用switch结构实现判断日期是这一年的第几天

public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.print("请输入年份："); int year = sc.nextInt(); System.out.print("请输入月份："); int month = sc.nextInt(); System.out.print("请输入天数："); int day = sc.nextInt(); switch (month) { case 12: day = 30; case 11: day = 31; case 10: day = 30; case 9: day = 31; case 8: day = 31; case 7: day = 30; case 6: day = 31; case 5: day = 30; case 4: day = 31; case 3: if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) { day = 29; } else { day = 28; } case 2: day = 31; case 1: System.out.println(day); break; default: System.out.println("请输入正确的时间"); break; } System.out.println("这是" year "年" "第" day "天"); }