Trying to make a DatagramSocket UDP server/client chat app but having some problems getting the GUI to update after receiving a packet with a DatagramPacket. Here's my code; the only thing I left out, which I thought was irrelevant, was my grouplayout code for my JFrame window.
public class Server extends JFrame {
JButton startServerButton;
JTextField textField;
JTextArea textArea;
public Server() {
super("Server");
initComponents();
setResizable(false);
setVisible(true);
}
private void startServer() throws IOException {
DatagramSocket serverSocket;
String sentence;
startServerButton.setText("Server started");
startServerButton.setEnabled(false);
while (true) {
serverSocket = new DatagramSocket(9876);
// receive
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
sentence = new String(receivePacket.getData());
int port = receivePacket.getPort();
System.out.println("RECEIVED (port " + port + "): " + sentence);
showMessage("RECEIVED (port " + port + "): " + sentence);
InetAddress IPAddress = receivePacket.getAddress();
// send
byte[] sendData = sentence.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
serverSocket.send(sendPacket);
serverSocket.close();
}
}
private void showMessage(final String text) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
textArea.append("\n" + text);
}
});
}
private void initComponents() {
startServerButton = new JButton();
textField = new JTextField();
textArea = new JTextArea();
textArea.setEditable(false);
startServerButton.setText("Start server");
startServerButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
try {
startServer();
} catch (IOException e) {
e.printStackTrace();
}
}
});
...grouplayout stuff here...
}
public static void main(String args[]) {
Server server = new Server();
}
}
So the problem is, the textArea on my JFrame never gets updated, but my System.out.println() always prints correctly the message received from my Client class. I can show the code for my Client class but I felt it was irrelevant. I would appreciate any help, thanks.
You must start your socket listener in another Thread. Otherwise you block the repainting.
Something like this:
startServerButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
Thread t = new Thread(new Runnable() {
public void run() {
try {
startServer();
} catch (IOException e) {
e.printStackTrace();
}
}
});
t.start();
}
});