Java future callable example 2016-12-05 21:18
In this blog I will show you how to use Future and Callable to get the result asynchronously. Write your logic code in call method of Callable then submit it and get Future. isDone method in Future class can help you to get the result of your task. get method of Future class will get the result of your task, this method will block the thread if the task doesn't finish. Sample code is like following.
Task class
class Task implements Callable<String> {
public String call() throws Exception {
System.out.println("this is task class , I am running");
Thread.sleep(2000);
System.out.println("this is task class , I am stopping");
return "task result";
}
}
Client
public class FutureClient {
public static void main(String[] args) throws Exception {
Task task = new Task();
ExecutorService es = Executors.newCachedThreadPool();
Future future = es.submit(task);
System.out.println("this is main thread, after submitting callable class. state of task:" + future.isDone());
Thread.sleep(3000);
System.out.println("this is main thread, after 3 seconds. state of task:" + future.isDone());
Thread.sleep(2000);
System.out.println("the result of task class:" + future.get());
es.shutdownNow();
}
}
The output is like following.
this is main thread, after submitting callable class. state of callable:false
this is callable class , I am running
this is callable class , I am stopping
this is main thread, after 3 seconds. state of callable:true
the result of callable class:callable result