题目要求
有三个数组如下:
int[] arr1 = new int[]{1,2,3};
int[] arr2 = new int[]{4,5,6};
int[] arr3 = new int[]{7,8,9};
使用多线程,对数组相加,如arr1=6,arr2=15,arr3=24。然后进行6+15+24=45。
要点
多线程运算后获取返回值,Runnable没有返回对象,我们要使用Callable,中Callable中有call方法可以返回线程运行后的结果。
Callable是一种具有类型参数的泛型,它的类型参数表的是从方法call()中返回的值,并且必须使用ExecutorServices.submit()方法调用它
实现
ArrayCallable
public class ArrayCallable implements Callable {
//接收数组
private int[] arr;
//接收名称
private String name;
//和运算结果
private int total = 0;
public ArrayCallable(int[] arr, String name) {
this.arr = arr;
this.name = name;
}
@Override
public Object call() throws Exception {
//和运算
for(int i:arr){
System.out.println(name+":子线程在进行计算"+i);
total += i;
System.out.println(name+":子线程在进行计算和为"+total);
}
return total;
}
}
创建线程池,通过Future方法获取返回值
我们可以看看源码提供返回值的方法,是返回Future
<T> Future<T> submit(Callable<T> task);
<T> Future<T> submit(Runnable task, T result);
Future<?> submit(Runnable task);
我们使用第一个方法
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/**
* @author liuzonghua
* @Package top.maniy.util.Thread
* @Description:
* @date 2020/5/14 9:29
*/
public class Client {
public static void main(String[] args) {
int total = 0;
int[] arr1 = new int[]{1,2,3};
int[] arr2 = new int[]{4,5,6};
int[] arr3 = new int[]{7,8,9};
//创建一个线程池
ExecutorService pool = Executors.newCachedThreadPool();
//callable实例
ArrayCallable callable = new ArrayCallable(arr1,"第一个数组");
//执行任务并获取Future对象
Future<Integer> result = pool.submit(callable);
ArrayCallable callable2 = new ArrayCallable(arr2,"第二个数组");
Future<Integer> result2 = pool.submit(callable2);
ArrayCallable callable3 = new ArrayCallable(arr3,"第三个数组");
Future<Integer> result3 = pool.submit(callable3);
//关闭线程池
pool.shutdown();
try {
//输出任务结果
System.out.println("task运行结果"+result.get());
System.out.println("task运行结果"+result2.get());
System.out.println("task运行结果"+result3.get());
total = result.get()+result2.get()+result3.get();
System.out.println(total);
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}