Swing/ColorComboBox のバックアップの現在との差分(No.24)

class AlternateRowColorComboBox<E> extends JComboBox<E> {
  private static final Color EVEN_BGCOLOR = new Color(225, 255, 225);
  private static final Color ODD_BGCOLOR  = new Color(255, 255, 255);
  private static final Color EVEN_BGC = new Color(0xE1_FF_E1);
  private static final Color ODD_BGC = Color.WHITE;
  private transient ItemListener itemColorListener;

  public AlternateRowColorComboBox() {
    super();
  protected AlternateRowColorComboBox(ComboBoxModel<E> model) {
    super(model);
  }
  public AlternateRowColorComboBox(ComboBoxModel<E> aModel) {
    super(aModel);
  }
  public AlternateRowColorComboBox(E[] items) {
    super(items);
  }
  @Override public void setEditable(boolean aFlag) {
    super.setEditable(aFlag);
    if (aFlag) {
      JTextField field = (JTextField) getEditor().getEditorComponent();
      field.setOpaque(true);
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  @Override public void setEditable(boolean flag) {
    super.setEditable(flag);
    Component field = getEditor().getEditorComponent();
    if (flag && field instanceof JComponent) {
      ((JComponent) field).setOpaque(true);
      field.setBackground(getAlternateRowColor(getSelectedIndex()));
    }
  }
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  @Override public void updateUI() {
    removeItemListener(itemColorListener);
    super.updateUI();
    setRenderer(new DefaultListCellRenderer() {
      @Override public Component getListCellRendererComponent(
          JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
        JLabel c = (JLabel) super.getListCellRendererComponent(
            list, value, index, isSelected, cellHasFocus);
        c.setOpaque(true);
        if (!isSelected) {
          c.setBackground(getAlternateRowColor(index));
        }
        return c;
    ListCellRenderer<? super E> r = getRenderer();
    setRenderer((list, value, index, isSelected, cellHasFocus) -> {
      Component c = r.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
      if (index >= 0 && c instanceof JComponent) {
        ((JComponent) c).setOpaque(true);
      }
      if (!isSelected) {
        c.setBackground(getAlternateRowColor(index));
      }
      return c;
    });
    if (itemColorListener == null) {
      itemColorListener = new ItemListener() {
        @Override public void itemStateChanged(ItemEvent e) {
          if (e.getStateChange() != ItemEvent.SELECTED) {
            return;
          }
          JComboBox cb = (JComboBox) e.getItemSelectable();
          Color rc = getAlternateRowColor(cb.getSelectedIndex());
          if (cb.isEditable()) {
            JTextField field = (JTextField) cb.getEditor().getEditorComponent();
            field.setBackground(rc);
          } else {
            cb.setBackground(rc);
          }
        }
      };
    }
    itemColorListener = e -> {
      if (e.getStateChange() != ItemEvent.SELECTED) {
        return;
      }
      JComboBox<?> cb = (JComboBox<?>) e.getItemSelectable();
      Color rc = getAlternateRowColor(cb.getSelectedIndex());
      if (cb.isEditable()) {
        cb.getEditor().getEditorComponent().setBackground(rc);
      } else {
        cb.setBackground(rc);
      }
    };
    addItemListener(itemColorListener);
    JTextField field = (JTextField) getEditor().getEditorComponent();
    if (field != null) {
      field.setOpaque(true);
      field.setBackground(getAlternateRowColor(getSelectedIndex()));
    }
    EventQueue.invokeLater(() -> {
      Component c = getEditor().getEditorComponent();
      c.setBackground(getAlternateRowColor(getSelectedIndex()));
      if (c instanceof JComponent) {
        ((JComponent) c).setOpaque(true);
      }
    });
  }
  private static Color getAlternateRowColor(int index) {
    return (index % 2 == 0) ? EVEN_BGCOLOR : ODD_BGCOLOR;
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  protected static Color getAlternateRowColor(int index) {
    return index % 2 == 0 ? EVEN_BGC : ODD_BGC;
  }
}