Callable和Runnable接口的区别

区别1: 两者最大的区别，实现Callable接口的任务线程能返回执行结果，而实现Runnable接口的任务线程不能返回执行结果

注意点：Callable接口支持返回执行结果，此时需要调用FutureTask.get()方法实现，此方法会阻塞线程直到获取“将来”的结果，当不调用此方法时，主线程不会阻塞

区别2:Callable接口实现类中run()方法允许将异常向上抛出，也可以直接在内部处理(try...catch); 而Runnable接口实现类中run()方法的异常必须在内部处理掉，不能向上抛出

Demo1: Callable接口测试
package com.cc.io.currentthread;

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

public class CallableTest {
public static void main(String[] args) throws ExecutionException, InterruptedException {
Callable callable = new CallableImpl(" my callable test");
FutureTask task = new FutureTask<>(callable);

    Long beginTime = System.currentTimeMillis();
    new Thread(task).start();
    String result = task.get();
    Long endTime = System.currentTimeMillis();
    System.out.println("hello," + result);
    System.out.println("cast:" + (endTime-beginTime)/1000);


}

}

class CallableImpl implements Callable {

private String str;

public CallableImpl(String str) {
    this.str = str;
}

@Override
public String call() throws Exception {
    Thread.sleep(1000);
    return this.str + " append some chars and return it";
}

}

Demo2: Runnable接口测试
package com.cc.io.currentthread;

public class RunnableTest {
public static void main(String[] args) {
Runnable runnable = new RunnableImpl("my runnable test");
Long beginTime = System.currentTimeMillis();
new Thread(runnable).start();
Long endTime = System.currentTimeMillis();
System.out.println("cast:" + (endTime-beginTime)/1000);
}
}

class RunnableImpl implements Runnable {

private String str;

public RunnableImpl(String str) {
    this.str = str;
}

@Override
public void run() {
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println("hello:" + this.str);
}

}