BAEL-3854 - Pattern Matching for instanceof in Java 14 (#8799)

* BAEL-3491 - Check for null before calling parse in the
Double.parseDouble

* BAEL-3491 - Check for null before calling parse in the
Double.parseDouble

- Return to indentation with spaces.

* BAEL-3854 - Pattern Matching for instanceof in Java 14

* BAEL-3854 - Pattern Matching for instanceof in Java 14 - add unit test

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/patternmatchingforinstanceof/PatternMatchingForInstanceOf.java

@@ -0,0 +1,26 @@
+package com.baeldung.java14.patternmatchingforinstanceof;
+
+public class PatternMatchingForInstanceOf {
+
+    public void performAnimalOperations(Animal animal) {
+         if (animal instanceof Cat cat) {
+             cat.meow();
+         } else if(animal instanceof Dog dog) {
+             dog.woof();
+         }
+    }
+
+    abstract class Animal {
+    }
+
+    final class Cat extends Animal {
+        void meow() {
+        }
+    }
+
+    final class Dog extends Animal {
+        void woof() {
+        }
+    }
+
+}

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/patternmatchingforinstanceof/PatternMatchingForInstanceOfUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.java14.patternmatchingforinstanceof;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.java14.patternmatchingforinstanceof.PatternMatchingForInstanceOf.Cat;
+import com.baeldung.java14.patternmatchingforinstanceof.PatternMatchingForInstanceOf.Dog;
+
+class PatternMatchingForInstanceOfUnitTest {
+
+    @Test
+    void givenAnAnimal_whenTypeIsCat_ThenCatGoesMeow() {
+        Cat animal = mock(Cat.class);
+
+        PatternMatchingForInstanceOf instanceOf = new PatternMatchingForInstanceOf();
+        instanceOf.performAnimalOperations(animal);
+
+        verify(animal).meow();
+    }
+
+    @Test
+    void givenAnAnimal_whenTypeIsDog_ThenDogGoesWoof() {
+        Dog animal = mock(Dog.class);
+
+        PatternMatchingForInstanceOf instanceOf = new PatternMatchingForInstanceOf();
+        instanceOf.performAnimalOperations(animal);
+
+        verify(animal).woof();
+    }
+
+}