add calc age test

java-dates/src/main/java/com/baeldung/date/AgeCalculator.java

@@ -0,0 +1,32 @@
+package com.baeldung.date;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.time.Period;
+import java.util.Date;
+import org.joda.time.Years;
+
+public class AgeCalculator {
+
+    public int calculateAge(LocalDate birthDate, LocalDate currentDate) {
+        // validate inputs ...
+        return Period.between(birthDate, currentDate)
+            .getYears();
+    }
+
+    public int calculateAgeWithJodaTime(org.joda.time.LocalDate birthDate, org.joda.time.LocalDate currentDate) {
+        // validate inputs ...
+        Years age = Years.yearsBetween(birthDate, currentDate);
+        return age.getYears();
+    }
+
+    public int calculateAgeWithJava7(Date birthDate, Date currentDate) {
+        // validate inputs ...
+        DateFormat formatter = new SimpleDateFormat("yyyyMMdd");
+        int d1 = Integer.parseInt(formatter.format(birthDate));
+        int d2 = Integer.parseInt(formatter.format(currentDate));
+        int age = (d2 - d1) / 10000;
+        return age;
+    }
+}

java-dates/src/test/java/com/baeldung/date/AgeCalculatorUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.date;
+
+import static org.junit.Assert.assertEquals;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.util.Date;
+import org.junit.jupiter.api.Test;
+
+public class AgeCalculatorUnitTest {
+    AgeCalculator ageCalculator = new AgeCalculator();
+
+    @Test
+    public void givenLocalDate_whenCalculateAge_thenOk() {
+        assertEquals(10, ageCalculator.calculateAge(LocalDate.of(2008, 5, 20), LocalDate.of(2018, 9, 20)));
+    }
+
+    @Test
+    public void givenJodaTime_whenCalculateAge_thenOk() {
+        assertEquals(10, ageCalculator.calculateAgeWithJodaTime(new org.joda.time.LocalDate(2008, 5, 20), new org.joda.time.LocalDate(2018, 9, 20)));
+    }
+
+    @Test
+    public void givenDate_whenCalculateAge_thenOk() throws ParseException {
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
+        Date birthDate = sdf.parse("2008-05-20");
+        Date currentDate = sdf.parse("2018-09-20");
+        assertEquals(10, ageCalculator.calculateAgeWithJava7(birthDate, currentDate));
+    }
+
+}