Code
class CheckedComboBox<E extends CheckableItem> extends JComboBox<E> {
private boolean keepOpen;
private transient ActionListener listener;
protected CheckedComboBox() {
super();
}
protected CheckedComboBox(ComboBoxModel<E> aModel) {
super(aModel);
}
protected CheckedComboBox(E[] m) {
super(m);
}
@Override public Dimension getPreferredSize() {
return new Dimension(200, 20);
}
@Override public void updateUI() {
setRenderer(null);
removeActionListener(listener);
super.updateUI();
listener = e -> {
if ((e.getModifiers() & InputEvent.MOUSE_EVENT_MASK) != 0) {
updateItem(getSelectedIndex());
keepOpen = true;
}
};
setRenderer(new CheckBoxCellRenderer<CheckableItem>());
addActionListener(listener);
getInputMap(JComponent.WHEN_FOCUSED).put(
KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0), "checkbox-select");
getActionMap().put("checkbox-select", new AbstractAction() {
@Override public void actionPerformed(ActionEvent e) {
Accessible a = getAccessibleContext().getAccessibleChild(0);
if (a instanceof BasicComboPopup) {
BasicComboPopup pop = (BasicComboPopup) a;
updateItem(pop.getList().getSelectedIndex());
}
}
});
}
private void updateItem(int index) {
if (isPopupVisible()) {
E item = getItemAt(index);
item.selected ^= true;
removeItemAt(index);
insertItemAt(item, index);
setSelectedItem(item);
}
}
@Override public void setPopupVisible(boolean v) {
if (keepOpen) {
keepOpen = false;
} else {
super.setPopupVisible(v);
}
}
}
References
