Java线程池，isShutDown、isTerminated的作用与区别

isShutDown当调用shutdown()或shutdownNow()方法后返回为true。 

isTerminated当调用shutdown()方法后，并且所有提交的任务完成后返回为true;

isTerminated当调用shutdownNow()方法后，成功停止后返回为true;

如果线程池任务正常完成，都为false

import java.util.concurrent.Callable;

/**
* Title: ShortTask
* Description:
* @date 2018/1/28 17:32
*/
public class ShortTask implements Callable {
@Override
public Object call() throws Exception {
System.out.println("短任务");
return null;
}
}

import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;

/**
* Title: LongTask
* Description:
* @date 2018/1/28 17:33
*/
public class LongTask implements Callable {
@Override
public Object call() throws Exception {
System.out.println("长任务");
TimeUnit.SECONDS.sleep(5);
return null;
}
}

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class Main {

public static void main(String[] args) {
ScheduledExecutorService service = Executors.newScheduledThreadPool(4);
service.submit(new ShortTask());
service.submit(new ShortTask());
service.submit(new LongTask());
service.submit(new ShortTask());
System.out.println("isShutdown:" + service.isShutdown());
System.out.println("isTerminated:" + service.isTerminated());
service.shutdown();
//        List<Runnable> list = service.shutdownNow();
//        System.out.println(list.size());
System.out.println("isShutdown:" + service.isShutdown());
System.out.println("isTerminated:" + service.isTerminated());
try {
while (!service.awaitTermination(1, TimeUnit.SECONDS)) {
System.out.println("线程池没有关闭");
System.out.println("isTerminated:" + service.isTerminated());
}
} catch (InterruptedException e) {
e.printStackTrace();
}

System.out.println("线程池已经关闭");
System.out.println("isTerminated:" + service.isTerminated());
}
}

/*
执行service.shutdown();
短任务
短任务
长任务
短任务
isShutdown:false
isTerminated:false
isShutdown:true
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池已经关闭
isTerminated:true*/

/*
执行List<Runnable> list = service.shutdownNow();
System.out.println(list.size());
短任务
短任务
长任务
isShutdown:false
isTerminated:false
1
isShutdown:true
isTerminated:false
线程池已经关闭
isTerminated:true
*/

/*
如果不执行shutdown，也不执行shutdownNow：
短任务
短任务
长任务
短任务
isShutdown:false
isTerminated:false
isShutdown:false
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
线程池没有关闭
isTerminated:false
......一直这样输出
*/

英文好的可继续参考源码：

/**
* Returns {@code true} if this executor has been shut down.
*
* @return {@code true} if this executor has been shut down
*/
boolean isShutdown();

/**
* Returns {@code true} if all tasks have completed following shut down.
* Note that {@code isTerminated} is never {@code true} unless
* either {@code shutdown} or {@code shutdownNow} was called first.
*
* @return {@code true} if all tasks have completed following shut down
*/
boolean isTerminated();