edu.emory.mathcs.backport.java.util.concurrent
public interface Executor
Executor executor = anExecutor; executor.execute(new RunnableTask1()); executor.execute(new RunnableTask2()); ...However, the Executor interface does not strictly require that execution be asynchronous. In the simplest case, an executor can run the submitted task immediately in the caller's thread:
class DirectExecutor implements Executor { public void execute(Runnable r) { r.run(); } }More typically, tasks are executed in some thread other than the caller's thread. The executor below spawns a new thread for each task.
class ThreadPerTaskExecutor implements Executor { public void execute(Runnable r) { new Thread(r).start(); } }Many Executor implementations impose some sort of limitation on how and when tasks are scheduled. The executor below serializes the submission of tasks to a second executor, illustrating a composite executor.
class SerialExecutor implements Executor { final Queue<Runnable> tasks = new ArrayDeque<Runnable>(); final Executor executor; Runnable active; SerialExecutor(Executor executor) { this.executor = executor; } public synchronized void execute(final Runnable r) { tasks.offer(new Runnable() { public void run() { try { r.run(); } finally { scheduleNext(); } } }); if (active == null) { scheduleNext(); } } protected synchronized void scheduleNext() { if ((active = tasks.poll()) != null) { executor.execute(active); } } }The Executor implementations provided in this package implement ExecutorService, which is a more extensive interface. The ThreadPoolExecutor class provides an extensible thread pool implementation. The Executors class provides convenient factory methods for these Executors.
Memory consistency effects: Actions in a thread prior to submitting a {@code Runnable} object to an {@code Executor} happen-before its execution begins, perhaps in another thread.
Since: 1.5
Method Summary | |
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void | execute(Runnable command)
Executes the given command at some time in the future. |
Parameters: command the runnable task
Throws: RejectedExecutionException if this task cannot be accepted for execution. NullPointerException if command is null