package currentTest.BlockingQueue;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.FutureTask;

/**

 * 测试FutureTask的用法，如果不想分支线程阻塞主线程，又想取得分支线程的执行结果，就用FutureTask

 *

 * @author zhailzh

 *

 */

public class FutureTaskTest {

    /**

     * @param args

     */

    public static void main(String[] args) {

        CountNum cn = new CountNum(0);

        // FutureTask<Integer> 这里的表示返回的是Integer

        FutureTask<Integer> ft = new FutureTask<Integer>(cn);

        Thread td = new Thread(ft);

        System.out.println("futureTask执行计算:" + System.currentTimeMillis());

        td.start();

        System.out.println("main 主线程可以做些其他事情" + System.currentTimeMillis());

        try {

            // futureTask的get方法会阻塞，知道可以取得结果为止

            Integer result = ft.get();

            System.out.println("计算的结果是:" + result);

        } catch (InterruptedException e) {

            e.printStackTrace();

        } catch (ExecutionException e) {

            e.printStackTrace();

        }

        System.out.println("取得分支线程执行的结果后，主线程可以继续处理其他事项");

    }

}

class CountNum implements Callable {

    private Integer sum;

    public CountNum(Integer sum) {

        this.sum = sum;

    }

    public Object call() throws Exception {

        for (int i = 0; i < 100; i++) {

            sum = sum + i;

        }

        // 休眠5秒钟，观察主线程行为，预期的结果是主线程会继续执行，到要取得FutureTask的结果是等待直至完成

        Thread.sleep(3000);

        System.out.println("futureTask 执行完成" + System.currentTimeMillis());

        return sum;

    }

}