Java ThreadPoolExecutor getCompletedTaskCount() Method

The getCompletedTaskCount() of ThreadPoolExecutor is used to calculate the total number of tasks that have been completed. We can only approximate the number of tasks because the states of threads and tasks may change dynamically. The number of tasks returned by this method does not ever decrease across successive calls.

Syntax

Parameters

Return

The number of tasks

Throw

Example 1

import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.lang.Thread;
public class ThreadPoolExecutorgetCompletedTaskCountExample1  {
	public static void main(final String[] arguments) throws InterruptedException {
            ThreadPoolExecutor executor = (ThreadPoolExecutor)Executors.newCachedThreadPool();
            executor.submit(new Task());
            executor.submit(new Task());
            System.out.println("Completed task count : "+ executor.getCompletedTaskCount());
            executor.shutdown();
          }  
      static class Task implements Runnable {
     @Override
      public void run() {
         try {
             Long duration = (long) (Math.random() * 5);
             System.out.println("Running Thread Name: " + Thread.currentThread().getName());
             TimeUnit.SECONDS.sleep(duration);
             System.out.println("Completed Thread Name: " +Thread.currentThread().getName());
          } catch (InterruptedException e) {  }
      }
   }
}

Test it Now

Output:

Completed task count : 0
Running Thread Name: pool-1-thread-1
Running Thread Name: pool-1-thread-2
Completed Thread Name: pool-1-thread-1
Completed Thread Name: pool-1-thread-2

Example 2

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.lang.Thread;
import java.util.logging.Level;
import java.util.logging.Logger;
public class ThreadPoolExecutorgetCompletedTaskCountExample2  {
  public static void main(String[] args) {
                       Task5 task1 = new Task5("t1");
                       System.out.println("Starting threads");
                       ThreadPoolExecutor tExecutor = (ThreadPoolExecutor) Executors.newCachedThreadPool();
                       System.out.println(" Before execute Currently executing threads: "+ tExecutor.getActiveCount());
                       tExecutor.execute(task1); // start task1
                       System.out.println(" After execute Currently executing threads: "+ tExecutor.getActiveCount());
                       tExecutor.shutdown(); // shutdown worker threads
                       System.out.println("Threads started, main ends\n");
                              }
                                                  }
 class Task5 implements Runnable {
                   private final String threadName;
                   public Task5(String threadName) {
                               this.threadName = threadName;
                            }
                      @Override
                        public void run() {
                                for(int i=0 ; i<=10;i++)
                                     {
                                       if(i<5)
                                             {
                                        try {
                                              System.out.println("Thread sleeping for 1000 i=" +i);
                                              Thread.sleep(1000);
                                             } catch (InterruptedException ex) {
                                 Logger.getLogger(Task5.class.getName()).log(Level.SEVERE, null, ex);
                                         }
                                               }
                                           else{
                                                 System.out.println(" now  i > 5 :");
                                                  break;
                                              }
                                        }
                              }
}

Test it Now

Output:

Starting threads
Threads started, main ends
Thread sleeping for 1000 i=0
Thread sleeping for 1000 i=1
Thread sleeping for 1000 i=2
Thread sleeping for 1000 i=3
Thread sleeping for 1000 i=4
xf now  i > 5 :

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