class WizardPanel1 implements WizardDescriptor.ValidatingPanel {

    //    public final void addChangeListener(ChangeListener l) {
//    }
//
//    public final void removeChangeListener(ChangeListener l) {
//    }
    private final Set<ChangeListener> listeners = new HashSet<>(1); // or can use ChangeSupport in NB 6.0
    /**
     * The visual component that displays this panel. If you need to access the
     * component from this class, just use getComponent().
     */
    private Component component;

    // Get the visual component for the panel. In this template, the component
    // is kept separate. This can be more efficient: if the wizard is created
    // but never displayed, or not all panels are displayed, it is better to
    // create only those which really need to be visible.
    @Override
    public Component getComponent() {
        if (component == null) {
            component = new WizardVisualPanel1();
            this.addChangeListener((ChangeListener) component);
        }
        return component;
    }

    @Override
    public HelpCtx getHelp() {
        // Show no Help button for this panel:
        return HelpCtx.DEFAULT_HELP;
        // If you have context help:
        // return new HelpCtx(SampleWizardPanel1.class);
    }

    @Override
    public boolean isValid() {<FILL_FUNCTION_BODY>}

    @Override
    public final void addChangeListener(ChangeListener l) {
        synchronized (listeners) {
            listeners.add(l);
        }
    }

    @Override
    public final void removeChangeListener(ChangeListener l) {
        synchronized (listeners) {
            listeners.remove(l);
        }
    }

    protected final void fireChangeEvent() {
        Iterator<ChangeListener> it;
        synchronized (listeners) {
            it = new HashSet<>(listeners).iterator();
        }
        ChangeEvent ev = new ChangeEvent(this);
        while (it.hasNext()) {
            it.next().stateChanged(ev);
        }
    }

    // You can use a settings object to keep track of state. Normally the
    // settings object will be the WizardDescriptor, so you can use
    // WizardDescriptor.getProperty & putProperty to store information entered
    // by the user.
    @Override
    public void readSettings(Object settings) {
    }

    @Override
    public void storeSettings(Object settings) {
    }

    @Override
    public void validate() throws WizardValidationException {
        if (!isValid()) {
            throw new WizardValidationException(null, "Can't be empty.", null);
        }
    }
}

        WizardVisualPanel1 panel = (WizardVisualPanel1) getComponent();
        return !panel.emptyList();
        // If it is always OK to press Next or Finish, then:
// If it depends on some condition (form filled out...), then:
        // return someCondition();
        // and when this condition changes (last form field filled in...) then:
        // fireChangeEvent();
        // and uncomment the complicated stuff below.
    
<no_super_class>