題目要求
有三個數組如下:
int[] arr1 = new int[]{1,2,3};
int[] arr2 = new int[]{4,5,6};
int[] arr3 = new int[]{7,8,9};
使用多線程,對數組相加,如arr1=6,arr2=15,arr3=24。然後進行6+15+24=45。
要點
多線程運算後獲取返回值,Runnable沒有返回對象,我們要使用Callable,中Callable中有call方法可以返回線程運行後的結果。
Callable是一種具有類型參數的泛型,它的類型參數表的是從方法call()中返回的值,並且必須使用ExecutorServices.submit()方法調用它
實現
ArrayCallable
public class ArrayCallable implements Callable {
//接收數組
private int[] arr;
//接收名稱
private String name;
//和運算結果
private int total = 0;
public ArrayCallable(int[] arr, String name) {
this.arr = arr;
this.name = name;
}
@Override
public Object call() throws Exception {
//和運算
for(int i:arr){
System.out.println(name+":子線程在進行計算"+i);
total += i;
System.out.println(name+":子線程在進行計算和爲"+total);
}
return total;
}
}
創建線程池,通過Future方法獲取返回值
我們可以看看源碼提供返回值的方法,是返回Future
<T> Future<T> submit(Callable<T> task);
<T> Future<T> submit(Runnable task, T result);
Future<?> submit(Runnable task);
我們使用第一個方法
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};
//創建一個線程池
ExecutorService pool = Executors.newCachedThreadPool();
//callable實例
ArrayCallable callable = new ArrayCallable(arr1,"第一個數組");
//執行任務並獲取Future對象
Future<Integer> result = pool.submit(callable);
ArrayCallable callable2 = new ArrayCallable(arr2,"第二個數組");
Future<Integer> result2 = pool.submit(callable2);
ArrayCallable callable3 = new ArrayCallable(arr3,"第三個數組");
Future<Integer> result3 = pool.submit(callable3);
//關閉線程池
pool.shutdown();
try {
//輸出任務結果
System.out.println("task運行結果"+result.get());
System.out.println("task運行結果"+result2.get());
System.out.println("task運行結果"+result3.get());
total = result.get()+result2.get()+result3.get();
System.out.println(total);
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}