit)
+ throws InterruptedException, ExecutionException, TimeoutException;
+}