Question

Im using a JPanel with propertyChangeListener and want it to rerender itself based on whenever a particular variable model changes. My code for the same is as follows —

public class LabelMacroEditor extends JPanel implements PropertyChangeListener {

    private static final long serialVersionUID = 1L;
    private LabelMacroModel model;

    public LabelMacroEditor(LabelMacroModel bean) {

        this.model = bean;
        model.addPropertyChangeListener(this);
        setupComponents();
        validate();
        setVisible(true);
    }

    public void setupComponents()
    {

        Box allButtons =  Box.createVerticalBox();
        JScrollPane macroModelScroller =  new JScrollPane(allButtons);
        macroModelScroller.setPreferredSize(new Dimension(300, 200));
        for(MacroModel macroModel : model.getMacroModelList())
        {
            LabelMacroEditorEditableEntity macroEditorEntity =  new LabelMacroEditorEditableEntity(macroModel);
            Box entityBox =  Box.createHorizontalBox();
            entityBox.add(macroEditorEntity.getUpButton());
            entityBox.add(Box.createHorizontalStrut(15));
            entityBox.add(macroEditorEntity.getMacroDetailsButton());
            entityBox.add(Box.createHorizontalStrut(15));
            entityBox.add(macroEditorEntity.getDownButton());

            allButtons.add(entityBox);
        }
        add(macroModelScroller);
    }

    @Override
    public void propertyChange(PropertyChangeEvent arg0) {
        revalidate();
        repaint();
    }
}

When i use the debug mode in eclipse i can see that whenever there is a change to model it triggers off the call propertyChange and it also runs over revalidate and repaint but only the JPanel display remains the same. It does not seem to be rerendering itself.
Anything fundamental that I’m missing here ?

EDIT :

An example snippet of a property im changing is as follows —

labelMacroModel.addMacroModel(addedMacroModel);

where labelMacroModel is of the type LabelMacroModel and addedMacroModel is of the type Macro

Now the relevant part of LabelMacroModel class that fires off the property change is as follows —

private List<MacroModel> macroModelList;// this is the list of all MacroModels
public void addMacroModel(MacroModel macroModel) {
        macroModelList.add(macroModel);

        pcs.fireIndexedPropertyChange("LabelMacroModel", macroModelList.size(), null, macroModel);
    }

Answer 1

Its not clear how you are changing the components in the panel. If panel is not updated then repaint/revalidate will have no effect. I think you should not need revalidate/repaint to be called explicitly if you are not modifying the way components are laid out. JButton.setText should for example change the label of the button without need of calling repaint.