How to add a CheckBox into an item within a ListBox?

[KenSyd]

Hi all,

I need to add a CheckBox into the items of a list box to indicate this item has been selected, but I can't find the right way to do so. I will appreciate it if somebody can help me to resolve this problem. Thanks a lot.

Regards,
Ken

[sjalle]

..like this. Just remember that a JCheckBox renderer is only a JCheckBox by its looks, e.g. it will not get selected/unselected when you click it in the list. To do that you would have to implement a mouse listener for your list and process the list clicked list element (set it selected/unselected).

So, don't mix up the list element's isSelected and the JCheckBox's isSelected() ...

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

/**
* Using ListCellRenderer
**/
public class CheckList extends JFrame implements ListCellRenderer, ActionListener {
  private Color stdColor=null;
  BorderLayout borderLayout1 = new BorderLayout();
  JScrollPane jScrollPane1 = new JScrollPane();
  JList theList = new JList();
  JPanel jPanel1 = new JPanel();
  JButton addOnBtn = new JButton();
  JButton addOffBtn = new JButton();

  public CheckList() {
    setBounds(10,10,170,270);
    try {
      jbInit();
      stdColor=getBackground();
      addOnBtn.addActionListener(this);
      addOffBtn.addActionListener(this);
      theList.setCellRenderer(this); // <---
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    CheckList radioList = new CheckList();
    radioList.setVisible(true);
  }
  /**
  * The ListCellRenderer interface implementation method
  */
  public Component getListCellRendererComponent(JList list,
                                                Object value,
                                                int index,
                                                boolean isSelected,
                                                boolean cellHasFocus) {

    JCheckBox aCB=(JCheckBox)value;
    if (isSelected) {
      aCB.setBackground(Color.red);
    } else {
      aCB.setBackground(stdColor);
    }

    return aCB;

  }
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(borderLayout1);
    addOnBtn.setBounds(new Rectangle(20, 7, 60, 21));
    addOnBtn.setPreferredSize(new Dimension(60, 22));
    addOnBtn.setText("On");
    jPanel1.setLayout(null);
    jPanel1.setMinimumSize(new Dimension(1, 1));
    jPanel1.setPreferredSize(new Dimension(1, 32));
    addOffBtn.setBounds(new Rectangle(89, 7, 60, 21));
    addOffBtn.setText("Off");
    this.getContentPane().add(jScrollPane1, BorderLayout.CENTER);
    this.getContentPane().add(jPanel1, BorderLayout.SOUTH);
    jPanel1.add(addOnBtn, null);
    jPanel1.add(addOffBtn, null);
    jScrollPane1.getViewport().add(theList, null);
  }
  private void addToList(Object ob) {
    Vector v=new Vector();
    for (int i=0; i<theList.getModel().getSize(); i++) {
      v.addElement(theList.getModel().getElementAt(i));
    }
    v.addElement(ob);
    theList.setListData(v);
  }
  public void actionPerformed(ActionEvent e) {
    JCheckBox cb=null;
    if (e.getSource()==addOnBtn) {
      cb=new JCheckBox("I'm ON",true);

    } else {
      cb=new JCheckBox("I'm OFF",false);
    }
    addToList(cb);
  }
}

[KenSyd]

That is very helpful reply, thanks a lot.

[runescience]

I had the same problem. I fixed it thanks to your code, but now again, I have another problem. I want the user to be able to check the box on and off in the list box. How do I do that, or rather, can it be done???