Callable

Callable

1. 可以有返回值
2. 可以抛出异常
3. 方法 call()

public class CallableTest {

    public static void main(String[] args) throws InterruptedException, ExecutionException {
        MyCallable myCallable = new MyCallable();
        FutureTask task = new FutureTask<>(myCallable);
        new Thread(task, "tname1").start();
        new Thread(task, "tname2").start(); // 结果会被缓存，多次调用call方法只执行一次
        // 获取callable返回结果  get方法可能产生阻塞
        String str = (String) task.get(); 
        System.out.println(str);
    }
}

class MyCallable implements Callable<String> {

    @Override
    public String call() throws Exception {
        System.out.println("call runs..");
        return "hello world";
    }
}