Can I start a thread again after it has died?

If I use start() on a Thread object and the run() method returns, is it possible to call start() again?

eg,

MyThread myThread = new MyThread();
myThread.start();
// run method executes and returns in 2 seconds
// sleep for 5 seconds to make sure the thread has died
myThread.start();

I'm just wondering because my code is throwing IllegalThreadStateExceptions, so want to know if it's because you can't do t开发者_如何学运维he above.

No, you can't. And the Javadoc for the Thread.start() method tells you that!

From a comment:

Is there anything else I could do to re-start a thread?

You could use ThreadPoolExecutor, which would allow you to pass in tasks and let the service assign a thread to a task. When the task is finished, the thread goes idle until it gets the next task.

So, you don't restart a thread, but you would redo/resume a task.

Nope.

From the Javadoc for java.lang.Thread:

It is never legal to start a thread more than once.

From the javadoc:

It is never legal to start a thread more than once. In particular, a thread may not be restarted once it has completed execution.

See the Thread.start() javadoc for more information.

There are other ways to accomplish what you are trying to do. For example, you could use new Threads that continue the work that was done in the Thread that has finished execution. You may also want to investigate the java.util.concurrent package.

Perhaps there is a better way of doing this if you want the thread to stop and restart multiple times. I have a tile caching thread in C++ that does something similar; it pauses when it's finished, and unpaused when it's needed again. I am new to Java, but from what I can tell, you can use Object.wait() to pause, and Object.notify() to resume threads. Maybe you could check those out in the documentation and redesign your thread to pause and resume instead of exiting.