JTableのセルエディタとして編集追加可能なJComboBoxを使用する

class ComboCellEditor extends AbstractCellEditor implements TableCellEditor {
  private final JComboBox<String> combo = new JComboBox<>();

  protected ComboCellEditor() {
    super();
    combo.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
    combo.setEditable(true);
    combo.addActionListener(e -> fireEditingStopped());
  }

  @Override public Component getTableCellEditorComponent(
      JTable table, Object value, boolean isSelected, int row, int column) {
    if (value instanceof ComboBoxModel) {
      @SuppressWarnings("unchecked")
      ComboBoxModel<String> m = (ComboBoxModel<String>) value;
      combo.setModel(m);
    }
    return combo;
  }

  @Override public Object getCellEditorValue() {
    DefaultComboBoxModel<String> m = (DefaultComboBoxModel<String>) combo.getModel();
    if (combo.isEditable()) {
      String str = Objects.toString(combo.getEditor().getItem(), "");
      if (!str.isEmpty() && m.getIndexOf(str) < 0) {
        m.insertElementAt(str, 0);
        combo.setSelectedIndex(0);
      }
    }
    return m;
  }
}