Factory Design Patterns Tutorial313

Factory design patterns are creational design patterns that provide an interface for creating objects but allow subclasses to alter the type of objects that will be created. This is useful when you want to create a family of related objects without having to specify the exact class of the object that will be created.

There are three main types of factory design patterns:
Simple Factory: This is the simplest type of factory pattern. It creates objects by calling a static method on a factory class. The factory class is responsible for creating and returning the correct type of object.
Factory Method: This pattern is similar to the simple factory pattern, but it allows subclasses to define the type of objects that will be created. This gives subclasses more control over the object creation process.
Abstract Factory: This pattern is used to create families of related objects. It provides an interface for creating a set of related objects, but it allows subclasses to define the actual type of objects that will be created.

Factory design patterns can be used in a variety of situations. Here are a few examples:
Creating a family of related objects: Factory design patterns can be used to create families of related objects, such as a family of shapes or a family of widgets. This makes it easy to create and manage a group of related objects.
Encapsulating object creation: Factory design patterns can be used to encapsulate the object creation process. This can make it easier to change the way that objects are created without affecting the rest of the application.
Providing a consistent interface for object creation: Factory design patterns can be used to provide a consistent interface for object creation. This can make it easier to create objects in a variety of situations.

Factory design patterns are a powerful tool that can be used to improve the design of your applications. They can make it easier to create, manage, and change objects.## Simple Factory Pattern

The simple factory pattern is the simplest type of factory pattern. It creates objects by calling a static method on a factory class. The factory class is responsible for creating and returning the correct type of object.

Here is an example of a simple factory pattern:```java
public class ShapeFactory {
public static Shape createShape(String shapeType) {
if (("circle")) {
return new Circle();
} else if (("square")) {
return new Square();
} else if (("rectangle")) {
return new Rectangle();
} else {
throw new IllegalArgumentException("Invalid shape type: " + shapeType);
}
}
}
```

This factory class can be used to create any type of shape. To create a circle, you would call the `createShape` method and pass in the string "circle". The factory class would then create and return a new `Circle` object.## Factory Method Pattern

The factory method pattern is similar to the simple factory pattern, but it allows subclasses to define the type of objects that will be created. This gives subclasses more control over the object creation process.

Here is an example of a factory method pattern:```java
public abstract class ShapeFactory {
public abstract Shape createShape();
}
public class CircleFactory extends ShapeFactory {
@Override
public Shape createShape() {
return new Circle();
}
}
public class SquareFactory extends ShapeFactory {
@Override
public Shape createShape() {
return new Square();
}
}
public class RectangleFactory extends ShapeFactory {
@Override
public Shape createShape() {
return new Rectangle();
}
}
```

To create a circle, you would create a `CircleFactory` object and call the `createShape` method. The `CircleFactory` object would then create and return a new `Circle` object.## Abstract Factory Pattern

The abstract factory pattern is used to create families of related objects. It provides an interface for creating a set of related objects, but it allows subclasses to define the actual type of objects that will be created.

Here is an example of an abstract factory pattern:```java
public interface ShapeFactory {
Shape createShape(String shapeType);
}
public class CircleFactory implements ShapeFactory {
@Override
public Shape createShape(String shapeType) {
if (("circle")) {
return new Circle();
} else {
throw new IllegalArgumentException("Invalid shape type: " + shapeType);
}
}
}
public class SquareFactory implements ShapeFactory {
@Override
public Shape createShape(String shapeType) {
if (("square")) {