When to Use the Abstract Factory Pattern

Question

I read about the abstract Factory pattern, but although I understand this, I don't know when to use it. The definition of the template suggests that it is used to abstract the object, but it is not very clear to me, because of why I need to do this, why I should consider the object instance and why (or when) it is important to abstract it.

Answer 1

The main advantage of the template is that it allows you to use clean and reusable code by untying the creation of an object from the use of the object.

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// this is pretty gross, but what can you do
public class SocketFactorySupplier implements Supplier<SSLSocketFactory> {
  @Override public SSLSocketFactory get() {
    if (androidVersion >= 2.1 && androidVersion <= 2.6) {
      return createShiftyWorkaround();
    } else {
      return getDefaultSocketFactory();
    }
  }

  // here are ~500 lines of SSL code
}

...

public class NetworkClient {
  private final Supplier<SSLSocketFactory> supplier;
  private Socket socket;

  public NetworkClient(Supplier<SSLSocketFactory> supplier) {
    this.supplier = supplier;
  }

  public void connect() {
    socket = supplier.get().createSocket();
    socket.connect();

    // code that doesn't care about SSL at all and is simpler for it
  }
}

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Answer 2

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Dim oracleCommand as ICommand = DatabaseManager.GetDatabase("Oracle").CreateCommand

Answer 3

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public class MyShoppingCartUI()
{
    private List<IProduct> _productsInCart = new List<IProduct>();

    public void ClickAddProductButton()
    {
        IProduct product = new ProductOne();
        _productsInCart.Add(product);
    }
}

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public class MyShoppingCartUI()
{
    private List<IProduct> _productsInCart = new List<IProduct>();

    public void ClickAddProductOneButton()
    {
        IProduct product = new ProductOne();
        _productsInCart.Add(product);
    }

    public void ClickAddProductTwoButton()
    {
        IProduct product = new ProductTwo();
        _productsInCart.Add(product);
    }
}

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factory. :

public class ProductFactory()
{
    public IProduct Create(string productName)
    {
        if (productName == "Product1")
            return new ProductOne();
        else if (productName == "Product2")
            return new ProductTwo();            
    }
}

public class MyShoppingCartUI()
{
    private ProductFactory _factory = new ProductFactory();
    private List<IProduct> _productsInCart = new List<IProduct>();

    public void AddItem(string productName)
    {
        IProduct product = _factory.Create(productName);
        _productsInCart.Add(product);
    }
}

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Answer 4

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