Builder Pattern C# with Example

Separate the construction of a complex object from its representation so that the same construction process can 
create different representations and and provides a high level of control over the assembly of the objects. 
In this example demonstrates the Builder pattern in which different vehicles are assembled in a step-by-step 
 

fashion. The Shop uses VehicleBuilders to construct a variety of Vehicles in a series of sequential steps. 
using System; 
using System.Collections.Generic; 
namespace GangOfFour.Builder 
{ 
/// 
 
/// MainApp startup class for Real-World 
/// Builder Design Pattern. 
/// 
 
public class MainApp 
{ 
/// 
 
/// Entry point into console application. 
/// 
 
public static void Main() 
{ 
VehicleBuilder builder; 
// Create shop with vehicle builders 
Shop shop = new Shop(); 
// Construct and display vehicles 
builder = new ScooterBuilder(); 
shop.Construct(builder); 
builder.Vehicle.Show(); 
builder = new CarBuilder(); 
shop.Construct(builder); 
builder.Vehicle.Show(); 
builder = new MotorCycleBuilder(); 
shop.Construct(builder); 
builder.Vehicle.Show(); 
// Wait for user 
Console.ReadKey(); 
} 
} 
/// 
 
/// The 'Director' class 
/// 
 
class Shop 
{ 
// Builder uses a complex series of steps 
public void Construct(VehicleBuilder vehicleBuilder) 
{ 
vehicleBuilder.BuildFrame(); 
vehicleBuilder.BuildEngine(); 
vehicleBuilder.BuildWheels(); 
vehicleBuilder.BuildDoors(); 
} 
} 
/// 
 
/// The 'Builder' abstract class 
/// 
 
abstract class VehicleBuilder 
{ 
protected Vehicle vehicle; 
 

// Gets vehicle instance 
public Vehicle Vehicle 
{ 
get { return vehicle; } 
} 
// Abstract build methods 
public abstract void BuildFrame(); 
public abstract void BuildEngine(); 
public abstract void BuildWheels(); 
public abstract void BuildDoors(); 
} 
/// 
 
/// The 'ConcreteBuilder1' class 
/// 
 
class MotorCycleBuilder : VehicleBuilder 
{ 
public MotorCycleBuilder() 
{ 
vehicle = new Vehicle("MotorCycle"); 
} 
public override void BuildFrame() 
{ 
vehicle["frame"] = "MotorCycle Frame"; 
} 
public override void BuildEngine() 
{ 
vehicle["engine"] = "500 cc"; 
} 
public override void BuildWheels() 
{ 
vehicle["wheels"] = "2"; 
} 
public override void BuildDoors() 
{ 
vehicle["doors"] = "0"; 
} 
} 
/// 
 
/// The 'ConcreteBuilder2' class 
/// 
 
class CarBuilder : VehicleBuilder 
{ 
public CarBuilder() 
{ 
vehicle = new Vehicle("Car"); 
} 
public override void BuildFrame() 
{ 
vehicle["frame"] = "Car Frame"; 
} 
public override void BuildEngine() 
 

{ 
vehicle["engine"] = "2500 cc"; 
} 
public override void BuildWheels() 
{ 
vehicle["wheels"] = "4"; 
} 
public override void BuildDoors() 
{ 
vehicle["doors"] = "4"; 
} 
} 
/// 
 
/// The 'ConcreteBuilder3' class 
/// 
 
class ScooterBuilder : VehicleBuilder 
{ 
public ScooterBuilder() 
{ 
vehicle = new Vehicle("Scooter"); 
} 
public override void BuildFrame() 
{ 
vehicle["frame"] = "Scooter Frame"; 
} 
public override void BuildEngine() 
{ 
vehicle["engine"] = "50 cc"; 
} 
public override void BuildWheels() 
{ 
vehicle["wheels"] = "2"; 
} 
public override void BuildDoors() 
{ 
vehicle["doors"] = "0"; 
} 
} 
/// 
 
/// The 'Product' class 
/// 
 
class Vehicle 
{ 
private string _vehicleType; 
private Dictionary _parts = 
new Dictionary(); 
// Constructor 
public Vehicle(string vehicleType) 
{ 
this._vehicleType = vehicleType; 
} 
// Indexer 
 

public string this[string key] 
{ 
get { return _parts[key]; } 
set { _parts[key] = value; } 
} 
public void Show() 
{ 
Console.WriteLine("\n ------------------------- "); 
Console.WriteLine("Vehicle Type: {0}", _vehicleType); 
Console.WriteLine(" Frame : {0}", _parts["frame"]); 
Console.WriteLine(" Engine : {0}", _parts["engine"]); 
Console.WriteLine(" #Wheels: {0}", _parts["wheels"]); 
Console.WriteLine(" #Doors : {0}", _parts["doors"]); 
} 
} 
} 
Output 
Vehicle Type: Scooter Frame : Scooter Frame 
Engine : none 
#Wheels: 2 
#Doors : 0 
Vehicle Type: Car 
Frame : Car Frame 
Engine : 2500 cc 
#Wheels: 4 
#Doors : 4 
Vehicle Type: MotorCycle 
Frame : MotorCycle Frame 
Engine : 500 cc 
#Wheels: 2 
#Doors : 0