android studio:RadioGroup中不选中RadioButton，Switch case结构就没有Default的问题

Question

我做了一个radioGroup如上图，用的switch case， default放最后，
但运行后没有default值，一定要点击选中radioButton，才返回值。
附代码。怎样让这RadioGroup在不选中RadioButton的情况下，有默认值47呢
   @Override
        public void onCheckedChanged(RadioGroup group, int checkedId){
           switch (checkedId)
            {              case R.id.Cmajor:
                    n=47;
                    break;
                case R.id.Ebmajor:
                    n=44;
                    case R.id.Emajor:
                    n=43;
                    break;
                case R.id.Fmajor:
                    n=42;
                    break;
                case R.id.Cbmajor:
                    n=46;//47;
                    break;
                case R.id.Dmajor:
                    n=45;//46;
                    break;
                case R.id.Bmajor:
                    n=48;//49;
                   break;
                case R.id.Bbmajor:
                    n=49;//50;
                   break;
                case R.id.Amajor:
                    n=50;//51;
                    break;
                case R.id.Abmajor:
                    n=51;
                    break;
                case R.id.Gmajor:
                    n=52;//53;
                   break;
                case R.id.Gbmajor:
                    n=53;//54;
                    break;
               default:
                    n=47;
                    break;
            }

Answer 1

 你switch default 要执行了switch case都不满足条件才能调用default啊，1：你写个变量默认给个值47  
2：进入程序手动调用下点击事件

Answer 2

你要明白，onCheckedChanged方法是radioButton的选中项改变之后才会调用，如果不改变它是不会调用的；radioButton的选中项改变了，那么它就必须会有一个checkedId，这个checkedId就是那个选中的radioButton，所以你这个switch永远不会跑到default那里去