Java Swing单选按钮

Question

我要将单选按钮列表之一设置为默认或选中；我怎么做？这是我要从列表中选择的部分：

widget_LHSGrid.add(UtlComponent.textGraphic("How was Case Referred?"), UtlComponent.gridBag(0, 0, GridBagConstraints.EAST));
widget_LHSGrid.add(getwidget_NewCase_ReferredHow();