Fix review suggestions.

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Animal.java

@@ -0,0 +1,6 @@
+package com.baeldung.exceptions.classcastexception;
+
+public interface Animal {
+
+    String getName();
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Box.java

@@ -0,0 +1,14 @@
+package com.baeldung.exceptions.classcastexception;
+
+public class Box<T> {
+
+    private T content;
+
+    public T getContent() {
+        return content;
+    }
+
+    public void setContent(T content) {
+        this.content = content;
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Frog.java

@@ -0,0 +1,9 @@
+package com.baeldung.exceptions.classcastexception;
+
+public class Frog extends Reptile {
+
+    @Override
+    public String getName() {
+        return super.getName() + ": Frog";
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Main.java

@@ -1,94 +0,0 @@
-package com.baeldung.exceptions.classcastexception;
-
-import java.io.Serializable;
-
-public class Main {
-
-    public static void main(String[] args) {
-        checkedCasts();
-        uncheckedConversion();
-        genericConversion();
-    }
-
-    private static void checkedCasts() {
-        Animal animal = new Frog();
-        try {
-            Mammal mammal = (Mammal) animal;
-        } catch (ClassCastException e) {
-            System.out.println("A checked downcast to Mammal is incompatible from Frog because Frog is not a subtype of Mammal.");
-        }
-
-        try {
-            Serializable serial = (Serializable) animal;
-        } catch (ClassCastException e) {
-            System.out.println("A checked cast to Serializable is incompatible from Frog because Frog is not a subtype of Serializable.");
-        }
-
-        Object primitives = new int[1];
-        try {
-            Integer[] integers = (Integer[]) primitives;
-        } catch (ClassCastException e) {
-            System.out.println("A checked cast to Integer[] is incompatible from primitive arrays. Auto-boxing does not work for arrays.");
-        }
-
-        try {
-            long[] longs = (long[]) primitives;
-        } catch (ClassCastException e) {
-            System.out.println("A checked cast to long[] is incompatible from int[]. Type promotion does not work for arrays.");
-        }
-    }
-
-    private static void uncheckedConversion() {
-        Box<Long> originalBox = new Box<>();
-        Box raw = originalBox;
-        raw.setContent(2.5);
-        Box<Long> bound = (Box<Long>) raw;
-        try {
-            Long content = bound.getContent();
-        } catch (ClassCastException e) {
-            System.out.println("An incompatible element was found in the raw box.");
-        }
-    }
-
-    private static void genericConversion() {
-        try {
-            String shouldBeNull = convertInstanceOfObject(123);
-        } catch (ClassCastException e) {
-            System.out.println("Should have been null, but due to type erasure, inside convertInstanceOfObject, " +
-                    "it will attempt to cast to Object instead of String, so it casts to Object, which is always possible.");
-        }
-    }
-
-    public static <T> T convertInstanceOfObject(Object o) {
-        try {
-            return (T) o;
-        } catch (ClassCastException e) {
-            return null;
-        }
-    }
-
-    public interface Animal {
-    }
-
-    public static class Reptile implements Animal {
-    }
-
-    public static class Frog extends Reptile {
-    }
-
-    public static class Mammal implements Animal {
-    }
-
-    public static class Box<T> {
-        private T content;
-
-        public T getContent() {
-            return content;
-        }
-
-        public void setContent(T content) {
-            this.content = content;
-        }
-    }
-
-}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Mammal.java

@@ -0,0 +1,9 @@
+package com.baeldung.exceptions.classcastexception;
+
+public class Mammal implements Animal {
+
+    @Override
+    public String getName() {
+        return "Mammal";
+    }
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Reptile.java

@@ -0,0 +1,9 @@
+package com.baeldung.exceptions.classcastexception;
+
+public class Reptile implements Animal {
+
+    @Override
+    public String getName() {
+        return "Reptile";
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/CheckedCastsUnitTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.exceptions.classcastexception;
+
+import org.junit.Test;
+
+import java.io.Serializable;
+
+public class CheckedCastsUnitTest {
+
+    @Test(expected = ClassCastException.class)
+    public void givenBaseTypeVariableReferencingChildInstance_whenCastToIncompatibleSubtype_thenClassCastException() {
+        Animal animal = new Frog();
+
+        //A checked downcast to Mammal is incompatible from Frog because Frog is not a subtype of Mammal.
+        Mammal mammal = (Mammal) animal;
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void givenBaseTypeVariableReferencingChildInstance_whenCastToIncompatibleInterface_thenClassCastException() {
+        Animal animal = new Frog();
+
+        //A checked cast to Serializable is incompatible from Frog because Frog is not a subtype of Serializable.
+        Serializable serial = (Serializable) animal;
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void givenObjectVariableReferencingPrimitiveArray_whenCastToBoxedTypeArray_thenClassCastException() {
+        Object primitives = new int[1];
+
+        //A checked cast to Integer[] is incompatible from primitive arrays. Auto-boxing does not work for arrays.
+        Integer[] integers = (Integer[]) primitives;
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void givenObjectVariableReferencingPrimitiveArray_whenCastToPromotedTypeArray_thenClassCastException() {
+        Object primitives = new int[1];
+
+        //A checked cast to long[] is incompatible from int[]. Type promotion does not work for arrays.
+        long[] longs = (long[]) primitives;
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/GenericConversionUnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.exceptions.classcastexception;
+
+import org.junit.Test;
+
+public class GenericConversionUnitTest {
+
+    @Test(expected = ClassCastException.class)
+    public void givenIncompatibleType_whenConvertInstanceOfObject_thenClassCastException() {
+        // Should have been null, but due to type erasure, inside convertInstanceOfObject,
+        // it will attempt to cast to Object instead of String, so it casts to Object, which is always possible.
+        String shouldBeNull = convertInstanceOfObject(123);
+    }
+
+    public static <T> T convertInstanceOfObject(Object o) {
+        try {
+            return (T) o; // Casts to Object due to type erasure
+        } catch (ClassCastException e) {
+            return null; // Will never reach this
+        }
+    }
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/classcastexception/UncheckedConversionUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.exceptions.classcastexception;
+
+import org.junit.Test;
+
+public class UncheckedConversionUnitTest {
+
+    @Test(expected = ClassCastException.class)
+    public void givenPollutedGenericType_whenGetProperty_thenClassCastException() {
+        Box<Long> originalBox = new Box<>();
+        Box raw = originalBox;
+        raw.setContent(2.5);
+        Box<Long> bound = (Box<Long>) raw;
+
+        //An incompatible element was found in the raw box.
+        Long content = bound.getContent();
+    }
+}