Java Program to Validate Date and Print Weekday of the Given Date

Java Program to Validate Date and Print Weekday of the Given Date

// Java program to find the number of days in a month 
// using a switch statement

import java.util.Scanner;

public class Main {

  static int validateDate(int d, int m, int y) {
    if (y >= 1800 && y <= 2999) {
      if (m >= 1 && m <= 12) {
        if (d >= 1 && d <= 31) {
          if ((d >= 1 && d <= 30) && (m == 4 || m == 6 || m == 9 || m == 11))
            return 1; //valid date
          else if ((d >= 1 && d <= 30) && (m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12))
            return 1; //valid date
          else if ((d >= 1 && d <= 28) && (m == 2))
            return 1; //valid date
          else if (d == 29 && m == 2 && ((y % 400 == 0) || (y % 4 == 0 && y % 4 != 0)))
            return 1; //valid date
          else
            return 0; //invalid day
        } else {
          return 0; //day is invalid
        }
      } else {
        return 0; //month is invalid
      }
    } else {
      return 0; //year is invalid
    }
  }

  static int wd(int year, int month, int day) {
    int wday = 0;
    wday = (day + ((153 * (month + 12 * ((14 - month) / 12) - 3) + 2) / 5) +
        (365 * (year + 4800 - ((14 - month) / 12))) +
        ((year + 4800 - ((14 - month) / 12)) / 4) -
        ((year + 4800 - ((14 - month) / 12)) / 100) +
        ((year + 4800 - ((14 - month) / 12)) / 400) -
        32045) %
      7;
    return wday;
  }

  public static void main(String[] args) {
    Scanner SN = new Scanner(System.in);

    int day, month, year;
    int wDayNo = 0;
    String dayNames[] = new String[] {
      "Monday",
      "Tuesday",
      "Wednesday",
      "Thursday",
      "Friday",
      "Saturday",
      "Sunday"
    };

    System.out.printf("Input date: \n");

    System.out.printf("\tEnter day(DD): ");
    day = SN.nextInt();

    System.out.printf("\tEnter month(MM): ");
    month = SN.nextInt();

    System.out.printf("\tEnter year(YYYY): ");
    year = SN.nextInt();

    if (validateDate(day, month, year) == 1) {
      System.out.printf("Date is correct [%02d/%02d/%02d].\n", day, month, year);

      wDayNo = wd(year, month, day);

      System.out.printf("week day is: %s\n", dayNames[wDayNo]);
    } else {
      System.out.printf("Date is in-correct.\n");
    }
  }
}

RUN 1:
Input date: 
        Enter day(DD): 26
        Enter month(MM): 2
        Enter year(YYYY): 2022
Date is correct [26/02/2022].
week day is: Saturday

RUN 2:
Input date: 
        Enter day(DD): 29
        Enter month(MM): 2
        Enter year(YYYY): 2022
Date is in-correct.

RUN 3:
Input date: 
        Enter day(DD): 10
        Enter month(MM): 7
        Enter year(YYYY): 1988
Date is correct [10/07/1988].
week day is: Sunday