1 package Test8_19;  2   3 import java.util.Scanner;  4   5 public class CheckDate {  6     public static void main(String args[]) {  7         CheckDate cd = new CheckDate();  8         Scanner reader = new Scanner(System.in);  9         while (true) { 10             System.out.println("Enter a date:"); 11             String date = reader.nextLine(); 12             if (cd.CheckDateFormat(date)) { 13                 System.out.println("Yes"); 14             } else { 15                 System.out.println("No"); 16  17             } 18         } 19     } 20  21     public boolean CheckDateFormat(String date) { 22         String regex = "[1-2]\\d{3}.[0-1][0-9].[0-3][0-9]"; 23  24         if (date.matches(regex)) { 25             // get year month day of String 26             String year = date.substring(0, 4); 27             String month; 28             String day = date.substring(8,10); 29  30             if (date.substring(5, 6).equals("0")) { 31                 month = date.substring(6, 7); // 0-9 month 32             } else { 33                 month = date.substring(5, 7); // 10-12 month 34             } 35  36             if (date.substring(8, 9).equals("0")) { 37                 day = date.substring(9, 10); // 0-9 day 38             } else { 39                 day = date.substring(8, 10); // 10-31 day 40             } 41             // get year month day of int 42             int y = Integer.parseInt(year); 43             int m = Integer.parseInt(month); 44             int d = Integer.parseInt(day); 45             System.out.println("y="+y+" m="+m+" d="+d); 46  47             //if ((m >= 1 && m <= 12) && (d >= 1 && d <= 31)) { 48                 switch(m){ 49                 case 2:if (isLeapYear(y)) { 50                           if (d <= 29) { 51                            return true; 52                            } else { 53                            return false; 54                           } 55                           } 56                           else{ if (d <= 28) { 57                                return true; 58                            } else { 59                            return false; 60                           } 61                           } 62                      63                 case 1: 64                 case 3: 65                 case 5: 66                 case 7: 67                 case 8: 68                 case 10: 69                 case 12:if (d <= 31) { 70                         return true; 71                         } else { 72                         return false; 73                        } 74                 case 4: 75                 case 6: 76                 case 9: 77                 case 11:if (d <= 30) { 78                        return true; 79                       } else { 80                        return false; 81                     } 82                 default:return false; 83                  84                 } 85         } 86         else{ 87           return false; 88         } 89     } 90                  91      92  93     public boolean isLeapYear(int year) { 94         if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) { 95             return true; 96         } else { 97             return false; 98         } 99     }100 101 }