【JAVA-线程】Callable接口和线程池创建线程

一。Callable

步骤:

1.创建一个实现Callable接口的实现类

class CallableTest implements Callable{}

2.在Callable接口实现类中实现call（）方法

public Object call() throws Exception{
	
	return null;
}

3.创建Callable实现类对象

CallableTest callable = new CallableTest();

4.将Callable实现类对象 传递到FutureTask中,生成FutureTask对象

FutureTask futureTask = new FutureTask(callable);

5.将FutureTask对象传递到Thread构造器中，生成Thread对象并.start()调用

new Thread（futureTask）.start();

6.如果需要call()方法的返回值，使用futureTask.get（）

try {
			//get 返回为call（）方法的返回值
			Object sum=futureTask.get();
			System.out.println(sum);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ExecutionException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

代码：

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

//1。创建一个实现Callable接口的实现类
class NumThread implements Callable{
	//2.实现call方法
	@Override
	public Object call() throws Exception {
		int sum=0;
		for(int i=1;i<=100;i++) {
			if(i%2==0) {
				System.out.println(i+"是偶数");
				sum +=i;
				}
		}
		
		return sum;
	}
	
}
public class CallableDemo {
	public static void main(String[] args) {
		//3创建Callable接口实现类的对象
		NumThread thread =new NumThread();
		//4.将此Callable实现对象传递到FutureTask构造器中，创建FutureTask杜希昂
		FutureTask futuretask = new FutureTask(thread);
		//5.将FutureTask对象作为参数传递到Thread类构造器中，创建Thread对象，.start()方法调用
		new Thread(futuretask).start();
	
		try {
			//get 返回为call方法的返回值
			//6.获取Callable 中 call（）方法的返回值
			Object sum=futuretask.get();
			System.out.println(sum);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ExecutionException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

二。线程池

代码：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

class PoolThread implements Runnable{
	@Override
	public void run() {
		int sum=0;
		for(int i=1;i<=100;i++) {
			if(i%2==0) {
				System.out.println(Thread.currentThread().getName()+"..."+i+"是偶数");
				sum +=i;
				}
		}
	}
}
public class ThreadPool {
	public static void main(String[] args) {
		ExecutorService service =Executors.newFixedThreadPool(10);
		service.execute(new PoolThread());//适合使用Runnable
	//	service.submit();//适合使用Callable
		service.shutdown();
	}
}