How to know when a thread ends.

Inside the run method of the Thread class have a boolean method take value true when it finishes. That variable will be declared as an attribute of the class.

When you call the thread have a while loop checking that variable when it becomes true you will exit the loop

Thanks for the info.

So, lets consider the following code. Please correct me if I am wrong.

public class MainClass {
   int final MAX = 10;
   int counter = MAX;
   public static void main (String[] arg) {
      for (int i=0; i < MAX; i++) {
         ThreadClass tc = new ThreadClass();
         tc.start();
      }
   }

   public static synchronized void updateCounter() {
      counter--;
   }
   public int getCounter () {
      return counter;
   }
}

//----------------------------
public class ThreadClass extends Thread {
   public void run () {
      while (some condition is true) {
         doSomeOperationHere();
      }
      MainClass.updateCounter();
   }
}

//-------------------------------
public class ProgressThread extends Thread {
   public void run () {
      while (MainClass.getCounter() > 0) {
         // calculate and display progress bar
      }
   }
}

Will this work?

Thanks.

Here's one way you could monitor progress on the tasks. It involves timed polling of the progress of each task.

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import javax.swing.ProgressMonitor;

public class ProgressDemo {

    public static void main(String[] args) {
        WorkQueue work = new WorkQueue();
        work.begin();
    }

    static class WorkQueue {

        final int NUM_THREADS = 5;
        ExecutorService execService = 
          Executors.newFixedThreadPool(NUM_THREADS);
        
        int totalThingsToDo = 0;
        int percentComplete = 0;

        public void begin() {
            totalThingsToDo = 100;
            List<LongTask> tasks = new ArrayList<LongTask>();
            
            // create and submit tasks to thread pool
            for (int i = 0; i < NUM_THREADS; i++) {
                LongTask task = 
                  new LongTask(totalThingsToDo/NUM_THREADS, i);
                tasks.add(task);
                execService.submit(task);
            }
            
            ProgressMonitor monitor = new ProgressMonitor(null, 
              "Doing stuff...", "", 0, 100);
            
            // monitor progress until done
            while (percentComplete < 100) {
                int partialProgress = 0;
                for (LongTask task : tasks) {
                    partialProgress += task.getProgress();
                }
                percentComplete = 
                  (int)(partialProgress / (float)tasks.size());
                
                try {
                    // wait one second between progress updates
                    Thread.sleep(1000);
                } catch (InterruptedException ie) {
                    Thread.currentThread().interrupt();
                }
                
                monitor.setNote(percentComplete+" %");
                monitor.setProgress(percentComplete);
            }
            // shutdown the thread pool
            execService.shutdown();
        }
    }

    /** Mock task that does an arbitrarty number
     * of "things" in a random amount of time.
     */
    static class LongTask implements Callable<Boolean> {

        int thingsToDo = 0;
        int thingsDone = 0;
        int taskId=0;

        public LongTask(int thingsToDo, int taskId) {
            this.thingsToDo = thingsToDo;
            this.taskId = taskId;
        }

        public Boolean call() throws Exception {
            boolean completed = false;
            while (thingsDone < thingsToDo) {
                // random pause to simulate "working" 
                Thread.sleep((int)(Math.random() * 3000));
                thingsDone++;
            }
            System.out.println(taskId + " done");
            return Boolean.valueOf(completed);
        }

        public int getProgress() {
            return (int)(thingsDone / (float)thingsToDo * 100f);
        }
    }
}

Alternately, you could provide a reference to the WorkQueue class to the tasks and a call-back method that each task could use to publish it's progress (basically making the WorkQueue a listener for progress updates generated by the tasks). An example of that implementation can be seen here in the Swing progress bar tutorial: http://java.sun.com/docs/books/tutorial/uiswing/components/progress.html

Thanks Ezzaral. I used a counter to determine whether each thread is finished. And it's working now.

Glad to hear it. I posted that example around the same time that you posted what you were trying, so there was a little overlap. It also went a little bit further than your stated goal of just using thread completion to increment progress, but the intent was to show a progress polling mechanism. Your own code basically uses the alternative mechanism I mentioned at the bottom of the post, with each thread calling back to a central method to report progress. Collectively those two mechanisms represent a push versus pull paradigm in the communication process.

hai new_2_java can you please send me a java program to play list of audio files using JMF

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