\npublic class ThreeStateCheckBox extends JCheckBox\n{\n\n  static ButtonModel thirdStateModel = new AlwaysPressedSelectedArmedModel();\n\n  ThreeStateCheckBox(String text) {\n    super(text);    \n    setModel(new ThreeStateButtonModel());\n  }\n\n  protected void paintComponent(Graphics g) {\n    ThreeStateButtonModel model = (ThreeStateButtonModel)getModel();\n      \n    if (model.getThirdState() && model.isEnabled()) {\n      // in this state, we want the checkbox to be painted selected,\n      // pressed an armed. So, we substitute our real model with a\n      // fake one that returns selected, pressed and armed no matter\n      // what. Then, after the painting is done, we restore the original model.\n      \n      // this relies on the single-threaded nature of Swing - no other\n      // events will be processed while we're painting. We will have\n      // to change the code if mouse clicks will start happening in\n      // parallel with painting\n\n      // we have to access "model" directly, because setModel() causes\n      // a reppint, among other things\n\n      this.model = thirdStateModel;\n      super.paintComponent(g);\n      this.model = model;\n\n      // back to the originally scheduled programming\n\n    } else {\n      super.paintComponent(g);      \n    }\n  }\n\n  void setThirdState() {\n    ((ThreeStateButtonModel)getModel()).setThirdState();\n  }\n\n  boolean getThirdState() {\n    return ((ThreeStateButtonModel)getModel()).getThirdState();\n  }\n\n  /// The model that cause the checkbox to paint itself in the right\n  /// way in the third state\n  static public class AlwaysPressedSelectedArmedModel extends DefaultButtonModel {\n    public boolean isPressed() {\n      return true;\n    }\n\n    public boolean isArmed() {\n      return true;\n    }\n    \n    public boolean isSelected() {\n      return true;\n    }\n\n  }\n\n<model code here>\n\n}\n\n