Added the code for Abstract factory pattern implementation and its unit test

Author: abhijay94

src/main/java/com/designpatterns/creational/abstractfactory/AbstractShapeFactory.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+/**
+ * The abstract factory pattern provides a way to encapsulate a group of individual factories that have a common theme
+ * without specifying their concrete classes. In normal usage, the client software creates a concrete implementation of
+ * the abstract factory and then uses the generic interface of the factory to create the concrete objects that are part
+ * of the theme. The client doesn't know (or care) which concrete objects it gets from each of these internal factories,
+ * since it uses only the generic interfaces of their products.
+ * <p>
+ * This pattern separates the details of implementation of a set of objects from their general usage and relies on
+ * object composition, as object creation is implemented in methods exposed in the factory interface.
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Abstract_factory_pattern">Abstract Factory Pattern</a>
+ */
+public abstract class AbstractShapeFactory {
+    /**
+     * Creates the appropriate shape object depending on the type of the shape
+     *
+     * @param name enum defining the name of the shape
+     * @return shape object
+     */
+    public abstract Shape getShape(ShapeType name);
+}

src/main/java/com/designpatterns/creational/abstractfactory/Circle.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class Circle implements Shape {
+    @Override
+    public double surfaceArea(float radius) {
+        return Math.PI * radius * radius;
+    }
+
+    @Override
+    public ShapeType getShapeType() {
+        return ShapeType.CIRCLE;
+    }
+}

src/main/java/com/designpatterns/creational/abstractfactory/FactoryProvider.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class FactoryProvider {
+    public static AbstractShapeFactory getShapeFactory(FactoryType factoryType) {
+        if (FactoryType.TWO_D_FACTORY == factoryType) {
+            return new TwoDShapeFactory();
+        } else if (FactoryType.THREE_D_FACTORY == factoryType) {
+            return new ThreeDShapeFactory();
+        }
+        return null;
+    }
+}

src/main/java/com/designpatterns/creational/abstractfactory/FactoryType.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public enum FactoryType {
+    TWO_D_FACTORY,
+    THREE_D_FACTORY
+}

src/main/java/com/designpatterns/creational/abstractfactory/Line.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class Line implements Shape {
+    @Override
+    public double surfaceArea(float radius) {
+        return 0;
+    }
+
+    @Override
+    public ShapeType getShapeType() {
+        return ShapeType.LINE;
+    }
+}

src/main/java/com/designpatterns/creational/abstractfactory/Shape.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public interface Shape {
+    /**
+     * calculates the surface area for the shape object
+     *
+     * @param radius the radius or length of shape whose area is to be calculated
+     * @return total surface area for the shape
+     */
+    double surfaceArea(float radius);
+
+    /**
+     * A property to identity the type of the shape for testing the pattern
+     *
+     * @return an enum describing the shape type
+     */
+    ShapeType getShapeType();
+}

src/main/java/com/designpatterns/creational/abstractfactory/ShapeType.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public enum ShapeType {
+    LINE,
+    CIRCLE,
+    SPHERE
+}

src/main/java/com/designpatterns/creational/abstractfactory/Sphere.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class Sphere implements Shape {
+    @Override
+    public double surfaceArea(float radius) {
+        return 4 * Math.PI * radius * radius;
+    }
+
+    @Override
+    public ShapeType getShapeType() {
+        return ShapeType.SPHERE;
+    }
+}

src/main/java/com/designpatterns/creational/abstractfactory/ThreeDShapeFactory.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class ThreeDShapeFactory extends AbstractShapeFactory {
+    @Override
+    public Shape getShape(ShapeType name) {
+        if (ShapeType.SPHERE == name) {
+            return new Sphere();
+        }
+        return null;
+    }
+}

src/main/java/com/designpatterns/creational/abstractfactory/TwoDShapeFactory.java

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+package src.main.java.com.designpatterns.creational.abstractfactory;
+
+public class TwoDShapeFactory extends AbstractShapeFactory {
+    @Override
+    public Shape getShape(ShapeType name) {
+        if (ShapeType.LINE == name) {
+            return new Line();
+        } else if (ShapeType.CIRCLE == name) {
+            return new Circle();
+        }
+        return null;
+    }
+}

src/test/java/com/designpatterns/creational/abstractfactory/AbstractShapeFactoryTest.java

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+package src.test.java.com.designpatterns.creational.abstractfactory;
+
+import org.junit.Assert;
+import org.junit.Test;
+import src.main.java.com.designpatterns.creational.abstractfactory.*;
+
+public class AbstractShapeFactoryTest {
+    @Test
+    public void testAbstractShapeFactory() {
+        String failReason = "";
+        // Tests for 2-D shape factory
+        // Test for Line
+        AbstractShapeFactory shapeFactory = FactoryProvider.getShapeFactory(FactoryType.TWO_D_FACTORY);
+        Shape shape = shapeFactory.getShape(ShapeType.LINE);
+        if (shape.getShapeType() != ShapeType.LINE) {
+            failReason += "Could not create an object for LINE.\n";
+        }
+        if (shape.surfaceArea(5) != 0) {
+            failReason += "Surface area of Line is incorrect!.\n";
+        }
+
+        // Test for circle
+        shape = shapeFactory.getShape(ShapeType.CIRCLE);
+        if (shape.getShapeType() != ShapeType.CIRCLE) {
+            failReason += "Could not create an object for CIRCLE.\n";
+        }
+        if (shape.surfaceArea(9) != 254.46900494077323) {
+            failReason += "Surface area of Circle is incorrect!.\n";
+        }
+
+        // Test for 3-D shape factory
+        // Test for Sphere
+        shapeFactory = FactoryProvider.getShapeFactory(FactoryType.THREE_D_FACTORY);
+        shape = shapeFactory.getShape(ShapeType.SPHERE);
+
+        if (shape.getShapeType() != ShapeType.SPHERE) {
+            failReason += "Could not create and object for SPHERE.\n";
+        }
+        if (shape.surfaceArea(6) != 452.3893421169302) {
+            failReason += "Surface area of Sphere is incorrect!.\n";
+        }
+
+        Assert.assertEquals(failReason, "", failReason);
+
+    }
+}