从键盘分别输入年、月、日，判断这一天是当年的第几天

public class SwitchTest3 {
    public static void main(String[] args){
        Scanner scan=new Scanner(System.in);
        System.out.println("请输入year");
        int year=scan.nextInt() ;
        System.out.println("请输入month，0-12");
        int month=scan.nextInt() ;
        System.out.println("请输入day,1-31");
        int days=scan.nextInt();
        int sumDays=0;
        switch(month){//没有写break；会一直往下执行
            case 12:
                sumDays +=30;
            case 11:
                sumDays +=31;
            case 10:
                sumDays +=30;
            case 9:
                sumDays +=31;
            case 8:
                sumDays +=31;
            case 7:
                sumDays +=30;
            case 6:
                sumDays +=31;
            case 5:
                sumDays +=30;
            case 4:
                sumDays +=31; //举个例子，2019年4月3号，刚开始sumDays=0，从case4进去，加上三月的31天
            case 3:
                if(((year%4==0)&&(year%100 !=0))|| year%400==0){

                    sumDays +=29;    //再进去case3，在加上2月的28天
                }else{
                    sumDays +=28;
                }
            case 2:
                sumDays +=31;//再进去case2，在加上1月的31天
            case 1:
                sumDays += days;//再进去case1，在加上days
        }
        System.out.println(sumDays);

    }


}