Java ThreadPoolExecutor afterExecute() Method

The afterExecute() method of ThreadPoolExecutor class is invoked after execution of the given Runnable. This method is invoked by the same thread that executed the task.

Syntax

Parameters

r - the runnable that has completed

t - the exception that caused termination, or null if execution completed normally

Return value

Throw

RuntimeException.

Example 1

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class ThreadPoolExecutorafterExecuteExample1  {
	public static void main(String[] args) {
		                      //Creating a thread pool
		                            ThreadPoolExecutor obj = new ThreadPoolExecutorafterExecuteExample1().new MyThreadExecutor(2, 3, 1,
				            TimeUnit.SECONDS, new LinkedBlockingQueue<>());
  		                       //execute a runnable
		                             obj.execute(() -> {
                                                                System.out.println("In Runnable!");
                                                            });
		                             obj.shutdown();
	                              }
class MyThreadExecutor extends ThreadPoolExecutor {
		              public MyThreadExecutor(int PoolSize, int maxPoolSize, long keepAliveTime, TimeUnit unit,
				  BlockingQueue<Runnable> workQueue) {
			                                         super(PoolSize, maxPoolSize, keepAliveTime, unit, workQueue);
		                                              }

		@Override
		protected void afterExecute(Runnable run, Throwable throw1) {
			            super.afterExecute(run, throw1);
			            if (throw1 == null)
				          System.out.println("Completed!! without any Exception");
			            else
				           System.out.println("encountered exception- " +throw1.getMessage());
		                                             }
	}
}

Test it Now

Output:

In Runnable!
Completed!! without any Exception

Example 2

package ThreadPoolExecutorClass;
import java.util.concurrent.*;
 class MYThreadPoolExecutor extends ThreadPoolExecutor {
  public MYThreadPoolExecutor() { 
       super(1,10,60,TimeUnit.SECONDS,new ArrayBlockingQueue<Runnable>(1000));
   }
   @Override
   protected void afterExecute(Runnable r, Throwable t) {
     super.afterExecute(r, t);
     if (t == null && r instanceof Future<?>) {
       try {
         Object Obj = ((Future<?>) r).get();
         System.out.println(Obj);
       } catch (InterruptedException | ExecutionException e) {  } 
     }
       }
 }
public class ThreadPOolExecutorafterExecuteExample2 {
    public static void main(String args[]){
        System.out.println("creating service");
        //ExecutorService service = Executors.newFixedThreadPool(10);
        MYThreadPoolExecutor obj2 = new MYThreadPoolExecutor();
        Future<?> sb = obj2.submit(() -> {
            int a=4, b = 0;
            System.out.println("a and b="+a+":"+b);
            System.out.println("a/b:"+(a/b));
            System.out.println("Thread Name in Runnable after divide by zero:"+Thread.currentThread().getName());
        });
        obj2.shutdown();
    }
}

Test it Now

Output: