Stopping and Starting Threads

[Michael Scott]

I have Java code that requires the 'sleep' method to be added in two places. Otherwise the code fails because of an unavailable resource. I'm interested in whether the code might be modified so that one thread stops before another starts. In other words, the process which is running when the code 'sleeps' does so on one thread, and the process which runs after the code 'sleeps' does so on another thread. This would seem to ensure that a resource is available when the second thread starts.

The two points in which sleep' is required are as follows.

1.) In this case, 'batCommand' is unavailable unless 'sleep' is added.

String batCommand = buffer.toString();
Runnable runnable = new BasicThread();
Thread thread = new Thread(runnable);
thread.sleep(8000);
Process batChild = Runtime.getRuntime().exec(batCommand);


2.) In this case, 'doc' is unavailable unless 'sleep' is added.

doc.save();
thread.sleep(8000);
RichTextItem body = doc.createRichTextItem("Test");


I'd appreciate any suggestions on how this code might be modified so that the threads stop and start as I've suggested.

Thanks.

[Stan James]

I'm guessing in 1 you accidentally left out the line that says "thread.start()"?? If you start another thread and wait for it to finish, you're not getting any benefit. But you can do it easily:

Thread thread = new Thread( runnable );
thread.start();
?              // would make more sense if we did something here
thread.join(); // waits until the other thread ends
Runtime.getRuntime...

Look up the doc on join() and see if that's what you need.

doc.save() may be a different problem. It looks like it starts another thread but doesn't give you access to it so you could join() it. If that's the case, see if doc has any kind of callback or event notification for when it's done.

[Ilja Preuss]

Take a look at whether the following things give you any ideas:

- the Producer/Consumer pattern
- the Java 5 Future class
- Object.wait and Object.notifyAll