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Thread: Block thread until callback method has been called by other thread

  1. #1
    Junior Member
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    Default Block thread until callback method has been called by other thread

    Hi All,

    Please can you advise best way to block or suspend an application thread, until another thread has called a method in the application's class.

    Thank you for your time and help,
    Best regards,
    James

    public class ThreadTester {
      public static void main(String[] args) {
        new ThreadTester().application();
      }
     
      public void application() {
        for (int i=0; i<10; i++) {
          Thread t = new Thread(new Process(this, i));
          t.start();
          /* wait here until serviceSearchCompleted() has been called by Process */
        }
      }
     
      public void serviceSearchCompleted(int number) {
        System.out.println("Completed search " + number);
        /* notify application() method to continue beyond 'waiting point' */
      }
    }
     
     
     
    class Process implements Runnable {
      private ThreadTester threadTester;
      private int number;
     
      public Process(ThreadTester threadTester, int number) {
        this.threadTester = threadTester;
        this.number = number;
      }
     
      public void run() {
        startSearchServices();
      }
     
      private void startSearchServices() {
        System.out.println("Started search " + number);
        try {
          Thread.sleep(1000);  //...seaching...
        } catch (InterruptedException ie) {}
        threadTester.serviceSearchCompleted(number);
      }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Block thread until callback method has been called by other thread

    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Block thread until callback method has been called by other thread

    I have managed to RESOLVE this problem using the code below.

    public class ThreadTester {
      private Object synchObj = new Object();
     
      public static void main(String[] args) {
        new ThreadTester().application();
      }
     
      public void application() {
        for (int i=0; i<10; i++) {
          Thread t = new Thread(new Process(this, i));
          t.start();
          synchronized (synchObj) {
            try { synchObj.wait(); } catch (InterruptedException ie) {}
          }
        }
      }
     
      public void serviceSearchCompleted(int number) {
        System.out.println("Completed search " + number);
          synchronized (synchObj) {
            synchObj.notify();
          }
      }
    }
     
     
     
    class Process implements Runnable {
      private ThreadTester threadTester;
      private int number;
     
      public Process(ThreadTester threadTester, int number) {
        this.threadTester = threadTester;
        this.number = number;
      }
     
      public void run() {
        startSearchServices();
      }
     
      private void startSearchServices() {
        System.out.println("Started search " + number);
        try {
          Thread.sleep(1000);  //...seaching...
        } catch (InterruptedException ie) {}
        threadTester.serviceSearchCompleted(number);
      }
    }

  4. #4

  5. #5
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    Default Re: Block thread until callback method has been called by other thread

    You should utilize the concurrency package eg. with a Lock or a Barrier

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