Bael 5275 (#11561)

* Initial impl of enum

* Added Java 8 based enum searcher and test for it.

* Moved code to core-java-enums

* Fixed test name and readme

* Reused existing module core-java-modules/core-java-lang-oop-types-2 instead of creating a new one.

* Reused existing module core-java-modules/core-java-lang-oop-types-2 instead of creating a new one.

core-java-modules/core-java-lang-oop-types-2/README.md

@@ -5,3 +5,4 @@ This module contains articles about types in Java
 ### Relevant Articles: 
 
 - [Convert an Array of Primitives to an Array of Objects](https://www.baeldung.com/java-primitive-array-to-object-array)
+- [Check if an Enum Value Exists in Java](https://www.baeldung.com/java-find-enum-by-criteria)

core-java-modules/core-java-lang-oop-types-2/src/main/java/com/baeldung/enums/Direction.java

@@ -0,0 +1,26 @@
+package com.baeldung.enums;
+
+/**
+ * Represents directions.
+ */
+public enum Direction {
+    EAST, WEST, SOUTH, NORTH;
+
+    /**
+     * Finds direction by name.
+     *
+     * @param name the name
+     * @return the direction if found else null
+     */
+    public static Direction findByName(String name) {
+        Direction result = null;
+        for (Direction direction : values()) {
+            if (direction.name().equalsIgnoreCase(name)) {
+                result = direction;
+                break;
+            }
+        }
+        return result;
+    }
+
+}

core-java-modules/core-java-lang-oop-types-2/src/main/java/com/baeldung/enums/EnumSearcher.java

@@ -0,0 +1,19 @@
+package com.baeldung.enums;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class EnumSearcher {
+    private static final Logger LOG = LoggerFactory.getLogger(EnumSearcher.class);
+
+    public static void main(String[] args) {
+        EnumSearcher enumSearcher = new EnumSearcher();
+        enumSearcher.printWeekdays();
+    }
+
+    private void printWeekdays() {
+        for (Weekday day: Weekday.values()) {
+            LOG.info("Name {}, Value {}, Stringified {}", day.name(), day.getValue(), day);
+        }
+    }
+}

core-java-modules/core-java-lang-oop-types-2/src/main/java/com/baeldung/enums/Month.java

@@ -0,0 +1,116 @@
+package com.baeldung.enums;
+
+import java.util.Arrays;
+import java.util.Optional;
+
+/**
+ * Represents months in a year.
+ */
+public enum Month {
+    /**
+     * January.
+     */
+    JANUARY("January", 1),
+    /**
+     * February.
+     */
+    FEBRUARY("February", 2),
+    /**
+     * March.
+     */
+    MARCH("March", 3),
+    /**
+     * April.
+     */
+    APRIL("April", 4),
+    /**
+     * May.
+     */
+    MAY("May", 5),
+    /**
+     * June.
+     */
+    JUNE("June", 6),
+    /**
+     * July.
+     */
+    JULY("July", 7),
+    /**
+     * August.
+     */
+    AUGUST("August", 8),
+    /**
+     * September.
+     */
+    SEPTEMBER("September", 9),
+    /**
+     * October.
+     */
+    OCTOBER("October", 10),
+    /**
+     * November.
+     */
+    NOVEMBER("November", 11),
+    /**
+     * December.
+     */
+    DECEMBER("December", 12),
+    ;
+
+    private final String value;
+    private final int code;
+
+    Month(String value, int code) {
+        this.value = value;
+        this.code = code;
+    }
+
+    /**
+     * Gets value.
+     *
+     * @return the value
+     */
+    public String getValue() {
+        return value;
+    }
+
+    /**
+     * Gets code.
+     *
+     * @return the code
+     */
+    public int getCode() {
+        return code;
+    }
+
+    /**
+     * Find by name.
+     *
+     * @param name the name
+     * @return the month if found else <code>Optional.empty()</code>
+     */
+    public static Optional<Month> findByName(String name) {
+        return Arrays.stream(values()).filter(month -> month.name().equalsIgnoreCase(name)).findFirst();
+    }
+
+    /**
+     * Find by code.
+     *
+     * @param code the code
+     * @return the month if found else <code>Optional.empty()</code>
+     */
+    public static Optional<Month> findByCode(int code) {
+        return Arrays.stream(values()).filter(month -> month.getCode() == code).findFirst();
+    }
+
+    /**
+     * Finds month by value.
+     *
+     * @param value value
+     * @return month if value is valid
+     * @throws IllegalArgumentException if month not found for given value
+     */
+    public static Month findByValue(String value) {
+        return Arrays.stream(values()).filter(month -> month.getValue().equalsIgnoreCase(value)).findFirst().orElseThrow(IllegalArgumentException::new);
+    }
+}

core-java-modules/core-java-lang-oop-types-2/src/main/java/com/baeldung/enums/Weekday.java

