Builder Design Pattern

Builder Design Pattern
Advantage of Builder DP
Usage of Builder DP
UML of Builder DP
Example of Builder DP

Builder Pattern says that “construct a complex object from simple objects using step-by-step approach”

It is mostly used when object can’t be created in single step like in the de-serialization of a complex object.

Advantage of Builder Design Pattern

The main advantages of Builder Pattern are as follows:

It provides clear separation between the construction and representation of an object.
It provides better control over construction process.
It supports to change the internal representation of objects.

UML for Builder Pattern Example

Builder Design Pattern

Example of Builder Design Pattern

To create simple example of builder design pattern, you need to follow 6 following steps.

Create Packing interface
Create 2 abstract classes CD and Company
Create 2 implementation classes of Company: Sony and Samsung
Create the CDType class
Create the CDBuilder class
Create the BuilderDemo class

1) Create Packing interface

File: Packing.java

 public interface Packing {             public String pack();             public int price(); } 

2) Create 2 abstract classes CD and Company

Create an abstract class CD which will implement Packing interface.

File: CD.java

File: Company.java

3) Create 2 implementation classes of Company: Sony and Samsung

File: Sony.java

 public class Sony extends Company{ @Override         public int price(){                          return 20;   } @Override public String pack(){          return “Sony CD”;      } }//End of the Sony class. 

File: Samsung.java

 public class Samsung extends Company { @Override         public int price(){                          return 15; } @Override public String pack(){          return “Samsung CD”;         } }//End of the Samsung class. 

4) Create the CDType class

File: CDType.java

 import java.util.ArrayList; import java.util.List; public class CDType {              private List<Packing> items=new ArrayList<Packing>();              public void addItem(Packing packs) {                       items.add(packs);              }              public void getCost(){               for (Packing packs : items) {                         packs.price();               }              }              public void showItems(){               for (Packing packing : items){          System.out.print(“CD name : “+packing.pack());          System.out.println(“, Price : “+packing.price());       }             } }//End of the CDType class. 

5) Create the CDBuilder class

File: CDBuilder.java

 public class CDBuilder {                   public CDType buildSonyCD(){                       CDType cds=new CDType();                      cds.addItem(new Sony());                      return cds;           }           public CDType buildSamsungCD(){      CDType cds=new CDType();      cds.addItem(new Samsung());      return cds;           } }// End of the CDBuilder class. 

6) Create the BuilderDemo class

File: BuilderDemo.java

 public class BuilderDemo{  public static void main(String args[]){    CDBuilder cdBuilder=new CDBuilder();    CDType cdType1=cdBuilder.buildSonyCD();    cdType1.showItems();     CDType cdType2=cdBuilder.buildSamsungCD();    cdType2.showItems();  } } 

download this builder pattern example

Output of the above example

Another Real world example of Builder Pattern

UML for Builder Pattern:

We are considering a business case of pizza-hut where we can get different varieties of pizza and cold-drink.

Pizza can be either a Veg pizza or Non-Veg pizza of several types (like cheese pizza, onion pizza, masala-pizza etc) and will be of 4 sizes i.e. small, medium, large, extra-large.

Cold-drink can be of several types (like Pepsi, Coke, Dew, Sprite, Fanta, Maaza, Limca, Thums-up etc.) and will be of 3 sizes small, medium, large.

Builder Design Pattern uml

Real world example of builder pattern

Let’s see the step by step real world example of Builder Design Pattern.

Step 1:Create an interface Item that represents the Pizza and Cold-drink.

File: Item.java

 public  interface  Item  {    public String name();     public String size();     public float price(); }// End of the interface Item.  

Step 2:Create an abstract class Pizza that will implement to the interface Item.

File: Pizza.java

 public abstract class Pizza implements Item{         @Override         public abstract float price(); }  

Step 3:Create an abstract class ColdDrink that will implement to the interface Item.

File: ColdDrink.java

        public abstract class ColdDrink implements Item{         @Override         public abstract float price();    }  

Step 4:Create an abstract class VegPizza that will extend to the abstract class Pizza.

File: VegPizza.java

 public abstract class VegPizza extends Pizza{     @Override     public abstract float price();     @Override     public abstract  String name();     @Override     public abstract  String size(); }// End of the abstract class VegPizza. 

Step 5:Create an abstract class NonVegPizza that will extend to the abstract class Pizza.

File: NonVegPizza.java

 public abstract class NonVegPizza extends Pizza{     @Override     public abstract float price();     @Override     public abstract String name();     @Override     public abstract String size(); }// End of the abstract class NonVegPizza. 

Step 6:Now, create concrete sub-classes SmallCheezePizza, MediumCheezePizza, LargeCheezePizza, ExtraLargeCheezePizza that will extend to the abstract class VegPizza.

File: SmallCheezePizza.java

 public class SmallCheezePizza extends VegPizza{     @Override     public float price() {         return 170.0f;     }     @Override     public String name() {         return “Cheeze Pizza”;     }     @Override     public String size() {        return “Small size”;     }   }// End of the SmallCheezePizza class. 

File: MediumCheezePizza.java

 public class MediumCheezePizza extends VegPizza{     @Override     public float price() {        return  220.f;     }     @Override     public String name() {         return “Cheeze Pizza”;     }     @Override     public String size() {      return “Medium Size”;  } }// End of the MediumCheezePizza class. 

