factory

Factory Design Pattern

• Provides a way to create instance without exposing creation logic.
• A Factory class should have a method which take input and return different instance based on input.
• The return instances should inherit a common interface/class.

Example

A Shape interface inherited by different shapes (here - Rectangle and Circle).

ShapeFactory exposes a factory method getShape which return instances based on ShapeType.

Remarks

• ShapeFactory's getShape is a factory method.

Test

ShapeFactory shapeFactory = new ShapeFactory();

Shape instance1 = shapeFactory.getShape(ShapeType.CIRCLE);
Shape instance2 = shapeFactory.getShape(ShapeType.RECTANGLE);

Assertions.assertInstanceOf(Circle.class, instance1);
Assertions.assertInstanceOf(Rectangle.class, instance2);