@@ -0,0 +1,85 @@
+package com.baeldung.enums;
+
+/**
+ * Represents day in a week.
+ */
+public enum Weekday {
+    /**
+     * Monday.
+     */
+    MONDAY("Monday"),
+    /**
+     * Tuesday.
+     */
+    TUESDAY("Tuesday"),
+    /**
+     * Wednesday.
+     */
+    WEDNESDAY("Wednesday"),
+    /**
+     * Thursday.
+     */
+    THURSDAY("Thursday"),
+    /**
+     * Friday.
+     */
+    FRIDAY("Friday"),
+    /**
+     * Saturday.
+     */
+    SATURDAY("Saturday"),
+    /**
+     * Sunday.
+     */
+    SUNDAY("Sunday"),
+    ;
+
+    private final String value;
+
+    Weekday(String value) {
+        this.value = value;
+    }
+
+    /**
+     * Gets value.
+     *
+     * @return the value
+     */
+    public String getValue() {
+        return value;
+    }
+
+    /**
+     * Find by name.
+     *
+     * @param name the name
+     * @return the weekday if found else null
+     */
+    public static Weekday findByName(String name) {
+        Weekday result = null;
+        for (Weekday day : values()) {
+            if (day.name().equalsIgnoreCase(name)) {
+                result = day;
+                break;
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Find by value.
+     *
+     * @param value the value
+     * @return the weekday if found else null
+     */
+    public static Weekday findByValue(String value) {
+        Weekday result = null;
+        for (Weekday day : values()) {
+            if (day.getValue().equalsIgnoreCase(value)) {
+                result = day;
+                break;
+            }
+        }
+        return result;
+    }
+}

core-java-modules/core-java-lang-oop-types-2/src/test/java/com/baeldung/enums/EnumSearcherUnitTest.java

@@ -0,0 +1,89 @@
+package com.baeldung.enums;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+public class EnumSearcherUnitTest {
+
+    @Test
+    public void givenWeekdays_whenValidDirectionNameProvided_directionIsFound() {
+        Direction result = Direction.findByName("EAST");
+        Assertions.assertThat(result).isEqualTo(Direction.EAST);
+    }
+
+    @Test
+    public void givenWeekdays_whenValidDirectionNameLowerCaseProvided_directionIsFound() {
+        Direction result = Direction.findByName("east");
+        Assertions.assertThat(result).isEqualTo(Direction.EAST);
+    }
+
+    @Test
+    public void givenWeekdays_whenInvalidDirectionNameProvided_nullIsReturned() {
+        Direction result = Direction.findByName("E");
+        Assertions.assertThat(result).isNull();
+    }
+
+    @Test
+    public void givenWeekdays_whenValidWeekdayNameProvided_weekdayIsFound() {
+        Weekday result = Weekday.findByName("MONDAY");
+        Assertions.assertThat(result).isEqualTo(Weekday.MONDAY);
+    }
+
+    @Test
+    public void givenWeekdays_whenInvalidWeekdayNameProvided_nullIsReturned() {
+        Weekday result = Weekday.findByName("MON");
+        Assertions.assertThat(result).isNull();
+    }
+
+    @Test
+    public void givenWeekdays_whenValidWeekdayValueProvided_weekdayIsFound() {
+        Weekday result = Weekday.findByValue("Monday");
+        Assertions.assertThat(result).isEqualTo(Weekday.MONDAY);
+    }
+
+    @Test
+    public void givenWeekdays_whenInvalidWeekdayValueProvided_nullIsReturned() {
+        Weekday result = Weekday.findByValue("mon");
+        Assertions.assertThat(result).isNull();
+    }
+
+    @Test
+    public void givenMonths_whenValidMonthNameProvided_optionalMonthIsReturned() {
+        Optional<Month> result = Month.findByName("JANUARY");
+        Assertions.assertThat(result).isEqualTo(Optional.of(Month.JANUARY));
+    }
+
+    @Test
+    public void givenMonths_whenInvalidMonthNameProvided_optionalEmptyIsReturned() {
+        Optional<Month> result = Month.findByName("JAN");
+        Assertions.assertThat(result).isEmpty();
+    }
+
+    @Test
+    public void givenMonths_whenValidMonthCodeProvided_optionalMonthIsReturned() {
+        Optional<Month> result = Month.findByCode(1);
+        Assertions.assertThat(result).isEqualTo(Optional.of(Month.JANUARY));
+    }
+
+    @Test
+    public void givenMonths_whenInvalidMonthCodeProvided_optionalEmptyIsReturned() {
+        Optional<Month> result = Month.findByCode(0);
+        Assertions.assertThat(result).isEmpty();
+    }
+
+    @Test
+    public void givenMonths_whenValidMonthValueProvided_monthIsReturned() {
+        Month result = Month.findByValue("January");
+        Assertions.assertThat(result).isEqualTo(Month.JANUARY);
+    }
+
+    @Test
+    public void givenMonths_whenInvalidMonthValueProvided_illegalArgExIsThrown() {
+        assertThatIllegalArgumentException().isThrownBy(() -> Month.findByValue("Jan"));
+    }
+}