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What is FutureTask Class?

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Pragya Keshap answered on February 22, 2023 Popularity 1/10 Helpfulness 1/10

answer What is FutureTask Class?

What is FutureTask Class?

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FutureTask is the base implementation class of Future interface

and we can use it with Executors for asynchronous processing.

Most of the time we don’t need to use FutureTask class but it comes real handy

if we want to override some of the methods of Future interface and want to keep most of the base implementation.

We can just extend this class and override the methods according to our requirements.

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class FutureTaskExample {

	public static void main(String[] args) {
		MyCallable callable1 = new MyCallable(1000);
		MyCallable callable2 = new MyCallable(2000);

		FutureTask<String> futureTask1 = new FutureTask<String>(callable1);
		FutureTask<String> futureTask2 = new FutureTask<String>(callable2);

		ExecutorService executor = Executors.newFixedThreadPool(2);
		executor.execute(futureTask1);
		executor.execute(futureTask2);
		
		while (true) {
			try {
				if(futureTask1.isDone() && futureTask2.isDone()){
					System.out.println("Done");
					//shut down executor service
					executor.shutdown();
					return;
				}
				
				if(!futureTask1.isDone()){
				//wait indefinitely for future task to complete
				System.out.println("FutureTask1 output="+futureTask1.get());
				}
				
				System.out.println("Waiting for FutureTask2 to complete");
				String s = futureTask2.get(200L, TimeUnit.MILLISECONDS);
				if(s !=null){
					System.out.println("FutureTask2 output="+s);
				}
			} catch (InterruptedException | ExecutionException e) {
				e.printStackTrace();
			}catch(TimeoutException e){
				//do nothing
			}
		}
		
	}

}

https://www.digitalocean.com/community/tutorials/java-futuretask-example-program

Popularity 1/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: futuretask java

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Contributed on Feb 22 2023

Pragya Keshap

0 Answers Avg Quality 2/10

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