Factory design pattern

The Java factory pattern is based on polymorphic method call of type inheritance to create instance of the appropriate type. The purpose of using the factory pattern is to provide user a common user interface across a group of sub types that share a common super type. Following sample code is an implementation of the factory pattern.

//super class can be an interface or abstract class
public class CarFactory {
      public Car createCar() {
            return new Car();
      }
}

public class SportCarFactory extends CarFactory {
      public Car createCar() {
            return new SportCar();
      }
}

public class SedanCarFactory extends CarFactory {
      public Car createCar() {
            return new SedanCar();
      }
}

//call factory.createCar() will automatically create the proper type of car
public class CarShop {
      private CarFactory factory;

      public Car createSportCar() {
            factory = new SportCarFactory();
            factory.createCar();
      }

      public Car createSedanCar() {
            factory = new SedanCarFactory();
            facotry.createCar();
      }
}

References:
1. Factory method pattern

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