swing 单选框（互斥buttonGroup），设置默认值，获取值

单选框默认为男

this.jrb_man.setSelected(true);

组合框默认第一个
this.jcb_bookType.setSelectedIndex(0);

获取单选框的值
String sex="";
boolean b=true;
if(b==this.jrb_man.isSelected()&&this.jrb_female.isSelected()!=b){
sex="男";
}else if(b==this.jrb_female.isSelected()&&b!=this.jrb_man.isSelected()){
sex="女";
}else if(b==this.jrb_female.isSelected()&&b==this.jrb_man.isSelected()){
JOptionPane.showMessageDialog(null,"只能选择一个性别");
return;
}

------------------------

互斥单选框

buttonGroup1 = new javax.swing.ButtonGroup();
buttonGroup1.add(jrb_crm);
buttonGroup1.add(jrb_cbs);
buttonGroup1.add(jrb_sps);