jdk1.6中添加的future-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_13304/article/details/81601409

本文介绍了一个使用Java并发编程技术实现的素数计算程序。通过定义一个实现了Callable接口的PrimeCallable类来计算指定范围内的所有素数，并利用FutureTask和Thread进行异步任务调度。最后展示如何获取并打印计算结果。

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摘自：http://caterpillar.onlyfun.net/Gossip/JavaGossip-V2/CallableFuture.htm

package onlyfun.caterpillar;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;

public class PrimeCallable implements Callable<int[]> {
	private int max;

	public PrimeCallable(int max) {
		this.max = max;
	}

	public int[] call() throws Exception {
		int[] prime = new int[max + 1];

		List<Integer> list = new ArrayList<Integer>();

		for (int i = 2; i <= max; i++)
			prime[i] = 1;

		for (int i = 2; i * i <= max; i++) {
			if (prime[i] == 1) {
				for (int j = 2 * i; j <= max; j++) {
					if (j % i == 0)
						prime[j] = 0;
				}
			}
		}

		for (int i = 2; i < max; i++) {
			if (prime[i] == 1) {
				list.add(i);
			}
		}

		int[] p = new int[list.size()];
		for (int i = 0; i < p.length; i++) {
			p[i] = list.get(i).intValue();
		}

		return p;
	}
}

package onlyfun.caterpillar;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class FutureDemo {
	public static void main(String[] args) {
		Callable<int[]> primeCallable = new PrimeCallable(1000);
		FutureTask<int[]> primeTask = new FutureTask<int[]>(primeCallable);

		Thread t = new Thread(primeTask);
		t.start();

		try {
			Thread.sleep(5000);

			if (primeTask.isDone()) {
				int[] primes = primeTask.get();
				for (int prime : primes) {
					System.out.print(prime + " ");
				}
				System.out.println();
			}
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
	}
}