Add a class example with the use of Dates

You can se how to calculate from and to an age express in years, months and days.

Author: mhechavarria

DateAndAge.java

@@ -0,0 +1,121 @@
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.time.Period;
+import java.time.ZoneId;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+
+public class DateAndAge {
+	
+	public static Integer[] calculateAge(LocalDate dateOfBirth) {			
+		LocalDate now = LocalDate.now();
+		LocalDate reference = now.minusDays(1);
+		Period diference = Period.between(now, dateOfBirth);
+		
+		int years = Math.abs(diference.getYears());
+		int months = Math.abs(diference.getMonths());
+		int days = Math.abs(diference.getDays());
+						
+		return new Integer[] {years, months, days};
+		 
+	}
+	
+	
+	public static Date calculateDate (int years, int months, int days) {
+		LocalDate now = LocalDate.now(ZoneId.systemDefault());
+		int localDay;
+		if ((months == 1 || months == 3) && days-1 > now.getDayOfMonth()) {
+			localDay = days - 1;
+		}
+		else if ((months == 5) && days-2 > now.getDayOfMonth()) {
+			localDay = days - 2;
+		}
+		else {
+			localDay = days;
+		}
+		Period datePeriod = Period.of(years, months, localDay);
+		
+		LocalDate localDateOfBirth = now.minus(datePeriod);
+		Date dateOfBirth = Date.from(localDateOfBirth.atStartOfDay(ZoneId.systemDefault()).toInstant());
+		
+		localDateOfBirth.getDayOfMonth();
+		return dateOfBirth;
+		
+		
+	}
+	
+	public static LocalDate calculateDate2 (int years, int months, int days) {
+		Period datePeriod = Period.of(years, months, days);
+		LocalDate now = LocalDate.now(ZoneId.systemDefault());
+		LocalDate dateOfBirth = now.minus(datePeriod);
+				
+		return dateOfBirth;
+	}
+	
+	public static void main (String [] args) throws ParseException {
+		//CalcularEdad calcular = new CalcularEdad();
+		//Date fechaReferencia = new Date();
+		
+		int years = 0;
+		int months = 0;
+		int days = 0;
+			
+		// - - - - - - - - - - TEST CONSECUTIVE AGES STARTING WITH A REFERENCE DATE UNTIL AN END DATE - - - - - - - - - - - - - -
+		
+		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
+		Date startDate = formatter.parse("1921-01-01");
+		Date endDate = formatter.parse("2020-31-12");
+		int errors = 0;
+		int pass = 0;
+		int total = 0;
+
+		Calendar start = new GregorianCalendar();
+		start.setTime(startDate);
+		
+		Calendar end = new GregorianCalendar();
+		end.setTime(endDate);
+
+		for (Date date = start.getTime(); start.before(end); start.add(Calendar.DATE, 1), date = start.getTime()) {
+		    // Do your job here with `date`.
+			Calendar customDate = Calendar.getInstance();
+			customDate.setTime(date);
+			
+			//You can play with the final age in year here
+			years = 2022 - start.get(Calendar.YEAR); 
+			months = start.get(Calendar.MONTH);
+			days = start.get(Calendar.DAY_OF_MONTH);
+			
+			LocalDate referenceDate = calculateDate2(years, months, days);
+			Integer estimatedAge [] = calculateAge(referenceDate);
+			if(years != estimatedAge [0] || months != estimatedAge[1] || days != estimatedAge[2]) {
+				Period inAge = Period.of(years, months, days);
+				LocalDate inDate = LocalDate.now().minus(inAge);
+				Period outAge = Period.of(estimatedAge[0], estimatedAge[1], estimatedAge[2]);
+				LocalDate outDate = LocalDate.now().minus(outAge);
+				Period diference = Period.between(inDate, outDate);
+				
+				if(diference.getDays() <=1 && diference.getMonths() == 0 && diference.getYears() == 0) {
+					pass++;
+				}
+				else {
+					errors++;
+				}				
+					    
+			}
+			else {
+				pass++;
+				//System.out.println("P A S S    -    Años: " + edad + "    Meses: " + meses + "    Días: " + dias );
+			}
+		    
+		}
+		total = errors + pass;
+		System.out.println("Total ages test: " + total);
+		System.out.println("Errors: " + errors + " - " + (((float)errors/total)*100) + "%");
+		System.out.println("Pass: " + pass + " - " + (((float)pass/total)*100) + "%");
+		
+		
+	}
+
+}