Java: Set time out on specific block of code

Implement an application such that, it throws an Exception if given block of code runs longer acceptable.

Using 'Future.get' method, we can solve this problem.

V get(long timeout, TimeUnit unit)cthrows InterruptedException, ExecutionException,cTimeoutException

Waits if necessary for at most the given time for the computation to complete, and then retrieves its result, if available. It throws, TimeoutException, if the wait timed out.

Step 1: Create Runnable task.

Runnable task = new Runnable() {

         public void run() {

                  try {

                           while (true) {

                                    Thread.sleep(1000);

                                    System.out.println("Hi");

                           }

                  } catch (Exception e) {

                  }

         }

};

Step 2: Submit the task to a thread pool.

ExecutorService executor = Executors.newSingleThreadExecutor();

Future<?> future = executor.submit(task);

Step 3: Use get method to wait until the task is finished.

try {

         future.get(5, TimeUnit.SECONDS);

} catch (TimeoutException e) {

         System.out.println("Task is taking more than 5 seconds");

         System.out.println("Exiting the execution of task");

         if (!executor.isTerminated())

                  executor.shutdownNow();

}

As you see above snippet, I shutdown the executor when the task took more than 5 seconds.

App.java

package com.sample.app;

import java.io.IOException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class App {
 private static final ExecutorService executor = Executors.newSingleThreadExecutor();

 public static void main(String args[]) throws IOException {
  Runnable task = new Runnable() {
   public void run() {
    try {
     while (true) {
      Thread.sleep(1000);
      System.out.println("Hi");
     }
    } catch (Exception e) {

    }
   }
  };

  Future<?> future = executor.submit(task);

  try {
   future.get(5, TimeUnit.SECONDS);
  } catch (TimeoutException e) {
   System.out.println("Task is taking more than 5 seconds");
   System.out.println("Exiting the execution of task");
   if (!executor.isTerminated())
    executor.shutdownNow();
  } catch (Exception e) {
   e.printStackTrace();
  }

 }
}

Output

Hi

Hi

Hi

Hi

Task is taking more than 5 seconds

Exiting the execution of task

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