Use LocalDate in baffling birthdays

LocalData is a more idiomatic way of representing dates in Java.

Author: kahgoh

exercises/practice/baffling-birthdays/.meta/src/reference/java/BafflingBirthdays.java

@@ -9,27 +9,25 @@ class BafflingBirthdays {
     private static final int nonLeapYear = 2001;
     private static final int daysInYear = 365;
 
-    boolean sharedBirthday(List<String> birthdates) {
+    boolean sharedBirthday(List<LocalDate> birthdates) {
         Set<String> seen = new HashSet<>();
-        for (String birthdate : birthdates) {
-            String monthDay = birthdate.substring(5);
-            if (!seen.add(monthDay)) {
+        for (LocalDate birthdate : birthdates) {
+            if (!seen.add(birthdate.getMonth().toString() + birthdate.getDayOfMonth())) {
                 return true;
             }
         }
         return false;
     }
 
-    List<String> randomBirthdates(int groupSize) {
+    List<LocalDate> randomBirthdates(int groupSize) {
         if (groupSize <= 0) {
             return List.of();
         }
-        List<String> birthdates = new ArrayList<>(groupSize);
+        List<LocalDate> birthdates = new ArrayList<>(groupSize);
         ThreadLocalRandom random = ThreadLocalRandom.current();
         for (int i = 0; i < groupSize; i++) {
             int dayOfYear = random.nextInt(1, daysInYear + 1);
-            LocalDate date = LocalDate.ofYearDay(nonLeapYear, dayOfYear);
-            birthdates.add(date.toString());
+            birthdates.add(LocalDate.ofYearDay(nonLeapYear, dayOfYear));
         }
         return birthdates;
     }

exercises/practice/baffling-birthdays/src/main/java/BafflingBirthdays.java

@@ -1,11 +1,12 @@
+import java.time.LocalDate;
 import java.util.List;
 
 class BafflingBirthdays {
-    boolean sharedBirthday(List<String> birthdates) {
+    boolean sharedBirthday(List<LocalDate> birthdates) {
         throw new UnsupportedOperationException("Delete this statement and write your own implementation.");
     }
 
-    List<String> randomBirthdates(int groupSize) {
+    List<LocalDate> randomBirthdates(int groupSize) {
         throw new UnsupportedOperationException("Delete this statement and write your own implementation.");
     }
 

exercises/practice/baffling-birthdays/src/test/java/BafflingBirthdaysTest.java

@@ -1,83 +1,117 @@
+import java.time.LocalDate;
+import java.util.List;
+
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
+import static java.time.Month.APRIL;
+import static java.time.Month.AUGUST;
+import static java.time.Month.DECEMBER;
+import static java.time.Month.FEBRUARY;
+import static java.time.Month.JANUARY;
+import static java.time.Month.JULY;
+import static java.time.Month.MAY;
+import static java.time.Month.NOVEMBER;
+import static java.time.Month.OCTOBER;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;
 
-import java.time.LocalDate;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-
 public class BafflingBirthdaysTest {
     private BafflingBirthdays birthdays = new BafflingBirthdays();
 
