Add factory implementations with test scenario (#47)

Author: mperor

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/Animal.java

@@ -0,0 +1,4 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public sealed interface Animal permits Cat, Dog, Fly {
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactory.java

@@ -0,0 +1,6 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public interface AnimalFactory<T> {
+
+    Animal getNewInstance(T type);
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactoryClassImpl.java

@@ -0,0 +1,14 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public class AnimalFactoryClassImpl implements AnimalFactory<Class<? extends Animal>> {
+
+    @Override
+    public Animal getNewInstance(Class<? extends Animal> type) {
+        return switch (type.getSimpleName()) {
+            case Cat.NAME -> new Cat();
+            case Dog.NAME -> new Dog();
+            case Fly.NAME -> new Fly();
+            default -> throw new IllegalStateException("Unexpected value: " + type.getSimpleName());
+        };
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactoryEnumImpl.java

@@ -0,0 +1,30 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+import java.util.function.Supplier;
+
+import static pl.mperor.lab.java.design.pattern.creational.factory.basic.AnimalFactoryEnumImpl.AnimalType;
+
+public class AnimalFactoryEnumImpl implements AnimalFactory<AnimalType> {
+
+    @Override
+    public Animal getNewInstance(AnimalType type) {
+        return type.getCreator().get();
+    }
+
+    public enum AnimalType {
+        DOG(() -> new Dog()),
+        CAT(() -> new Cat()),
+        FLY(() -> new Fly());
+
+        private final Supplier<Animal> creator;
+
+        AnimalType(Supplier<Animal> creator) {
+            this.creator = creator;
+        }
+
+        public Supplier<Animal> getCreator() {
+            return creator;
+        }
+    }
+
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactoryMapImpl.java

@@ -0,0 +1,23 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Supplier;
+
+public class AnimalFactoryMapImpl implements AnimalFactory<String> {
+
+    private final Map<String, Supplier<Animal>> nameToCreator = new HashMap<>();
+
+    public AnimalFactoryMapImpl() {
+        nameToCreator.put(Fly.NAME, () -> new Fly());
+        nameToCreator.put(Dog.NAME, () -> new Dog());
+        nameToCreator.put(Cat.NAME, () -> new Cat());
+    }
+
+    public Animal getNewInstance(String type) {
+        if (nameToCreator.containsKey(type)) {
+            return nameToCreator.get(type).get();
+        }
+        throw new IllegalArgumentException("There is no animal for this name " + type);
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactorySwitchExpressionImpl.java

@@ -0,0 +1,19 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public class AnimalFactorySwitchExpressionImpl implements AnimalFactory<Animal> {
+
+    public static class Instances {
+        public static final Animal CAT = new Cat();
+        public static final Animal DOG = new Dog();
+        public static final Animal FLY = new Fly();
+    }
+
+    @Override
+    public Animal getNewInstance(Animal type) {
+        return switch (type) {
+            case Cat _ -> new Cat();
+            case Dog _ -> new Dog();
+            case Fly _ -> new Fly();
+        };
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/Cat.java

@@ -0,0 +1,11 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public record Cat() implements Animal {
+
+    public static final String NAME = "Cat";
+
+    @Override
+    public String toString() {
+        return NAME;
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/Dog.java

@@ -0,0 +1,11 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public record Dog() implements Animal {
+
+    public static final String NAME = "Dog";
+
+    @Override
+    public String toString() {
+        return NAME;
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/Fly.java

@@ -0,0 +1,12 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+public record Fly() implements Animal {
+
+    public static final String NAME = "Fly";
+
+    @Override
+    public String toString() {
+        return NAME;
+    }
+
+}

DesignPatterns/src/test/java/pl/mperor/lab/java/design/pattern/creational/factory/basic/AnimalFactoryTest.java

@@ -0,0 +1,52 @@
+package pl.mperor.lab.java.design.pattern.creational.factory.basic;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import pl.mperor.lab.java.design.pattern.creational.factory.basic.AnimalFactorySwitchExpressionImpl.Instances;
+
+import static pl.mperor.lab.java.design.pattern.creational.factory.basic.AnimalFactoryEnumImpl.AnimalType;
+
+public class AnimalFactoryTest {
+
+    @Test
+    public void animalFactoryMapImplShouldBeAbleToCreateAnimalsByNames() {
+        AnimalFactory<String> factory = new AnimalFactoryMapImpl();
+        Assertions.assertInstanceOf(Dog.class, factory.getNewInstance("Dog"));
+        Assertions.assertInstanceOf(Fly.class, factory.getNewInstance("Fly"));
+        Assertions.assertInstanceOf(Cat.class, factory.getNewInstance("Cat"));
+
+        Assertions.assertNotSame(factory.getNewInstance("Dog"), factory.getNewInstance("Dog"));
+        Assertions.assertThrows(IllegalArgumentException.class, () -> factory.getNewInstance("Fish"));
+    }
+
+    @Test
+    public void animalFactoryEnumImplShouldBeAbleToCreateAnimalsByEnum() {
+        AnimalFactory<AnimalType> factory = new AnimalFactoryEnumImpl();
+        Assertions.assertInstanceOf(Dog.class, factory.getNewInstance(AnimalType.DOG));
+        Assertions.assertInstanceOf(Fly.class, factory.getNewInstance(AnimalType.FLY));
+        Assertions.assertInstanceOf(Cat.class, factory.getNewInstance(AnimalType.CAT));
+
+        Assertions.assertNotSame(factory.getNewInstance(AnimalType.DOG), factory.getNewInstance(AnimalType.DOG));
+    }
+
+    @Test
+    public void animalFactorySwitchExpressionImplShouldBeAbleToCreateAnimalsByAnimalInstance() {
+        AnimalFactory<Animal> factory = new AnimalFactorySwitchExpressionImpl();
+        Assertions.assertInstanceOf(Dog.class, factory.getNewInstance(Instances.DOG));
+        Assertions.assertInstanceOf(Fly.class, factory.getNewInstance(Instances.FLY));
+        Assertions.assertInstanceOf(Cat.class, factory.getNewInstance(Instances.CAT));
+
+        Assertions.assertNotSame(factory.getNewInstance(Instances.DOG), factory.getNewInstance(Instances.DOG));
+    }
+
+    @Test
+    public void animalFactoryClassImplShouldBeAbleToCreateAnimalsByClass() {
+        AnimalFactory<Class<? extends Animal>> factory = new AnimalFactoryClassImpl();
+        Assertions.assertInstanceOf(Dog.class, factory.getNewInstance(Dog.class));
+        Assertions.assertInstanceOf(Fly.class, factory.getNewInstance(Fly.class));
+        Assertions.assertInstanceOf(Cat.class, factory.getNewInstance(Cat.class));
+
+        Assertions.assertThrows(IllegalStateException.class, () -> factory.getNewInstance(Animal.class));
+        Assertions.assertNotSame(factory.getNewInstance(Dog.class), factory.getNewInstance(Dog.class));
+    }
+}