检测服务器套接字关闭

Question

I am trying to send some numbers between client and server. Before closing the server, I am sending the string "End". The client checks if the string it is reading is "End" or not. If no, it will capture the string. However, I am facing two issues with it. First, I am sending 7 numbers but for some reason, getting four numbers (every other number). For example, I am sending these numbers from server: [79, 20, 42, 0, 10, 31, 21] and getting these numbers in client: [79, 42, 10, 21]. Second, I am getting an EOFException, even though I am checking the object.

The server code is below:

public class main {

public static void main(String[] args) throws IOException {

    // Create a Socket
    int port = 6000;
    @SuppressWarnings("resource")
    ServerSocket sersock = new ServerSocket(port);
    Socket sock = sersock.accept( );

    OutputStream ostream = sock.getOutputStream(); 
    ObjectOutputStream pwrite = new ObjectOutputStream(ostream);

    int q = 7;

    SecureRandom rand = new SecureRandom();
    int[] list = new int [q];

    for (int i = 0; i < q; i++)
    {
        int num = rand.nextInt(100);
        list[i] = num;
        String n1 =  Integer.toString(num);
        pwrite.writeObject(n1);
    }
    System.out.println(Arrays.toString(list));

    // Close the socket
    pwrite.writeObject("End");
    sock.close();
}

}

The client code is below:

public class main {

public static void main(String[] args) throws UnknownHostException, IOException, ClassNotFoundException {
    // Create Socket
    int port = 6000;
    Socket sock = new Socket("localhost", port);
    ObjectInputStream ois = new ObjectInputStream(sock.getInputStream());
    String test = "";
    ArrayList<String> numlist = new ArrayList<String>();

    //while(! sock.isClosed())
    while((test = (String) ois.readObject()) != "End")
    {
        System.out.println(test);
        Object n1 = ois.readObject();
        if(n1 instanceof String)
        {
            String n2 = (String) n1;
            numlist.add(n2);
        }
    }

    System.out.println("The collected clues are: ");
    System.out.println(numlist);
}

}

Answer 1

You calling readObject inside the while statement and inside the while block, making it reading twice.

Also, don't compare Strings with == use equals instead, since the result returns false your while loop will try to read more after closed resultion on EOFException.

Use the variable 'test' you already readed once

while(!(test = (String) ois.readObject()).equals("End")) {
    System.out.println(test);
    Object n1 = test;