JButton in JList cell is not clickable

Question

In my current swing project I have a JList displaying all active sockets, and each cell has a JButton to close that socket. But the JButton in the cell is not clickable: listener does not get fired.

I have modified the code to minimal as follows.

private class ConnectionListRenderer extends JButton implements ListCellRenderer {

    public Component getListCellRendererComponent(JList jlist, Object o, int i, boolean bln, boolean bln1) {

        addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                //do something (close the socket in my project)
            }
        });
        return this;
    }
}


jList.setCellRenderer(new ConnectionListRenderer());

The list looks fine, but the button on in is not clickable. Am I wrong or JList just does not support JButton in the getting fired?

Answer 1

Here's an example that seems to work, although you don't get the same visual effect of a normal button click. Perhaps someone with better painting skill than me could improve this to simulate the visual pressed button effect.

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

/**
 * A JList of JButtons.
 */
public class JButtonListDemo implements Runnable
{
  private JList jlist;

  public static void main(String args[])
  {
    SwingUtilities.invokeLater(new JButtonListDemo());
  }

  public void run()
  {
    Object[] items = new ButtonItem[] {
        new ButtonItem("Apple"),
        new ButtonItem("Banana"),
        new ButtonItem("Carrot"),
        new ButtonItem("Date"),
        new ButtonItem("Eggplant"),
        new ButtonItem("Fig"),
        new ButtonItem("Guava"),
    };

    jlist = new JList(items);
    jlist.setCellRenderer(new ButtonListRenderer());
    jlist.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    jlist.setVisibleRowCount(5);
    jlist.addMouseListener(new MouseAdapter()
    {
      @Override
      public void mouseClicked(MouseEvent event)
      {
        clickButtonAt(event.getPoint());
      }
    });

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(new JScrollPane(jlist));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }

  private void clickButtonAt(Point point)
  {
    int index = jlist.locationToIndex(point);
    ButtonItem item = (ButtonItem) jlist.getModel().getElementAt(index);
    item.getButton().doClick();
//    jlist.repaint(jlist.getCellBounds(index, index));
  }

  public class ButtonItem
  {
    private JButton button;

    public ButtonItem(String name)
    {
      this.button = new JButton(name);
      button.addActionListener(new ActionListener()
      {
        @Override
        public void actionPerformed(ActionEvent e)
        {
          System.out.println(button.getText() + " was clicked.");
        }
      });
    }

    public JButton getButton()
    {
      return button;
    }

    @Override
    public String toString()
    {
      return button.getText();
    }
  }

  class ButtonListRenderer extends JButton implements ListCellRenderer
  {
    public Component getListCellRendererComponent(JList comp, Object value, int index,
                                                  boolean isSelected, boolean hasFocus)
    {
      setEnabled(comp.isEnabled());
      setFont(comp.getFont());
      setText(value.toString());

      if (isSelected)
      {
        setBackground(comp.getSelectionBackground());
        setForeground(comp.getSelectionForeground());
      }
      else
      {
        setBackground(comp.getBackground());
        setForeground(comp.getForeground());
      }

      return this;
    }
  }
}

Alternatively, you could always layout your JButtons vertically on a JPanel (using a new GridLayout(0,1) perhaps) and then put your JPanel in a JScrollPane, thus mocking a JList of JButtons.