CODEWITHSUNDEEP
javaswingmouseeventjlist
robe0709
robe0709

Reputation: 5

JList value changes when clicked

New to the forum and to Java. I am trying to have my JList respond when double-clicked, which I have accomplished. The JList is being populated by a SQL query which is ran when a button in the GUI is pressed. Based on the SQL query, the JList is populated, this is also working.

The issue comes about if I try to update the JList by clicking the button to query SQL again. When I click that, the change initially shows up in the JList, however when I click on that option in the JList it immediately switches back to what it was initially. When I double-click on what appears to be the incorrect name, the value that I have printing in the console reports correctly. So it has the value correct in the console but the rendering in the JList is not correct.

I appreciate any responses, I have combed the forums without any luck. I am new to Java so I'm sure there is quite a bit that isn't perfect with my code. Code is below please let me know if you need more. Thank you.

 public JPanel results(StringBuilder message)
{   
    StringBuilder[] options = {message};
    showOption = new JList(options);
    showOption.setLocation(300, 50);
    showOption.setSize(140,100);
    showOption.setVisibleRowCount(10);
    textPanel.add(showOption);
    showOption.revalidate();
    showOption.repaint();

    MouseListener mouseListener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
    //JList showOption = (JList) mouseEvent.getSource();

    if (e.getClickCount() == 2) {

    int index = showOption.locationToIndex(e.getPoint());
    Object o = showOption.getModel().getElementAt(index);
    System.out.println("Double-clicked on: " + o.toString());
    }
    }
    };

    showOption.addMouseListener(mouseListener);
    return totalGUI;
}
public static void main ( String args[] )
{
    //JFrame.setDefaultLookAndFeelDecorated(true);
    JFrame frame = new JFrame("[=] JTextField of Dreams [=]");

    GUI_TextField demo = new GUI_TextField();
    frame.setContentPane(demo.createContentPane());
    //frame.setContentPane(demo.results(message));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(510, 400);
    frame.setVisible(true);
}

Upvotes: 0

Views: 754

Answers (1)

MadProgrammer
MadProgrammer

Reputation: 347332

Three things jump out at me immediately.

  1. You're creating a new JList each time
  2. You're manually setting the size and position of the JList
  3. You're not removing the previous JList

For example...

public JPanel results(StringBuilder message)
{   
    StringBuilder[] options = {message};
    // Create new JList
    showOption = new JList(options);
    // This is ill advised
    showOption.setLocation(300, 50);
    showOption.setSize(140,100);
    showOption.setVisibleRowCount(10);
    // What about the last JList?
    textPanel.add(showOption);

This raises a number of possibilities, the likely one is that you are covering over the previous list, which is being brought to the front when textPanel is validated and painted.

Swing follows (loosly) the MVC paradigm (and for more details)

So instead of re-creating the view each time, you should simply re-create the model, for example...

 public JPanel results(StringBuilder message)
 {   
     DefaultListModel model = new DefaultListModel();
     model.addElement(message);
     showOption.setModel(model);

If showOption isn't created initially before this method is called, you should consider putting in a if statement to detect when showOption is null and initialise it appropriately.

You should also avoid using setLocation and setSize. Swing has being designed to operate with the use of layout managers, these make it possible to define workflow and general layout that can be used across multiple platforms.

Take a look at How to use lists and Laying Out Components Within a Container

Upvotes: 3

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