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Thread: Simple TCP utility failing right out the gate

  1. #1
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    Default Simple TCP utility failing right out the gate

    I'm trying to set up TCP communications between two machines, but for now (in the initial/testing phase) am using localhost.

    Can anybody see why I'm getting these msgs in the Console (all I'm doing is running the app, not even pressing the button:

    java.net.ConnectException: Connection refused: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(Unknown Source)
    at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at com.jcp.tds.RTTCPSortSimMain.setUpNetworking(RTTCP SortSimMain.java:104)
    at com.jcp.tds.RTTCPSortSimMain.go(RTTCPSortSimMain.j ava:91)
    at com.jcp.tds.RTTCPSortSimMain.main(RTTCPSortSimMain .java:34)
    Exception in thread "Thread-2" java.lang.NullPointerException
    at com.jcp.tds.RTTCPSortSimMain$IncomingReader.run(RT TCPSortSimMain.java:138)
    at java.lang.Thread.run(Unknown Source)

    with the following code (which is basically ripped straight from "Head First Java"):
    public class RTTCPSortSimMain {
     
    ...
        BufferedReader reader;
        PrintWriter writer;
        Socket sock;
     
    	public static void main(String[] args) {
    		new RTTCPSortSimMain().go();
    	}
     
    	public void go() {
    ... (GUI code)       
            JButton sendButton = new JButton("Send and Receive");
            sendButton.addActionListener(new SendButtonListener());
     
            tfHost = new JTextField(16); 
            tfHost.setText("127.0.0.1");
            tfPort = new JTextField(4);
            tfPort.setText("4211"); 
     
    ... (more GUI code)
     
            setUpNetworking();
     
            Thread readerThread = new Thread(new IncomingReader());
            readerThread.start();
     
    ... (more GUI code)
     
        }
     
            private void setUpNetworking() {
            try {
                // for testing (localhost)
     	sock = new Socket("127.0.0.1", 5000);
                InputStreamReader streamReader = new InputStreamReader(sock.getInputStream());
                reader = new BufferedReader(streamReader);
                writer = new PrintWriter(sock.getOutputStream());
                System.out.println("networking established");
            }
            catch(IOException ex)
            {
                ex.printStackTrace();
            }
        }
     
            public class SendButtonListener implements ActionListener {
            @Override
    		public void actionPerformed(ActionEvent ev) {
                try {
                    writer.println(outgoing.getText());
                    writer.flush();
     
                }
                catch (Exception ex) {
                    ex.printStackTrace();
                }
                outgoing.setText("");
                outgoing.requestFocus();
            }
        }
     
            class IncomingReader implements Runnable {
            @Override
    		public void run() {
                String message;
                try {
                    while ((message = reader.readLine()) != null) {
                        System.out.println("client read " + message);
                        incoming.append(message + "\n");
                    }
                } catch (IOException ex)
                {
                    ex.printStackTrace();
                }
            }
        }
     
    }
    ?


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Simple TCP utility failing right out the gate

    This thread has been cross posted here:

    http://www.java-forums.org/networking/46210-simple-tcp-utility-failing-right-out-gate.html#post220720

    Although cross posting is allowed, for everyone's benefit, please read:

    Java Programming Forums Cross Posting Rules

    The Problems With Cross Posting

    When posting on > 1 forum, please provide links to the other forums.


  3. #3
    mmm.. coffee JavaPF's Avatar
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    Default Re: Simple TCP utility failing right out the gate

    Was this solved on the other forum?
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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