尝试从JTextArea回显文本

Question

I can't really see where the mistakes are with this.

I've set up a KeyListener for the textAreaTop component, so every time a key is pressed, a string is sent to the server, which echoes it back to the teaxtAreaBottom component. I'm aware stdIn is not being used yet.

When the first key is pressed, a connection is made, but when the second key is pressed I get the following error: Couldn't get I/O for the connection to localhost. Also, nothing is appended to the textAreaBottom component.

//Client

    @Override
    public void keyPressed(KeyEvent e) {
    String hostName = "localhost";
     int portNumber = 4000;

    try (Socket echoSocket = new Socket(hostName, portNumber);
         PrintWriter out = new PrintWriter(echoSocket.getOutputStream(),
                    true);
         BufferedReader in = new BufferedReader(new InputStreamReader(
                    echoSocket.getInputStream()));
         BufferedReader stdIn = new BufferedReader(
                    new InputStreamReader(System.in))) {

        String userInput = textAreaTop.getText();
        out.println(userInput);
        textAreaBottom.setText(null);
        textAreaBottom.setText(in.readLine());

    } catch (UnknownHostException ex) {
         System.err.println("Don't know about host " + hostName);
        System.exit(1);
    } catch (IOException ex) {
        System.err.println("Couldn't get I/O for the connection to "
                + hostName);
        System.exit(1);
    }
    }

// Server

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

    int portNumber = 4000;

    try {
        ServerSocket serverSocket = new ServerSocket(portNumber);
        Socket clientSocket = serverSocket.accept();
        System.out.println("connection accepted");
        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),
                true);
        BufferedReader in = new BufferedReader(new InputStreamReader(
                clientSocket.getInputStream()));
        {
            String inputLine;
            while ((inputLine = in.readLine()) != null) {
                out.println(inputLine);
            }
        }
    } catch (IOException e) {
        System.out
                .println("Exception caught when trying to listen on port "
                        + portNumber + " or listening for a connection");
        System.out.println(e.getMessage());
    }
}

Any advice would be much appreciated.

Thanks

Answer 1

The problem is because of two little flaws:

1. You should implement keyReleased() instead of keyPressed() , because the text in the textAreaTop is being updated after keyPressed() being called. So when the keyReleased() method is being called your textAreaTop has the latest text you have input.

2. You shouldn't create that Socket object everytime you press a key. You should define that Socket and the references to the input/output Streams outside of the keyReleased (former keyPressed) anonymous class and method. So every time you press a key the only job to do is to get the text from textAreaTop and out.println(text) to the server. In this case I have tested the code and it's working properly.

Good Luck.