code: protected void selectItem(Object item)
      {
          if (this.selectionListLabelMessages != null && this.selectionListLabelMessages.length > 0)
          {
              int itemIndex = search(this.selectionListKeys, item);
              if (itemIndex > -1) // item found in list (may/can be null)
              {
                  settingValueModel = true;
                  this.combobox.setSelectedItem(this.selectionListLabelMessages[itemIndex]);
                  settingValueModel = false;
              }
              else
              // newValue not in list, select defaultIndex or nothing
              {
                  this.combobox.setSelectedIndex(getDefaultKeyIndex());
              }
          }
      }
docs: Selects the given item in the current selectionList of the comboBoxModel.
  When the item doesn't map to an entry in the comboBoxModel, select a
  default one. See {@link #getDefaultKeyIndex()} and
  {@link #setDefaultKeyIndex(int)} for default.
  
  @param item
  object that needs to be selected in the comboBox.