package inverview.callable;

import java.util.Random;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.FutureTask;

public class CallableFutureTest {

public static void main(String[] args) throws InterruptedException, ExecutionException {

// FutureTask is a concrete class that implements both Runnable and Future

FutureTask<Integer>[] randomNumberTasks = new FutureTask[5];

for (int i = 0; i < 5; i++) {

Callable<Integer> callable = new CallableExample();

// Create the FutureTask with Callable

randomNumberTasks[i] = new FutureTask<Integer>(callable);

// As it implements Runnable, create Thread

// with FutureTask

Thread t = new Thread(randomNumberTasks[i]);

t.start();

}

for (int i = 0; i < 5; i++) {

// As it implements Future, we can call get()

System.out.println(randomNumberTasks[i].get());

// This method blocks till the result is obtained

// The get method can throw checked exceptions

// like when it is interrupted. This is the reason

// for adding the throws clause to main

}

}

}

class CallableExample implements Callable<Integer> {

public Integer call() throws Exception {

Random generator = new Random();

Integer randomNumber = generator.nextInt(10);

Thread.sleep(randomNumber * 1000);

return randomNumber;

}

}