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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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*/ |
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|
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package java.util.concurrent; |
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|
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/** |
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* A <tt>Future</tt> represents the result of an asynchronous |
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* computation. Methods are provided to check if the computation is |
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* complete, to wait for its completion, and to retrieve the result of |
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* the computation. The result can only be retrieved using method |
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* <tt>get</tt> when the computation has completed, blocking if |
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* necessary until it is ready. Once the computation has completed, |
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* the computation cannot be restarted or cancelled. |
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* |
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* <p> |
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* <b>Sample Usage</b> (Note that the following classes are all |
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* made-up.) <p> |
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* <pre> |
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* interface ArchiveSearcher { String search(String target); } |
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* class App { |
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* Executor executor = ... |
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* ArchiveSearcher searcher = ... |
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* void showSearch(final String target) throws InterruptedException { |
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* Future<String> future = |
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* new FutureTask<String>(new Callable<String>() { |
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* public String call() { |
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* return searcher.search(target); |
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* }}); |
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* executor.execute(future); |
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* displayOtherThings(); // do other things while searching |
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* try { |
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* displayText(future.get()); // use future |
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* } catch (ExecutionException ex) { cleanup(); return; } |
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* } |
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* } |
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* </pre> |
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* |
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* The {@link Executors} class contains more convenient methods |
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* for common usages. For example, the above explicit |
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* construction could be replaced with: |
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* <pre> |
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* Future<String> future = Executors.execute(executor, |
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* new Callable<String>() { |
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* public String call() { |
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* return searcher.search(target); |
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* }}); |
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* </pre> |
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* @see FutureTask |
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* @see Executor |
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* @since 1.5 |
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* @author Doug Lea |
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*/ |
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public interface Future<V> extends Cancellable { |
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|
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/** |
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* Waits if necessary for computation to complete, and then |
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* retrieves its result. |
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* |
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* @return computed result |
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* @throws CancellationException if this future was cancelled. |
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* @throws ExecutionException if underlying computation threw an |
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* exception |
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* @throws InterruptedException if current thread was interrupted |
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* while waiting |
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*/ |
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V get() throws InterruptedException, ExecutionException; |
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|
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/** |
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* Waits if necessary for at most the given time for the computation |
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* to complete, and then retrieves its result. |
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* |
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* @param timeout the maximum time to wait |
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* @param granularity the time unit of the timeout argument |
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* @return computed result |
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* @throws ExecutionException if underlying computation threw an |
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* exception |
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* @throws InterruptedException if current thread was interrupted |
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* while waiting |
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* @throws TimeoutException if the wait timed out |
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*/ |
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V get(long timeout, TimeUnit granularity) |
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throws InterruptedException, ExecutionException, TimeoutException; |
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} |
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