Runnable与Callable区别
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相同点:
- 两者都是接口;(废话)
- 两者都可用来编写多线程程序;
- 两者都需要调用Thread.start()启动线程;
不同点:
- 两者最大的不同点是: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结果;
- Callable接口的call()方法允许抛出异常;而Runnable接口的run()方法的异常只能在内部消化,不能继续上抛;
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,此方法会阻塞主线程直到获取‘将来’结果;当不调用此方法时,主线程不会阻塞!
Callable工作的Demo:
package com.callable.runnable;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
/**
* Created on 2016/5/18.
*/
public class CallableImpl implements Callable<String> {
public CallableImpl(String acceptStr) {
this.acceptStr = acceptStr;
}
private String acceptStr;
@Override
public String call() throws Exception {
// 任务阻塞 1 秒
Thread.sleep(1000);
return this.acceptStr + " append some chars and return it!";
}
public static void main(String[] args) throws ExecutionException, InterruptedException {
Callable<String> callable = new CallableImpl("my callable test!");
FutureTask<String> task = new FutureTask<>(callable);
long beginTime = System.currentTimeMillis();
// 创建线程
new Thread(task).start();
// 调用get()阻塞主线程,反之,线程不会阻塞
String result = task.get();
long endTime = System.currentTimeMillis();
System.out.println("hello : " + result);
System.out.println("cast : " + (endTime - beginTime) / 1000 + " second!");
}
}
Runnable的Demo
package com.callable.runnable;
/**
* Created on 2016/5/18.
*/
public class RunnableImpl implements Runnable {
public RunnableImpl(String acceptStr) {
this.acceptStr = acceptStr;
}
private String acceptStr;
@Override
public void run() {
try {
// 线程阻塞 1 秒,此时有异常产生,只能在方法内部消化,无法上抛
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 最终处理结果无法返回
System.out.println("hello : " + this.acceptStr);
}
public static void main(String[] args) {
Runnable runnable = new RunnableImpl("my runable test!");
long beginTime = System.currentTimeMillis();
new Thread(runnable).start();
long endTime = System.currentTimeMillis();
System.out.println("cast : " + (endTime - beginTime) / 1000 + " second!");
}
}
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