【Java笔记】多线程实现简单的异步运算

实现Callable接口，重写call（）方法，使操作线程池时能带有返回值的效果：

import java.util.concurrent.Callable;

public class GetSumCallable implements Callable<Integer> {
	private int a;

	public GetSumCallable(int a) {
		this.a = a;
	}

	public Integer call() {
		int sum = 0;
		for (int i = 1; i <= a; i++)
			sum += i;
		return sum;
	}
}

将线程放入线程池中，实现异步运算：

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

public class GetSumThreadPoolDemo {
	public static void main(String[] args) throws Exception, ExecutionException {
		// 创建一个线程数为2的线程池
		ExecutorService es = Executors.newFixedThreadPool(2);
		// 将线程放入线程池中运行，将返回值封装成Future接口实现类对象
		Future<Integer> f1 = es.submit(new GetSumCallable(100));
		Future<Integer> f2 = es.submit(new GetSumCallable(200));
		// 调用Future接口实现类对象，获得封装的值并输出
		System.out.println(f1.get());
		System.out.println(f2.get());
		// 销毁线程池
		es.shutdown();
	}
}