java - Java 中的并行线程

Question

好的，所以我正在尝试查找二维数组的最大元素。我将有一个方法接受 2darray 作为参数并找到最大值。它需要找到每一行的最大元素作为一个单独的线程，以便线程并行运行，然后加入每个线程，并找到其中的最大值以获得整个二维数组的最大值。现在我遇到的问题是 run() 不返回任何值...那么我应该如何访问已修改的值。例如

public static int maxof2darray(long[][] input){


ArrayList<Thread> threads = new ArrayList<Thread>();
long[]rowArray;
for(int i=0; i<input.length; i++){
rowArray = input[i];
teste r1 = new teste(rowArray,max);
threads.add(new Thread(r1));
}

for ( Thread x : threads )
    {
        x.start();

    }
try {


for ( Thread x : threads)
{
      x.join();
}
}

如您所见，它创建了一个线程对象数组列表。然后获取每一行并调用找到该行最大值的 run() 函数...问题是 run() 不返回任何值...那么我怎么可能访问该行的最大值？

Answer 1

Future API应该做你需要的。

A Future represents the result of an asynchronous computation. Methods are provided to check if the computation is complete, to wait for its completion, and to retrieve the result of the computation. The result can only be retrieved using method get when the computation has completed, blocking if necessary until it is ready. Cancellation is performed by the cancel method. Additional methods are provided to determine if the task completed normally or was cancelled. Once a computation has completed, the computation cannot be cancelled. If you would like to use a Future for the sake of cancellability but not provide a usable result, you can declare types of the form Future and return null as a result of the underlying task.