Runnable和Callable之间的区别

Runnable和Callable之间的区别

1、Runnable任务执行后没有返回值；Callable任务执行后可以获得返回值

2、Runnable的方法是run()，没有返回值；Callable的方法是call()，有返回值

3、Runnable的run()方法不能抛异常，有异常的话只能在run方法里面解决；Callable的call()方法可以抛异常

4、Runnable可以直接传递给Thread对象执行；Callable不可以，Callable执行可以放在FutureTask中，然后把futureTask传递给Thread执行

这里只关注了异常的捕捉：

package com.qjc.thread.runandcall;

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

public class RunnableAndCallable {

    public static void main(String[] args) {
        // Runnable可以直接传递给Thread对象执行
        new Thread(new RunnableThread()).start();
        // 查看FutureTask源码最终集继承是Runnable, Future<V>接口，所以可通过Excutor(线程池) 来执行,也可传递给Thread对象执行。
        FutureTask<String> futureTask = new FutureTask<>(new CallableThread());
        new Thread(futureTask).start();
        String string = null;
        try {
            string = futureTask.get();
        } catch (InterruptedException e) {
            string = "InterruptedException";
            e.printStackTrace();
        } catch (ExecutionException e) {
            string = "ExecutionException";
            e.printStackTrace();
        }
        System.out.println("CallableThread输出:" + string);
    }
}

class RunnableThread implements Runnable {
    @Override
    public void run() {
        int a = 0;
        try {
            a = 100 / 0;
            System.out.println("RunnableThread输出:" + a);
        } catch (Exception e) {
            System.err.println("RunnableThread出异常了");
            e.printStackTrace();
        }
    }
}

class CallableThread implements Callable<String> {
    @Override
    public String call() throws Exception {
        int a = 100 / 1;
        return String.valueOf(a);
    }
}