Bael-1604 (#3765)

* BAEL-1604

* BAEL-1604

core-java/src/main/java/com/baeldung/casting/AnimalFeederGeneric.java

@@ -0,0 +1,24 @@
+package com.baeldung.casting;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class AnimalFeederGeneric<T> {
+    private Class<T> type;
+
+    public AnimalFeederGeneric(Class<T> type) {
+        this.type = type;
+    }
+
+    public List<T> feed(List<Animal> animals) {
+        List<T> list = new ArrayList<T>();
+        animals.forEach(animal -> {
+            if (type.isInstance(animal)) {
+                T objAsType = type.cast(animal);
+                list.add(objAsType);
+            }
+        });
+        return list;
+    }
+
+}

core-java/src/test/java/com/baeldung/casting/CastingTest.java

@@ -11,6 +11,7 @@ public class CastingTest {
     public void whenPrimitiveConverted_thenValueChanged() {
         double myDouble = 1.1;
         int myInt = (int) myDouble;
+
         assertNotEquals(myDouble, myInt);
     }
 
@@ -55,4 +56,25 @@ public class CastingTest {
         animals.add(new Dog());
         new AnimalFeeder().uncheckedFeed(animals);
     }
+
+    @Test
+    public void whenDowncastToCatWithCastMethod_thenMeowIsCalled() {
+        Animal animal = new Cat();
+        if (Cat.class.isInstance(animal)) {
+            Cat cat = Cat.class.cast(animal);
+            cat.meow();
+        }
+    }
+    
+    @Test
+    public void whenParameterCat_thenOnlyCatsFed() {
+        List<Animal> animals = new ArrayList<>();
+        animals.add(new Cat());
+        animals.add(new Dog());
+        AnimalFeederGeneric<Cat> catFeeder = new AnimalFeederGeneric<Cat>(Cat.class);
+        List<Cat> fedAnimals = catFeeder.feed(animals);
+
+        assertTrue(fedAnimals.size() == 1);
+        assertTrue(fedAnimals.get(0) instanceof Cat);
+    }
 }