AgeCalculator changes

core-java/src/main/java/com/baeldung/exceptions/RootCauseFinder.java

@@ -33,28 +33,28 @@ public class RootCauseFinder {
             }
 
             try {
-                return calculateDifference(birthDate).getYears();
+                return Period
+                  .between(parseDate(birthDate), LocalDate.now())
+                  .getYears();
             } catch (DateParseException ex) {
                 throw new CalculationException(ex);
             }
         }
 
-        private static Period calculateDifference(String birthDateAsString) throws DateParseException {
+        private static LocalDate parseDate(String birthDateAsString) throws DateParseException {
 
-            LocalDate birthDate = null;
+            LocalDate birthDate;
             try {
                 birthDate = LocalDate.parse(birthDateAsString);
             } catch (DateTimeParseException ex) {
                 throw new InvalidFormatException(birthDateAsString, ex);
             }
 
-            LocalDate today = LocalDate.now();
+            if (birthDate.isAfter(LocalDate.now())) {
-
-            if (birthDate.isAfter(today)) {
                 throw new DateOutOfRangeException(birthDateAsString);
             }
 
-            return Period.between(birthDate, today);
+            return birthDate;
         }
 
     }

core-java/src/test/java/com/baeldung/exceptions/RootCauseFinderTest.java

@@ -2,9 +2,12 @@ package com.baeldung.exceptions;
 
 import com.google.common.base.Throwables;
 import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.time.LocalDate;
 import java.time.format.DateTimeParseException;
+import java.time.temporal.ChronoUnit;
 
 import static com.baeldung.exceptions.RootCauseFinder.*;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -14,6 +17,19 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  */
 public class RootCauseFinderTest {
 
+    @Test
+    public void givenBirthDate_whenCalculatingAge_thenAgeReturned() {
+        try {
+            int age = AgeCalculator.calculateAge("1990-01-01");
+            Assertions.assertEquals(1990, LocalDate
+              .now()
+              .minus(age, ChronoUnit.YEARS)
+              .getYear());
+        } catch (CalculationException e) {
+            Assertions.fail(e.getMessage());
+        }
+    }
+
     @Test
     public void givenWrongFormatDate_whenFindingRootCauseUsingJava_thenRootCauseFound() {
         try {