用户输入一个年份和一个月份，输出该月的天数Java

public static void main(String[] args) {
        Scanner sc = new Scanner();
        ("请输入一个年份：");
        int year=();
        ("请输入一个月份：");
        int month=();

        switch (month){
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:(year+"年"+month+"月为31天");break;
            case 4:
            case 6:
            case 9:
            case 11:(year+"年"+month+"月为30天");break;
            case 2:
                //判断平年闰年
                if(year%4 == 0 && year%100 != 0 || year%400 == 0){
                    (year+"年"+month+"月为29天");
                }else{
                    (year+"年"+month+"月为28天");
                }
                break;
            default:
                ("输入有误！");break;
        }

    }