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Greenhorn
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hello there
can anybody tell me exactly "setdaemon(true)" means in thread
i got this from dan'sclass A extends Thread {
public void run() {
synchronized (this) {
try {wait();} catch (InterruptedException ie){}
}}
public static void main(String[] args) {
A a1 = new A();
a1.setDaemon(true);
long startTime = System.currentTimeMillis();
a1.start();
System.out.print(System.currentTimeMillis() - startTime + ",");
i'd appreciated
 
Ranch Hand
Posts: 3271
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Marking a thread as a "daemon" thread means that the JVM no longer waits for it to complete before exiting. Your Java application terminates when there are no longer and "non-daemon" threads executing. When the last non-dameon thread completes, the application exits. If there is one or more "daemon" threads running when that occurs, those threads automatically quit.
Daemon threads are great for "support" tasks that constantly run. Garbage collection is a perfect example. It's something that runs continuously (or periodically) but, when all of the other processing is completed, there's no reason for garbage collection to continue. That's a perfect use for a daemon thread.
I hope that helps,
Corey
 
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It's also important to note that even when the main thread is done , if you still have non-daemon threads running , the app will still continue to run until those non-daemon threads are done.If , however , the main thread is done , and the non-daemon threads are also done , all remaining daemon threads are terminated by the JVM.
jeff mutonho
 
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