Tri-state check boxes

Question

I have a requirement to create tri-state check boxes. The check-box is supposed to show an aggregate value from multiple sources, so it may show "entirely on", "entirely off" or "mixed". The appearance for "mixed" (as seen in many word-processors when formatting large section of text, or when installing only some sub-components of a component of Windows,) should be a check on a gray background.
Currently my best effort has been to create a JPanel containing two JCheckBox objects stacked with an OverlayLayout. One has no text and is transparent to the mouse, it is just the check part. The other is partically obscured by the first, but provides the label and response to clicks. The latter updates the former with its state, but the former may be set to "mixed", which is simulated by disabling it.
This is a very ugly way of acheiving what I want. It does give consistently correct results across PLAFs, but it has a tendency to flicker because the functional JCheckBox doesn't like being obscured. It also doesn't show shading in the box while the mouse button is held down over it, because this occurs in the obscured component, not the puppet component shown. Is there an existing component with the functionality I desire? Alternatively is there some way to create a new component without having to extend every PLAF that I want to use with it? Trying to figure out how to add new components in the same look and feel is quite intimidating.
Many thanks,
Andrew Wilson.

Answer 1

The Follwoing code will work out for you i have read in an article
import javax.swing.*;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ActionMapUIResource;
import java.awt.event.*;
* Maintenance tip - There were some tricks to getting this code
* working:
* 1. You have to overwite addMouseListener() to do nothing
* 2. You have to add a mouse event on mousePressed by calling
* super.addMouseListener()
* 3. You have to replace the UIActionMap for the keyboard event
* "pressed" with your own one.
* 4. You have to remove the UIActionMap for the keyboard event
* "released".
* 5. You have to grab focus when the next state is entered,
* otherwise clicking on the component won't get the focus.
* 6. You have to make a TristateDecorator as a button model that
* wraps the original button model and does state management.
public class TristateCheckBox extends JCheckBox {
/** This is a type-safe enumerated type */
public static class State { private State() { } }
public static final State NOT_SELECTED = new State();
public static final State SELECTED = new State();
public static final State DONT_CARE = new State();
private final TristateDecorator model;
public TristateCheckBox(String text, Icon icon, State initial){
super(text, icon);
// Add a listener for when the mouse is pressed
super.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
grabFocus();
model.nextState();
// Reset the keyboard action map
ActionMap map = new ActionMapUIResource();
map.put("pressed", new AbstractAction() {
public void actionPerformed(ActionEvent e) {
grabFocus();
model.nextState();
map.put("released", null);
SwingUtilities.replaceUIActionMap(this, map);
// set the model to the adapted model
model = new TristateDecorator(getModel());
setModel(model);
setState(initial);
public TristateCheckBox(String text, State initial) {
this(text, null, initial);
public TristateCheckBox(String text) {
this(text, DONT_CARE);
public TristateCheckBox() {
this(null);
/** No one may add mouse listeners, not even Swing! */
public void addMouseListener(MouseListener l) { }
* Set the new state to either SELECTED, NOT_SELECTED or
* DONT_CARE. If state == null, it is treated as DONT_CARE.
public void setState(State state) { model.setState(state); }
/** Return the current state, which is determined by the
* selection status of the model. */
public State getState() { return model.getState(); }
* Exactly which Design Pattern is this? Is it an Adapter,
* a Proxy or a Decorator? In this case, my vote lies with the
* Decorator, because we are extending functionality and
* "decorating" the original model with a more powerful model.
private class TristateDecorator implements ButtonModel {
private final ButtonModel other;
private TristateDecorator(ButtonModel other) {
this.other = other;
private void setState(State state) {
if (state == NOT_SELECTED) {
other.setArmed(false);
setPressed(false);
setSelected(false);
} else if (state == SELECTED) {
other.setArmed(false);
setPressed(false);
setSelected(true);
} else { // either "null" or DONT_CARE
other.setArmed(true);
setPressed(true);
setSelected(true);
* The current state is embedded in the selection / armed
* state of the model.
* We return the SELECTED state when the checkbox is selected
* but not armed, DONT_CARE state when the checkbox is
* selected and armed (grey) and NOT_SELECTED when the
* checkbox is deselected.
private State getState() {
if (isSelected() && !isArmed()) {
// normal black tick
return SELECTED;
} else if (isSelected() && isArmed()) {
// don't care grey tick
return DONT_CARE;
} else {
// normal deselected
return NOT_SELECTED;
/** We rotate between NOT_SELECTED, SELECTED and DONT_CARE.*/
private void nextState() {
State current = getState();
if (current == NOT_SELECTED) {
setState(SELECTED);
} else if (current == SELECTED) {
setState(DONT_CARE);
} else if (current == DONT_CARE) {
setState(NOT_SELECTED);
/** Filter: No one may change the armed status except us. */
public void setArmed(boolean b) {
/** We disable focusing on the component when it is not
* enabled. */
public void setEnabled(boolean b) {
setFocusable(b);
other.setEnabled(b);
/** All these methods simply delegate to the "other" model
* that is being decorated. */
public boolean isArmed() { return other.isArmed(); }
public boolean isSelected() { return other.isSelected(); }
public boolean isEnabled() { return other.isEnabled(); }
public boolean isPressed() { return other.isPressed(); }
public boolean isRollover() { return other.isRollover(); }
public void setSelected(boolean b) { other.setSelected(b); }
public void setPressed(boolean b) { other.setPressed(b); }
public void setRollover(boolean b) { other.setRollover(b); }
public void setMnemonic(int key) { other.setMnemonic(key); }
public int getMnemonic() { return other.getMnemonic(); }
public void setActionCommand(String s) {
other.setActionCommand(s);
public String getActionCommand() {
return other.getActionCommand();
public void setGroup(ButtonGroup group) {
other.setGroup(group);
public void addActionListener(ActionListener l) {
other.addActionListener(l);
public void removeActionListener(ActionListener l) {
other.removeActionListener(l);
public void addItemListener(ItemListener l) {
other.addItemListener(l);
public void removeItemListener(ItemListener l) {
other.removeItemListener(l);
public void addChangeListener(ChangeListener l) {
other.addChangeListener(l);
public void removeChangeListener(ChangeListener l) {
other.removeChangeListener(l);
public Object[] getSelectedObjects() {
return other.getSelectedObjects();
then compile this code
in another class file
import javax.swing.*;
import java.awt.*;
public class TristateCheckBoxTest {
public static void main(String args[]) throws Exception {
JFrame frame = new JFrame("TristateCheckBoxTest");
frame.getContentPane().setLayout(new GridLayout(0, 1, 5, 5));
final TristateCheckBox swingBox = new TristateCheckBox(
"Testing the tristate checkbox");
swingBox.setMnemonic('T');
frame.getContentPane().add(swingBox);
frame.getContentPane().add(new JCheckBox(
"The normal checkbox"));
UIManager.setLookAndFeel(
UIManager.getSystemLookAndFeelClassName());
final TristateCheckBox winBox = new TristateCheckBox(
"Testing the tristate checkbox",
TristateCheckBox.SELECTED);
frame.getContentPane().add(winBox);
final JCheckBox winNormal = new JCheckBox(
"The normal checkbox");
frame.getContentPane().add(winNormal);
// wait for 3 seconds, then enable all check boxes
new Thread() { {start();}
public void run() {
try {
winBox.setEnabled(false);
winNormal.setEnabled(false);
Thread.sleep(3000);
winBox.setEnabled(true);
winNormal.setEnabled(true);
} catch (InterruptedException ex) { }
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.show();
this will give you all the check boxes...
All The Best