Java ThreadPoolExecutor getRejectedExecutionHandler() Method

The getRejectedExecutionHandler() method of ThreadPoolExecutor class returns the current handler for un-executable tasks.

Syntax

Parameters

No parameter is passed.

Return

The current handler

Throw

Does not throw the exception.

Example 1

import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.lang.Thread;
    public class ThreadPoolExecutorgetRejectedExecutionHandlerExample1  {
                       public static void main(final String[] arguments) throws InterruptedException {
                       ThreadPoolExecutor executor = (ThreadPoolExecutor)Executors.newCachedThreadPool();
                       executor.submit(new Task());
                       System.out.println("POOL SIZE : "+ executor.getPoolSize());
                       executor.submit(new Task());
                       executor.shutdown();
                       System.out.println("get rejected exception handler :"+ executor.getRejectedExecutionHandler());
                      }  
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:

POOL SIZE : 1
get rejected exception handler :java.util.concurrent.ThreadPoolExecutor$AbortPolicy@33909752
Running Thread Name: pool-1-thread-2
Running Thread Name: pool-1-thread-1
Completed Thread Name: pool-1-thread-2
Completed Thread Name: pool-1-thread-1

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 ThreadPoolExecutorgetRejectedExecutionHandlerExample2  {
           public static void main(String[] args) {
                      Work23 task1 = new Work23("t1");
                      Work23 task2 = new Work23("t2");
                      System.out.println("Starting threads");
                 ThreadPoolExecutor tExecutor = (ThreadPoolExecutor) Executors.newCachedThreadPool();
                 System.out.println("  Maximum pool size: "+ tExecutor.getMaximumPoolSize());
                 tExecutor.submit(task1); tExecutor.submit(task2); 
                 tExecutor.execute(task1); // start task1
                 tExecutor.execute(task2); // start task2    
                 System.out.println("get rejected exception handler :"+ tExecutor.getRejectedExecutionHandler());
                 tExecutor.shutdown(); // shutdown worker threads
                 System.out.println("Threads started, main ends\n");
                }
       }

 class Work23 implements Runnable {
 
        private final String threadName; 
        public Work23(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(Work23.class.getName()).log(Level.SEVERE, null, ex);
              }
          }
          else{
              System.out.println(" now  i > 5 :");
              break;
          }
      }
}
}

Test it Now

Output:

Starting threads
  Maximum pool size: 2147483647
Thread sleeping for 1000 i=0
Thread sleeping for 1000 i=0
get rejected exception handler :java.util.concurrent.ThreadPoolExecutor$AbortPolicy@3d4eac69
Threads started, main ends

Thread sleeping for 1000 i=0
Thread sleeping for 1000 i=0
Thread sleeping for 1000 i=1
Thread sleeping for 1000 i=1
Thread sleeping for 1000 i=1
Thread sleeping for 1000 i=1
Thread sleeping for 1000 i=2
Thread sleeping for 1000 i=2
Thread sleeping for 1000 i=2
Thread sleeping for 1000 i=2
Thread sleeping for 1000 i=3
Thread sleeping for 1000 i=3
Thread sleeping for 1000 i=3
Thread sleeping for 1000 i=3
Thread sleeping for 1000 i=4
Thread sleeping for 1000 i=4
Thread sleeping for 1000 i=4
Thread sleeping for 1000 i=4
 now  i > 5 :
 now  i > 5 :
 now  i > 5 :
 now  i > 5 :

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