Stopping a Thread

[Sharada Kumaran]

I need to stop a thread when I exit an application. I use myThread.stop(), but this is a deprecated method. Which is the correct way to terminate a thread?
The need arises because I am caling an application from another. On exiting the called application, when control returns to the first one, the thread is still running.
thanks,

[L Goundalkar]

Most uses of stop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. To ensure prompt communication of the stop-request, the variable must be volatile (or access to the variable must be synchronized).
For example, suppose your applet contains the following start, stop and run methods:
private Thread blinker;
public void start() {
blinker = new Thread(this);
blinker.start();
}
public void stop() {
blinker.stop(); // UNSAFE!
}
public void run() {
Thread thisThread = Thread.currentThread();
while (true) {
try {
thisThread.sleep(interval);
} catch (InterruptedException e){
}
repaint();
}
}
You can avoid the use of Thread.stop by replacing the applet's stop and run methods with:
private volatile Thread blinker;
public void stop() {
blinker = null;
}
public void run() {
Thread thisThread = Thread.currentThread();
while (blinker == thisThread) {
try {
thisThread.sleep(interval);
} catch (InterruptedException e){
}
repaint();
}
}
Thanks.


------------------
L Goundalkar
[e-mail]
Sun Certified Programmer for Java 2 Platform

[Sharada Kumaran]

Hey, thats a clean solution. I got the idea, but don't you think that I don't need to override Thread.stop
Is there a problem with this -
public void windowClosing(WindowEvent e){
blinker = null;
System.exit(0);
}
public void run{
while (blinker == myThread)
{
repaint();
}
I ask this because something else I read about setting the reference to null, had me confused.
thanks for your neat solution anyway!

[Anonymous]

The reason that Thread.stop is deprecated is that it can corrupt memory. That's why everyone says to stay away from it.
Stick with code that has a thread check itself to see if it needs to stop executing. That will be your safest bet.
Regards

------------------
Brian Hoff
Sun Certified Programmer for the Java� 2 Platform