Question

1）在Java无连接套接字编程中，如何确保来自我的5个处理器的所有数据包都已收到并在它们到达时存储在数组中？基本上，我想收集作为多播组一部分的所有进程（其中5个）发送的所有部分和，并将这些部分和存储在一个数组中，然后我将执行一些操作。

2）另外，我很感激如何在同一代码中找到整数数组的给定元素的索引。我需要执行的操作之一是找到我的数组的Max并检索其索引。

下面是我的线程代码片段，其中包含接收方法。

readThread(InetAddress g, int port){

    group = g;
    multicastPort = port;
}

public void run(){

    try {
        MulticastSocket readSocket = new MulticastSocket(multicastPort);
        readSocket.joinGroup(group);

        while (true) {
            byte[] recvBuffer = new byte[MAX_MSG_LEN];
            DatagramPacket packet = new DatagramPacket(recvBuffer, recvBuffer.length, group, multicastPort);

            readSocket.receive(packet);

            String rString = new String(packet.getData());
            String message = new String(rString.getBytes()).trim();                             // Process the received message before use here

            StringTokenizer stk = new StringTokenizer(message, ",");

            int recvdProcessID = Integer.parseInt(stk.nextToken());
            int recvdPartialSum = Integer.parseInt(stk.nextToken());

            System.out.println("\n"+recvdProcessID+" "+recvdPartialSum);

            int[] arrayPartialSum = new int[multicastSenderReceiver.numProcesses];              // array to store partial sums

            /* Store each received partial sum in an array of partial 
             sums at index corresponding to the respective */

            arrayPartialSum[recvdProcessID] = recvdPartialSum;

            // For debug, here is another way of listing the elements of the array of partial sums.
            System.out.println("\nHere is the array of partial sums: ");
            for (int element: arrayPartialSum){
                System.out.println("\n"+element);
            }

            // Compute and Display the sum of all the partial sums:
            int grandTotal = 0;
            for (int s: arrayPartialSum) {
                grandTotal += s;
            }
            System.out.println("\nGrand Total: "+grandTotal);

            /*Finding the maximum value in the array of partial sums */
            int maximumSum = 0;
            maximumSum = maximum.Max(arrayPartialSum);
            System.out.println("The Maximum of all partial sums is"+maximumSum);
        }

    }
    catch (Exception e) {
        e.printStackTrace();
    }
}
}

更新：我从while（true）循环中移出了一些元素，但现在我在编译时遇到了一种新的错误。它显示某些行并说“无法访问的声明”。有什么想法吗？

public void run(){

    try {
        MulticastSocket readSocket = new MulticastSocket(multicastPort);
        readSocket.joinGroup(group);
        int[] arrayPartialSum = new int[multicastSenderReceiver.numProcesses];              // array to store partial sums
        int grandTotal = 0;

        while (true) {
            byte[] recvBuffer = new byte[MAX_MSG_LEN];
            DatagramPacket packet = new DatagramPacket(recvBuffer, recvBuffer.length, group, multicastPort);

            readSocket.receive(packet);

            String rString = new String(packet.getData());
            String message = new String(rString.getBytes()).trim();                             // Process the received message before use here

            StringTokenizer stk = new StringTokenizer(message, ",");

            int recvdProcessID = Integer.parseInt(stk.nextToken());
            int recvdPartialSum = Integer.parseInt(stk.nextToken());

            System.out.println("\n"+recvdProcessID+" "+recvdPartialSum);

            /* Store each received partial sum in an array of partial 
             sums at index corresponding to the respective */
            arrayPartialSum[recvdProcessID] = recvdPartialSum;
        }

        // Compute and Display the sum of all the partial sums:
        for (int s: arrayPartialSum) {
            grandTotal += s;
        }
        System.out.println("\nGrand Total: "+grandTotal);

        /*Finding the maximum value in the array of partial sums */
        int maximumSum = 0;
        maximumSum = maximum.Max(arrayPartialSum);
        System.out.println("The Maximum of all partial sums is"+maximumSum);

        // For debug, here is another way of listing the elements of the array of partial sums.
        System.out.println("\nHere is the array of partial sums: ");
        for (int element: arrayPartialSum){
            System.out.println("\n"+element);
        }

    }
    catch (Exception e) {
        e.printStackTrace();
    }
}

Answer 1

我终于重新访问了我的源代码并理解代码实际上是有用的，即。好。可以进行一些调整以使其更漂亮并改善逻辑。例如，我将一些变量声明从无限循环中移出......

我的问题的答案非常简单：

行arrayPartialSum[recvdProcessID] = recvdPartialSum;实际上做了它应该做的事情。也就是说，将每个接收到的部分和存储在与其进程ID相对应的索引处的部分和数组中。逻辑中的问题实际上并不在代码中，而是作为程序用户的方式启动流程。我需要确保在每个进程中都返回它，以便将其部分总和发送到多播组。

要检索给定项目的索引，下面的代码执行作业，maximumSum是其索引尝试在数组arrayPartialSum中找到的元素：

for (int i = 0; i < arrayPartialSum.length; i++) {
    if (arrayPartialSum[i] == maximumSum) {
        retval = i;
        break;
    }
}

如何确保所有数据包都已接收并存储在阵列中？

1 个答案: