While loop doesn't break after reading multiple line of text with BufferedReader in Java Socket

Question

I have trying to send multiple lines of code from a client to the server.

Here is the code on the server side

            in = new BufferedReader(new InputStreamReader(client.getInputStream()));
            out = new PrintWriter(client.getOutputStream(), true);

            //read client input
            //multi line 
            //https://stackoverflow.com/questions/43416889/java-filereader-only-seems-to-be-reading-the-first-line-of-text-document?newreg=2f77b35c458846dbb1290afce8853930
            String line = "";
            while((line =in.readLine()) != null) {
                System.out.println(line);
            }
            System.out.println("is it here?");

Here is the code on the client side :

    BufferedReader input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(socket.getOutputStream(),true);

    while (true) {
        System.out.print("> ");

        //content server input command (put, lamport clock, message)
        String command = keyboard.readLine();
        if (command.equals("quit")){
            break;
        }
        //read from CSDB/txt1.txt
        String message = readFileReturnString("CSDB/txt1.txt", StandardCharsets.UTF_8);
        System.out.println(message);
        //send to clientHandler through PrintWriter
        out.println(command + " 3 \n" + message);

        //receive response from ClientHandler (lamport clock)
        String serverResponse = input.readLine();
        System.out.println(serverResponse + socket);
    }

Server side is able to print out all the text that is sent from the client side. However, the while loop doesn't break and System.out.println("is it here?"); has never been executed.

May I know why and how I can solve this problem please?

But I would like to reuse this socket. As I may send the message from client to server more than once. — Cecil
– Cecil, Commented Oct 1, 2022 at 8:21
Then you need to tell server when it should exit the loop. Yo may send special string or something. — talex
– talex, Commented Oct 1, 2022 at 8:22

Michael Katt · Accepted Answer · 2022-10-01 09:51:47Z

1

Your Client is waiting for some response of the Server. But the Server does not send any response. The Server writes to the System.out only. The Server has to write the response with the out.

        in = new BufferedReader(new InputStreamReader(client.getInputStream()));
        out = new PrintWriter(client.getOutputStream(), true);

        //read client input
        //multi line 
        //https://stackoverflow.com/questions/43416889/java-filereader-only-seems-to-be-reading-the-first-line-of-text-document?newreg=2f77b35c458846dbb1290afce8853930
        String line = "";
        while((line =in.readLine()) != null) {
            System.out.println(line);
            out.println(line);  // send Server response
        }
        System.out.println("is it here?");

answered Oct 1, 2022 at 9:51

Michael Katt

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Cecil · Accepted Answer · 2022-10-06 03:45:38Z

1

@ talex Then you need to tell server when it should exit the loop. Yo may send special string or something.

This works fine.

        String line = "";
        while((line =in.readLine()) != null) {
            System.out.println(line);
            if (line.equals("break") {
            break;
            }
        }

answered Oct 6, 2022 at 3:45

Cecil

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