Swing/DifferentCellHeight のバックアップ(No.18)

class TextAreaRenderer<E extends String> extends JTextArea
                                         implements ListCellRenderer<E> {
  private static final Color EVEN_COLOR = new Color(230, 255, 230);
  private Border noFocusBorder;
  private Border focusBorder;
  @Override public Component getListCellRendererComponent(
      JList<? extends E> list, E value, int index,
      boolean isSelected, boolean cellHasFocus) {
    // setLineWrap(true);
    setText(Objects.toString(value, ""));
    if (isSelected) {
      // Nimbus
      setBackground(new Color(list.getSelectionBackground().getRGB()));
      setForeground(list.getSelectionForeground());
    } else {
      setBackground(index % 2 == 0 ? EVEN_COLOR : list.getBackground());
      setForeground(list.getForeground());
    }
    if (cellHasFocus) {
      setBorder(focusBorder);
    } else {
      setBorder(noFocusBorder);
    }
    return this;
  }
  @Override public void updateUI() {
    super.updateUI();
    focusBorder = UIManager.getBorder("List.focusCellHighlightBorder");
    noFocusBorder = UIManager.getBorder("List.noFocusBorder");
    if (Objects.isNull(noFocusBorder) && Objects.nonNull(focusBorder)) {
      Insets i = focusBorder.getBorderInsets(this);
      noFocusBorder = BorderFactory.createEmptyBorder(
          i.top, i.left, i.bottom, i.right);
    }
  }
}

private DefaultListModel makeList() {
  DefaultListModel model = new DefaultListModel();
  model.addElement("一行");
  model.addElement("一行目\n二行目");
  model.addElement("一行目\n二行目\n三行目");
  model.addElement("四行\n以上ある\nテキスト\nの場合");
  return model;
}