     @Test
     @DisplayName("one birthdate")
     public void oneBirthdateTest() {
-        assertThat(birthdays.sharedBirthday(List.of("2000-01-01"))).isFalse();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(2000, JANUARY, 1)
+        ))).isFalse();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("two birthdates with same year, month, and day")
     public void twoBirthdatesWithSameYearMonthAndDayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("2000-01-01", "2000-01-01"))).isTrue();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(2000, JANUARY, 1),
+                LocalDate.of(2000, JANUARY, 1)
+        ))).isTrue();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("two birthdates with same year and month, but different day")
     public void twoBirthdatesWithSameYearAndMonthButDifferentDayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("2012-05-09", "2012-05-17"))).isFalse();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(2012, MAY, 9),
+                LocalDate.of(2012, MAY, 17)
+        ))).isFalse();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("two birthdates with same month and day, but different year")
     public void twoBirthdatesWithSameMonthAndDayButDifferentYearTest() {
-        assertThat(birthdays.sharedBirthday(List.of("1999-10-23", "1988-10-23"))).isTrue();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(1999, OCTOBER, 23),
+                LocalDate.of(1988, OCTOBER, 23)
+        ))).isTrue();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("two birthdates with same year, but different month and day")
     public void twoBirthdatesWithSameYearButDifferentMonthAndDayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("2007-12-19", "2007-04-27"))).isFalse();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(2007, DECEMBER, 19),
+                LocalDate.of(2007, APRIL, 27)
+        ))).isFalse();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("two birthdates with different year, month, and day")
     public void twoBirthdatesWithDifferentYearMonthAndDayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("1997-08-04", "1963-11-23"))).isFalse();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(1997, AUGUST, 4),
+                LocalDate.of(1963, NOVEMBER, 23)
+        ))).isFalse();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("multiple birthdates without shared birthday")
     public void multipleBirthdatesWithoutSharedBirthdayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("1966-07-29", "1977-02-12", "2001-12-25", "1980-11-10"))).isFalse();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(1966, AUGUST, 29),
+                LocalDate.of(1977, FEBRUARY, 12),
+                LocalDate.of(2001, DECEMBER, 25),
+                LocalDate.of(1980, NOVEMBER, 10)
+        ))).isFalse();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("multiple birthdates with one shared birthday")
     public void multipleBirthdatesWithOneSharedBirthdayTest() {
-        assertThat(birthdays.sharedBirthday(List.of("1966-07-29", "1977-02-12", "2001-07-29", "1980-11-10"))).isTrue();
+        assertThat(birthdays.sharedBirthday(List.of(
+                LocalDate.of(1966, AUGUST, 29),
+                LocalDate.of(1977, FEBRUARY, 12),
+                LocalDate.of(2001, AUGUST, 29),
+                LocalDate.of(1980, NOVEMBER, 10)
+        ))).isTrue();
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("multiple birthdates with more than one shared birthday")
     public void multipleBirthdatesWithMoreThanOneSharedBirthdayTest() {
         assertThat(birthdays.sharedBirthday(List.of(
-                "1966-07-29",
-                "1977-02-12",
-                "2001-12-25",
-                "1980-07-29",
-                "2019-02-12"
+                LocalDate.of(1966, JULY, 29),
+                LocalDate.of(1977, FEBRUARY, 12),
+                LocalDate.of(2001, DECEMBER, 25),
+                LocalDate.of(1980, JULY, 29),
+                LocalDate.of(2019, FEBRUARY, 12)
         ))).isTrue();
     }
 
@@ -93,41 +127,23 @@ public void generateRequestedNumberOfBirthdatesTest() {
     @Test
     @DisplayName("years are not leap years")
     public void yearsAreNotLeapYearsTest() {
-        for (String birthdate : birthdays.randomBirthdates(100)) {
-            LocalDate date = LocalDate.parse(birthdate);
-            assertThat(date.isLeapYear()).isFalse();
-            assertThat(date.getMonthValue() == 2 && date.getDayOfMonth() == 29).isFalse();
-        }
+        assertThat(birthdays.randomBirthdates(100)).noneMatch(LocalDate::isLeapYear);
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("months are random")
     public void monthsAreRandomTest() {
-        Set<Integer> months = new HashSet<>();
-        for (String birthdate : birthdays.randomBirthdates(500)) {
-            LocalDate date = LocalDate.parse(birthdate);
-            months.add(date.getMonthValue());
-            if (months.size() >= 7) {
-                break;
-            }
-        }
-        assertThat(months).hasSizeGreaterThanOrEqualTo(7);
+        assertThat(birthdays.randomBirthdates(500).stream().map(LocalDate::getMonth).distinct())
+                .hasSizeGreaterThanOrEqualTo(7);
     }
 
     @Disabled("Remove to run test")
     @Test
     @DisplayName("days are random")
     public void daysAreRandomTest() {
-        Set<Integer> days = new HashSet<>();
-        for (String birthdate : birthdays.randomBirthdates(500)) {
-            LocalDate date = LocalDate.parse(birthdate);
-            days.add(date.getDayOfMonth());
-            if (days.size() >= 11) {
-                break;
-            }
-        }
-        assertThat(days).hasSizeGreaterThanOrEqualTo(11);
+        assertThat(birthdays.randomBirthdates(500).stream().map(LocalDate::getDayOfMonth).distinct())
+                .hasSizeGreaterThanOrEqualTo(11);
     }
 
     @Disabled("Remove to run test")