Java ThreadPoolExecutor purge() Method

The purge() method of ThreadPoolExecutor class tries to remove from the work queue all Future tasks that have been canceled.

Syntax

Parameters

Returns

Does not return value.

Throw

Does not throw an exception.

Example 1

import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.lang.Thread;
public class ThreadPoolExecutorpurgeExample1    {
            public static void main(final String[] arguments) throws InterruptedException {
                     ThreadPoolExecutor executor = (ThreadPoolExecutor)Executors.newCachedThreadPool();
                     executor.submit(new Task());
                     executor.submit(new Task());
                     executor.shutdown();
                     executor.purge();
               }  
      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:

Running Thread Name: pool-1-thread-2
Running Thread Name: pool-1-thread-1
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 ThreadPoolExecutorpurgeExample2  {
     public static void main(String[] args) {
                 WorkDD task1 = new WorkDD("t1");    
                 System.out.println("Starting threads");
                 ThreadPoolExecutor tExecutor = (ThreadPoolExecutor) Executors.newCachedThreadPool();
                 tExecutor.submit(task1); 
                 tExecutor.execute(task1); // start task1
                 tExecutor.shutdown(); // shutdown worker threads
                 tExecutor.purge();  
         }
}

 class WorkDD implements Runnable {
  private final String threadName;
 public WorkDD(String threadName) {
    this.threadName = threadName;
   }
  
  @Override
  public void run() {
      for(int i=4 ; i<=9;i++)
      {
          if(i==5)
          {
              System.out.println("i=" +i);
              }
          }
          
      }
}

Test it Now

Output: