JList doesn't update contents immediately

Try calling:

IPList.updateUI();


You might also want to do this:

SwingUtilities.invokeLater(new Runnable() {
    public void run() {
        //Put your code which modifies the
        //GUI right here...
    }
}

I've tried the following

1- JList.setModel(new DefaultListModel());

2- DefaultListModel model = Jlist.getModel();

(1) worlks fine but unfortunately (2) doesn't. I'm using JDL1.2. How do I get the DefaultListModel back from my JList after I have set it?

heyhey's answer is definitely the way to go ...

I've solved (2) by casting the ListModel to a DefautListModel.

So now I am using a DefaultListModel for adding entries to my list. But it still doesn't refresh it's contents until my for loop is over ...

try
DefaultListModel model = (DefaultListModel)Jlist.getModel();

model.setElementAt(newData, index)l

heyhey: I guess you just missed my last posting :)

So why is my list still not refreshing itself everytime I changed a list item?

post the whole code (small compilable example that we can test)

Ok. Coming right up.

Here's the main GUI class

import java.util.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Frame1 extends JFrame {

  DefaultListModel listModel = new DefaultListModel();

  TextField ip4 = new TextField();
  TextField ip3 = new TextField();
  TextField ip2 = new TextField();
  TextField ip1 = new TextField();
  JButton addButton = new JButton();
  JButton deleteButton = new JButton();
  JList IPList = new JList();
  JLabel jLabel4 = new JLabel();
  JLabel jLabel3 = new JLabel();
  JLabel jLabel2 = new JLabel();

  JLabel jLabel5 = new JLabel();
  JPanel jPanel1 = new JPanel();
  JButton uploadButton = new JButton();
  JScrollPane jScrollPane1 = new JScrollPane();

  public Frame1() {
    try {
      jbInit();
      this.setBounds(400,400,500,400);
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }

  private void jbInit() throws Exception {
    this.getContentPane().setLayout(new FlowLayout());
    IPList.setModel(listModel);
    addButton.addActionListener(new java.awt.event.ActionListener() {

      public void actionPerformed(ActionEvent e) {
        addButton_actionPerformed(e);
      }
    });
    addButton.setText("Add IP");
    deleteButton.setText("Delete IP");
    deleteButton.addActionListener(new java.awt.event.ActionListener() {

      public void actionPerformed(ActionEvent e) {
        deleteButton_actionPerformed(e);
      }
    });
    deleteButton.setToolTipText("");
    jLabel4.setText(".");
    jLabel3.setText(".");
    jLabel2.setText(".");
    this.addWindowListener(new java.awt.event.WindowAdapter() {

      public void windowClosing(WindowEvent e) {
        this_windowClosing(e);
      }
    });
    this.setResizable(false);
    jLabel5.setText("IP Address to Add:");
    jPanel1.setBorder(BorderFactory.createEtchedBorder());
    uploadButton.setText("Start");
    uploadButton.addActionListener(new java.awt.event.ActionListener() {

      public void actionPerformed(ActionEvent e) {
        uploadButton_actionPerformed(e);
      }
    });
    IPList.setDoubleBuffered(true);
    this.getContentPane().add(jLabel5);
    this.getContentPane().add(jPanel1);
    jPanel1.add(ip1);
    jPanel1.add(jLabel3);
    jPanel1.add(ip2);
    jPanel1.add(jLabel2);
    jPanel1.add(ip4);
    jPanel1.add(jLabel4);
    jPanel1.add(ip3);
    this.getContentPane().add(addButton);
    this.getContentPane().add(uploadButton);
    this.getContentPane().add(deleteButton);
    this.getContentPane().add(jScrollPane1);
    jScrollPane1.getViewport().add(IPList, null);
  }

  void addButton_actionPerformed(ActionEvent e) {

    if ((ip1.getText().equals("")) || (ip2.getText().equals("")) ||
        (ip3.getText().equals("")) || (ip4.getText().equals(""))) {
          return;
    }
    String address = ip1.getText() + "." + ip2.getText() + "." +
                     ip3.getText() + "." + ip4.getText();
    listModel.insertElementAt(address,0);
  }

  public static void main(String[] args) {
    Frame1 f = new Frame1();
    f.setVisible(true);
  }

  void this_windowClosing(WindowEvent e) {
    System.exit(0);
  }

  void deleteButton_actionPerformed(ActionEvent e) {
    if (IPList.isSelectionEmpty()) {return;}
    int selectedIndex = IPList.getSelectedIndex();
    listModel.removeElementAt(selectedIndex);
  }

  void uploadButton_actionPerformed(ActionEvent e) {

    UploadClient uc;
    int numberOfClients = IPList.getModel().getSize();
    String address;
    DefaultListModel model = (DefaultListModel)IPList.getModel();

    for (int i = 0; i < numberOfClients; i++) {
      address = (String)listModel.getElementAt(i);
      try {
        uc = new UploadClient(address, 1500, "c:\\clientDir");
        uc.synchronize();
        model.set(i,new String(address + " uploaded"));
      }
      catch (Exception ex) {
        model.set(i,new String(address + " error"));
        ex.printStackTrace();
      }
    }
  }
}

Here's the other class that is needed

import java.io.*;
import java.net.*;
import java.util.*;

public class UploadClient {

  final boolean debug   = true;
  final int BUFFLEN     = 64 * 1024;
  final String USERNAME = "devi";
  final String PASSWORD = "devi";

  int port;
  Socket soc;
  String ipAdd;
  String syncDir;
  BufferedReader in;
  BufferedOutputStream bos;

  public UploadClient(String ipAdd, int port, String syncDir) {

    this.ipAdd   = ipAdd;
    this.port    = port;
    this.syncDir = syncDir;
  }

  public void synchronize() throws IOException {

    initiateSession();
  }

  public boolean initiateSession() throws IOException {

    soc             = new Socket(ipAdd, port);
    in              = new BufferedReader(new InputStreamReader(soc.getInputStream()));
    OutputStream os = soc.getOutputStream();
    bos             = new BufferedOutputStream(os);

    String serverReply = null;

    serverReply = in.readLine();
    serverReply = in.readLine();
    writeLine(USERNAME);
    serverReply = in.readLine();
    writeLine(PASSWORD);
    serverReply = in.readLine();
    boolean isAuthorized = serverReply.equals("LOGGEDIN");
    if (!isAuthorized) {
      soc.close();
    }
    return isAuthorized;
  }

  public void writeLine(String line) throws IOException {

    byte ln[] = line.getBytes();
    bos.write(ln, 0, ln.length);
    bos.write(13);
    bos.flush();
  }
}

How to use:

- compile and run Frame1.java
- add some ip addresses using the textfields (correctness in ot needed)
- click on add to add an IP to the JList
- after adding a few IPs click on Start
- this will generate a lot of error which will print to the console
- after all ip addresses have been done, each IP address will be appended the String "error"

As you will see all List items get updated/appended at the same time, not one by one ...