Przeglądałem książkę Skuteczna Java i tworzyłem notatki do mojego przyszłego odniesienia, natknąłem się na Wzór Buildera.

Cóż, zrozumiałem, co to jest i jak należy go używać. W tym procesie stworzyłem dwie przykładowe odmiany wzoru budowniczego.

Potrzebowałbym pomocy w spisaniu różnic i korzyści, jakie każdy z nich ma? Cóż, z pewnością to zauważyłemExample 1 eksponuje mniej metod, mniej restrykcyjne i bardziej ogólne, pozwalając na bardziej elastyczne wykorzystanie.

Proszę wskazać inne rzeczy, które przegapiłem?

Przykład 1

package item2;

/**
 * @author Sudhakar Duraiswamy
 *
 */
public  class Vehicle {

    private String type;
    private int wheels;

    interface Builder<T>{
        public  T build();
    }

    public static class CarBuilder implements Builder<Vehicle>{
        private String type;
        private int wheels;     

        CarBuilder createVehicle(){
            this.type= "Car";
            return this;
        }

        CarBuilder addWheels(int wheels){
            this.wheels = wheels;
            return this;
        }

        public Vehicle build(){
            Vehicle v = new Vehicle();
            v.type = type;
            v.wheels = wheels;
            return v;
        }               
    }

    public static class TruckBuilder implements Builder<Vehicle>{       
        private String type;
        private int wheels; 

        TruckBuilder createVehicle(){           
            this.type= "Truck";
            return this;
        }

        TruckBuilder addWheels(int wheels){
            this.wheels = wheels;
            return this;
        }

        public Vehicle build(){
            Vehicle v = new Vehicle();
            v.type = type;
            v.wheels = wheels;
            return v;
        }
    }   

    public Vehicle(){

    }

    public static void main(String[] args) {
        //This builds a car with 4 wheels
        Vehicle car = new Vehicle.CarBuilder().createVehicle().addWheels(4).build();

        //THis builds a Truck with 10 wheels
        Vehicle truck = new Vehicle.TruckBuilder().createVehicle().addWheels(10).build();

    }
}

Przykład 2

package item2;
/**
 * @author Sudhakar Duraiswamy
 *
 */
public  class Vehicle2 {

    private String type;
    private int wheels;

    interface Builder<T>{
        public  T build();      
        public String getType();
        public int getWheels() ;
    }

    public static class CarBuilder implements Builder<Vehicle2>{
        private String type;
        private int wheels;     

        public String getType() {
            return type;
        }
        public int getWheels() {
            return wheels;
        }

        CarBuilder createVehicle(){
            this.type= "Car";
            return this;
        }

        CarBuilder addWheels(int wheels){
            this.wheels = wheels;
            return this;
        }

        public Vehicle2 build(){        
            return new Vehicle2(this);
        }               
    }

    public static class TruckBuilder implements Builder<Vehicle2>{      
        private String type;
        private int wheels; 

        public String getType() {
            return type;
        }

        public int getWheels() {
            return wheels;
        }

        TruckBuilder createVehicle(){           
            this.type= "Truck";
            return this;
        }

        TruckBuilder addWheels(int wheels){
            this.wheels = wheels;
            return this;
        }

        public Vehicle2 build(){
            return new Vehicle2(this);
        }
    }


public Vehicle2(Builder<? extends Vehicle2> builder){
    Vehicle2 v = new Vehicle2();
    v.type = builder.getType();
    v.wheels = builder.getWheels();
}

    public Vehicle2(){
    }

    public static void main(String[] args) {            
        //This builds a car with 4 wheels
        Vehicle2 car = new Vehicle2.CarBuilder().createVehicle().addWheels(4).build();

        //THis builds a Truck with 10 wheels
        Vehicle2 truck = new Vehicle2.TruckBuilder().createVehicle().addWheels(10).build();
    }
}