Java ThreadPoolExecutor toString() Method

The toString() method of ThreadPoolExecutor class returns the string representation of the ThreadPoolExecutor object.

Syntax

Parameters

Return

A string identifying this pool, as well as its state

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 ThreadPoolExecutortoStringExample1    {
            public static void main(final String[] arguments) throws InterruptedException {
                     ThreadPoolExecutor executor = (ThreadPoolExecutor)Executors.newCachedThreadPool();
                     executor.submit(new Task());
                     executor.submit(new Task());
                     executor.shutdown();
                     System.out.println(" toString :"+ executor.toString());
               }  
      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:

toString :java.util.concurrent.ThreadPoolExecutor@33909752[Shutting down, pool size = 2, active threads = 2, queued tasks = 0, completed tasks = 0]
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 ThreadPoolExecutortoStringExample2  {
     public static void main(String[] args) {
                 WorkD task1 = new WorkD("t1");    
                 System.out.println("Starting threads");
                 ThreadPoolExecutor tExecutor = (ThreadPoolExecutor) Executors.newCachedThreadPool();
                 tExecutor.submit(task1); 
                 tExecutor.execute(task1); // start task1
                 tExecutor.shutdown(); // shutdown worker threads
                 System.out.println(" toString :"+ tExecutor.toString());
         }
}

 class WorkD implements Runnable {
  private final String threadName;
 public WorkD(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:

Starting threads
i=5
i=5
 toString :java.util.concurrent.ThreadPoolExecutor@55f96302[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 2]

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