Executor (Java Platform SE 6)

This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.

Overview

Package

Class

PREV CLASS NEXT CLASS

FRAMES NO FRAMES

SUMMARY: NESTED | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

java.util.concurrent
interface Executor

All Known Subinterfaces:: ExecutorService, ScheduledExecutorService

public interface Executor

An object that executes submitted {@link Runnable} tasks. This interface provides a way of decoupling task submission from the mechanics of how each task will be run, including details of thread use, scheduling, etc. An Executor is normally used instead of explicitly creating threads. For example, rather than invoking new Thread(new(RunnableTask())).start() for each of a set of tasks, you might use:

 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 {@link ExecutorService}, which is a more extensive interface. The {@link ThreadPoolExecutor} class provides an extensible thread pool implementation. The {@link 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.

Method Summary
`void`	`execute(Runnable command)` Executes the given command at some time in the future.

Method Detail

execute

public void execute(Runnable command)

Executes the given command at some time in the future. The command may execute in a new thread, in a pooled thread, or in the calling thread, at the discretion of the Executor implementation.

Parameters:: command - the runnable task