JavaCode - Example to calculate age and DOB

CalculateAgeDOB

public class Test
{
	public static void main(String args[])
	{
		Year birthYear = new Year(27, 10, 1989);
		Year endYear = new Year(3, 5, 2017);

		new AgeCalculate()
		{
			@Override
			protected void getResult(String result)
			{
				System.out.println(result);
			}
		}.calculateAGE(birthYear, endYear);

		System.out.println("\n");

		Year date = new Year(3, 5, 2017);
		Year ageAt = new Year(7, 6, 27);

		new AgeCalculate()
		{
			@Override
			protected void getResult(final String result)
			{
				System.out.println(result);
			}
		}.calculateDOB(date, ageAt);
	}

	public static abstract class AgeCalculate
	{
		protected abstract void getResult(String result);

		public AgeCalculate()
		{
		}

		public void calculateAGE(Year dateOfBirth, Year ageAtTheDateOf)
		{
			if (ageAtTheDateOf.year < dateOfBirth.year)
			{
				getResult("dateOfBirth can no be greater than ageAtTheDateOf.");
			}//Date of birth needs to be earlier than the age at date.

			long years = ageAtTheDateOf.year - (dateOfBirth.year + 1);
			long months = years * 12;
			long days = 0;

			//Calculate the days.
			for (int index = 0; index < years; index++)
			{
				int year = dateOfBirth.year + index;
				if (!isLeapYear(year))
				{
					days += 365;
				}
				else
				{
					days += 366;
				}
			}

			long monthInclude;
			if (ageAtTheDateOf.month == 0)
			{
				monthInclude = (12 - dateOfBirth.month);
			}
			else
			{
				monthInclude = (12 - dateOfBirth.month) + (ageAtTheDateOf.month - 1);
			}


			long dayInclude = (daysInPriorMonth(dateOfBirth.month, dateOfBirth.year) - dateOfBirth.day) + (ageAtTheDateOf.day);

			for (int index = 12; index > dateOfBirth.month; index--)
			{
				days += daysInPriorMonth(index, dateOfBirth.year);
			}

			for (int index = 1; index < ageAtTheDateOf.month; index++)
			{
				days += daysInPriorMonth(index, dateOfBirth.year);
			}

			days += dayInclude;

			String age;
			age = "YOUR AGE IS " + years + " Years " + monthInclude + " Months and " +
					dayInclude + " Days(" + (daysInPriorMonth(dateOfBirth.month, dateOfBirth.year) - dateOfBirth.day) + " Days of " + dateOfBirth.month + "/" + dateOfBirth.year
					+ " and " + ageAtTheDateOf.day + " Days of " + ageAtTheDateOf.month + "/" + ageAtTheDateOf.year + ")";
			age += "\n";
			age += "AGE IN DAYS : " + days + " Days.";
			age += "\n";
			age += "AGE IN HOURS : " + (days * 24) + " Hours.";
			age += "\n";
			age += "AGE IN SECONDS : " + ((days * 24) * 60) + " Minutes.";
			age += "\n";
			age += "AGE IN MILLISECONDS : " + (((days * 24) * 60) * 1000) + " Milli Seconds.";

			getResult(age);
		}

		public void calculateDOB(Year date, Year ageAt)
		{
			if (!isValidateNumber(date.day, 1, 31, "Day of cal") ||
					!isValidateNumber(date.year, 0, 2999, "Year of cal") ||
					!isValidateNumber(ageAt.year, 0, 1000, "Years aged") ||
					!isValidateNumber(ageAt.month, 0, 11, "Months aged") ||
					!isValidateNumber(ageAt.day, 0, 30, "Days aged"))
			{
				return;
			}

//			Year result1 = diffDateAgeAndOutput(date.year, date.month, date.day, ageAt.year, ageAt.month, ageAt.day, 1); // Assume 30-day months
			Year result2 = diffDateAgeAndOutput(date.year, date.month, date.day, ageAt.year, ageAt.month, ageAt.day, 2); // Borrow from month before death
//			Year result3 = diffDateAgeAndOutput(date.year, date.month, date.day, ageAt.year, ageAt.month, ageAt.day, 3); // Days alive in birth and death months

//			getResult(result1.toString());
			getResult(result2.toString());
//			getResult(result3.toString());
		}

		private boolean isValidateNumber(int num, int min, int max, String msg)
		{
			if (num < min || max < num)
			{
				getResult(msg + " not in range [" + min + "..." + max + "]");
				return false;
			}
			return true;
		}

		private Year diffDateAgeAndOutput(int yd, int md, int dd, int ya, int ma, int da, int method)
		{
			int db = dd - da,
					mb = md - ma,
					yb = yd - ya;

			if (db < 1)
			{
				// Multiple ways to handle this!
				switch (method)
				{
					case 1: //ASSUME30:
						// 1. can always borrow 30 days.
						db += 30;
						break;

					case 2: //BORROW:
						// 2. Can borrow number of days in previous month.
						db += daysInPriorMonth(md, yd);
						//	  Will possible leave -1 or -2 for number of days
						if (db < 1)
						{
							// can still be negative if borrowed from February
							md -= 1;
							if (md < 0)
							{
								md = 11;
								yd -= 1;
							}
							db += daysInPriorMonth(md, yd);
							mb -= 1;
						}
						break;

					case 3://EXACT:
						// 3. can count days alive in birth month plus days alive in death month, -1
						db += daysInPriorMonth(mb, yb);
						if (db < 1)
						{
							mb -= 1;
							if (mb < 0)
							{
								mb = 11;
								yd -= 1;
							}
							db += daysInPriorMonth(mb, yb);
						}
						break;
				}
				mb -= 1;
			}
			if (mb < 0)
			{
				// borrow 12 months from year of death
				mb += 12;
				yb -= 1;
			}

			return new Year(db, mb, yb);
		}

		private boolean isLeapYear(int year)
		{
			String x = String.valueOf((double) year / 4);
			return x.contains(".");
		}

		private int daysInPriorMonth(int month, int year)
		{
			if (month == 1) //January
			{
				return 31;
			}

			if (month == 2) //February
			{
				if (isLeapYear(year))
				{
					return 29;
				}
				else
				{
					return 28;
				}
			}

			if (month == 3) //March
			{
				return 31;
			}

			if (month == 4) //April
			{
				return 30;
			}

			if (month == 5) //may
			{
				return 31;
			}

			if (month == 6) //June
			{
				return 30;
			}

			if (month == 7) //July
			{
				return 31;
			}

			if (month == 8) //august
			{
				return 31;
			}

			if (month == 9) // September
			{
				return 30;
			}

			if (month == 10) //October
			{
				return 31;
			}

			if (month == 11) //November
			{
				return 30;
			}

			if (month == 12) //December
			{
				return 31;
			}

			return 0;
		}
	}

	public static class Year
	{
		private static final String[] monthNames = new String[]{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
				"Oct", "Nov", "Dec"};
		int day;
		int month;
		int year;

		public Year(int day, int month, int year)
		{
			this.day = day;
			this.month = month;
			this.year = year;
		}

		@Override
		public String toString()
		{
			return day + " " + monthNames[month - 1] + " " + year;
		}
	}
}