added abstract factory example

src/learn/simple_abstract_factory/AbstractFactory.java

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+package learn.simple_abstract_factory;
+
+public interface AbstractFactory {
+    public AbstractProductA createProductA();
+    public AbstractProductB createProductB();
+}

src/learn/simple_abstract_factory/AbstractProductA.java

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+package learn.simple_abstract_factory;
+
+public interface AbstractProductA {
+}

src/learn/simple_abstract_factory/AbstractProductB.java

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+package learn.simple_abstract_factory;
+
+public interface AbstractProductB {
+}

src/learn/simple_abstract_factory/ConcreteFactory1.java

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+package learn.simple_abstract_factory;
+
+public class ConcreteFactory1 implements AbstractFactory {
+    @Override
+    public AbstractProductA createProductA() {
+        return new ProductA1();
+    }
+
+    @Override
+    public AbstractProductB createProductB() {
+        return new ProductB1();
+    }
+}

src/learn/simple_abstract_factory/ConcreteFactory2.java

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+package learn.simple_abstract_factory;
+
+public class ConcreteFactory2 implements AbstractFactory {
+    @Override
+    public AbstractProductA createProductA() {
+        return new ProductA2();
+    }
+
+    @Override
+    public AbstractProductB createProductB() {
+        return new ProductB2();
+    }
+}

src/learn/simple_abstract_factory/Main.java

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+package learn.simple_abstract_factory;
+
+public class Main {
+    public static void main(String[] args) {
+        Client client1 = new Client(new ConcreteFactory1());
+        Client client2 = new Client(new ConcreteFactory1());
+
+        client1.setup();
+
+        client2.setAbstractFactory(new ConcreteFactory2());
+        client2.setup();
+
+        System.out.println(client1);
+        System.out.println(client2);
+    }
+}

src/learn/simple_abstract_factory/ProductA1.java

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+package learn.simple_abstract_factory;
+
+public class ProductA1 implements AbstractProductA {
+    @Override
+    public String toString() {
+        return "ProductA1";
+    }
+}

src/learn/simple_abstract_factory/ProductA2.java

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+package learn.simple_abstract_factory;
+
+public class ProductA2 implements AbstractProductA {
+    @Override
+    public String toString() {
+        return "ProductA2";
+    }
+}

src/learn/simple_abstract_factory/ProductB1.java

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+package learn.simple_abstract_factory;
+
+public class ProductB1 implements AbstractProductB {
+    @Override
+    public String toString() {
+        return "ProductB1";
+    }
+}

src/learn/simple_abstract_factory/ProductB2.java

@@ -0,0 +1,8 @@
+package learn.simple_abstract_factory;
+
+public class ProductB2 implements AbstractProductB {
+    @Override
+    public String toString() {
+        return "ProductB2";
+    }
+}