RadioGroup()
向对话框视图添加单选组,每个子视图包含单选按钮
RadioGroup():add()
向组中添加单选按钮
RadioGroup():getButtons()
返回单选按钮列表
RadioGroup():getId()
返回视图 id
RadioGroup():showAsDropdown()
Shows the options as a dropdown instead of round buttons. Better for long lists. The answer is still the id of the chosen RadioButton.