代码demo:
import java.util.concurrent.*;
public class ForkJoinDemo {
static class RecursiveTaskA extends RecursiveTask<String> {
@Override
protected String compute() {
try {
System.out.println(Thread.currentThread().getName() + "开始运行:" + System.currentTimeMillis());
TimeUnit.SECONDS.sleep(3);
System.out.println(Thread.currentThread().getName() + "结束运行:" + System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
return "A";
}
}
static class RecursiveTaskB extends RecursiveTask<String> {
@Override
protected String compute() {
try {
System.out.println(Thread.currentThread().getName() + "开始运行:" + System.currentTimeMillis());
TimeUnit.SECONDS.sleep(1);
System.out.println(Thread.currentThread().getName() + "结束运行:" + System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
return "B";
}
}
public static void main(String[] args) {
ForkJoinPool forkJoinPool = new ForkJoinPool(2);
ForkJoinTask<String> futureTaskA = forkJoinPool.submit(new RecursiveTaskA());
ForkJoinTask<String> futureTaskB = forkJoinPool.submit(new RecursiveTaskB());
System.out.println("准备打印:" + System.currentTimeMillis());
System.out.println(System.currentTimeMillis() + ":A=" + futureTaskA.join());
System.out.println(System.currentTimeMillis() + ":B=" + futureTaskB.join());
}
}
运行结果:
可以发现任务A和任务B是异步进行的,但是使用了join()方法,最终变成同步返回。