对于线程池execute以及submit你都了解吗?那么execute和submit这两者之间的区别是什么呢?很多人表示不大清楚，下面一起来了解一下。
代码：
public class ThreadPool_Test
{
public static void main(String[] args) throws InterruptedException, ExecutionException
{
ExecutorService pool = Executors.newCachedThreadPool();
pool.execute(new MyRunner());
Future < String > future = pool.submit(new MyCaller());
String ret = future.get();
System.out.println(ret);
}
}
class MyCaller implements Callable < String >
{
@Override
public String call() throws Exception
{
System.out.println("calling");
return "return_from_call";
}
}
class MyRunner implements Runnable
{
@Override
public void run()
{
System.out.println("running");
}
}execute方法执行runnable 任务，submit方法执行callable任务，callable任务有返回值，但是，runnable不一样，runnable任务是void的，没有返回值。
// void java.util.concurrent.ThreadPoolExecutor
final void runWorker(Worker w)
{
Thread wt = Thread.currentThread();
Runnable task = w.firstTask;
w.firstTask = null;
w.unlock(); // allow interrupts
boolean completedAbruptly = true;
try
{
while (task != null || (task = getTask()) != null)
{
w.lock();
if ((runStateAtLeast(ctl.get(), STOP) ||
(Thread.interrupted() &&
runStateAtLeast(ctl.get(), STOP))) &&
!wt.isInterrupted())
wt.interrupt();
try
{
beforeExecute(wt, task);
Throwable thrown = null;
try
{
task.run();
}
catch (RuntimeException x)
{
thrown = x;
throw x;
}
catch (Error x)
{
thrown = x;
throw x;
}
catch (Throwable x)
{
thrown = x;
throw new Error(x);
}
finally
{
afterExecute(task, thrown);
}
}
finally
{
task = null;
w.completedTasks++;
w.unlock();
}
}
completedAbruptly = false;
}
finally
{
processWorkerExit(w, completedAbruptly);
}
}Runnable，task是MyRunner。
Callable，task是FutureTask。
submit方法的调用栈：
创建FutureTask对象，将Callable对象包裹起来，在run方法中调用Callable对象的方法，并且，设置返回值。
// java.util.concurrent.FutureTask.FutureTask
public FutureTask(Callable < V > callable)
{
if (callable == null)
throw new NullPointerException();
this.callable = callable;
this.state = NEW; // ensure visibility of callable
}
public void run()
{
if (state != NEW ||
!UNSAFE.compareAndSwapObject(this, runnerOffset
, null, Thread.currentThread()))
return;
try
{
Callable < V > c = callable;
if (c != null && state == NEW)
{
V result;
boolean ran;
try
{
result = c.call();
ran = true;
}
catch (Throwable ex)
{
result = null;
ran = false;
setException(ex);
}
if (ran)
set(result);
}
}
finally
{
// runner must be non-null until state is settled to
// prevent concurrent calls to run()
runner = null;
// state must be re-read after nulling runner to prevent
// leaked interrupts
int s = state;
if (s >= INTERRUPTING)
handlePossibleCancellationInterrupt(s);
}
}线程池execute以及submit的区别你都了解了吗?在java入门学习当中，线程池方面的问题是经常会碰到的，希望上面的文章可以对你有所帮助，更多java方面的常见问题，请继续通过本站来进行了解吧。
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