File: LargeCheezePizza.java

 public class LargeCheezePizza extends VegPizza{     @Override     public float price() {         return 260.0f;     }     @Override     public String name() {         return “Cheeze Pizza”;     }     @Override     public String size() {         return “Large Size”;     } }// End of the LargeCheezePizza class. 

File: ExtraLargeCheezePizza.java

 public class ExtraLargeCheezePizza extends VegPizza{     @Override     public float price() {         return 300.f;     }     @Override     public String name() {         return  “Cheeze Pizza”;     }     @Override     public String size() {         return “Extra-Large Size”;     } }// End of the ExtraLargeCheezePizza class. 

Step 7:Now, similarly create concrete sub-classes SmallOnionPizza, MediumOnionPizza, LargeOnionPizza, ExtraLargeOnionPizza that will extend to the abstract class VegPizza.

File: SmallOnionPizza.java

 public class SmallOnionPizza extends VegPizza {     @Override     public float price() {         return 120.0f;     }     @Override     public String name() {         return  “Onion Pizza”;     }     @Override     public String size() {        return  “Small Size”;     }   }// End of the SmallOnionPizza class. 

File: MediumOnionPizza.java

 public class MediumOnionPizza extends VegPizza {     @Override     public float price() {         return 150.0f;     }    @Override     public String name() {         return  “Onion Pizza”;     }    @Override     public String size() {        return  “Medium Size”;     }   }// End of the MediumOnionPizza class. 

File: LargeOnionPizza.java

 public class LargeOnionPizza extends  VegPizza{     @Override     public float price() {         return 180.0f;     }     @Override     public String name() {          return “Onion Pizza”;     }     @Override     public String size() {        return  “Large size”;     } }// End of the LargeOnionPizza class. 

File: ExtraLargeOnionPizza.java

 public class ExtraLargeOnionPizza extends VegPizza {     @Override     public float price() {         return 200.0f;     }     @Override     public String name() {          return  “Onion Pizza”;     }     @Override     public String size() {        return  “Extra-Large Size”;     } }// End of the ExtraLargeOnionPizza class 

Step 8:Now, similarly create concrete sub-classes SmallMasalaPizza, MediumMasalaPizza, LargeMasalaPizza, ExtraLargeMasalaPizza that will extend to the abstract class VegPizza.

File: SmallMasalaPizza.java

 public class SmallMasalaPizza extends VegPizza{     @Override     public float price() {         return 100.0f;     }     @Override     public String name() {         return  “Masala Pizza”;     }     @Override     public String size() {        return  “Samll Size”;     } }// End of the SmallMasalaPizza class 

File: MediumMasalaPizza.java

 public class MediumMasalaPizza extends VegPizza {          @Override     public float price() {         return 120.0f;     }      @Override     public String name() {              return  “Masala Pizza”;          }      @Override     public String size() {        return  “Medium Size”;     }  

File: LargeMasalaPizza.java

 public class LargeMasalaPizza extends  VegPizza{     @Override     public float price() {         return 150.0f;     }      @Override     public String name() {              return  “Masala Pizza”;          }      @Override     public String size() {        return  “Large Size”;     } } //End of the LargeMasalaPizza class  

File: ExtraLargeMasalaPizza.java

 public class ExtraLargeMasalaPizza extends VegPizza {     @Override     public float price() {         return 180.0f;     }      @Override     public String name() {              return  “Masala Pizza”;          }      @Override     public String size() {        return  “Extra-Large Size”;     } }// End of the ExtraLargeMasalaPizza class   

Step 9:Now, create concrete sub-classes SmallNonVegPizza, MediumNonVegPizza, LargeNonVegPizza, ExtraLargeNonVegPizza that will extend to the abstract class NonVegPizza.

File: SmallNonVegPizza.java

 public class SmallNonVegPizza extends NonVegPizza {      @Override     public float price() {         return 180.0f;     }      @Override     public String name() {        return “Non-Veg Pizza”;     }      @Override     public String size() {         return “Samll Size”;     }      }// End of the SmallNonVegPizza class  

File: MediumNonVegPizza.java

 public class MediumNonVegPizza extends NonVegPizza{          @Override     public float price() {         return 200.0f;     }      @Override     public String name() {        return “Non-Veg Pizza”;     }      @Override     public String size() {         return “Medium Size”;     }  

File: LargeNonVegPizza.java

 public class LargeNonVegPizza extends NonVegPizza{          @Override     public float price() {         return 220.0f;     }      @Override     public String name() {        return “Non-Veg Pizza”;     }      @Override     public String size() {         return “Large Size”;     }      }// End of the LargeNonVegPizza class  

File: ExtraLargeNonVegPizza.java

 public class ExtraLargeNonVegPizza extends NonVegPizza {     @Override     public float price() {         return 250.0f;     }      @Override     public String name() {        return “Non-Veg Pizza”;     }      @Override     public String size() {         return “Extra-Large Size”;     }      }   // End of the ExtraLargeNonVegPizza class  

Step 10:Now, create two abstract classes Pepsi and Coke that will extend abstract class ColdDrink.

File: Pepsi.java

 public abstract class Pepsi extends ColdDrink {      @Override     public abstract  String name();      @Override     public abstract  String size();          @Override     public abstract  float price();       }// End of the Pepsi class  

File: Coke.java

 public abstract class Coke  extends ColdDrink {      @Override     public abstract  String name();      @Override     public abstract  String size();          @Override     public abstract  float price();       }// End of the Coke class  

Step 11:Now, create concrete sub-classes SmallPepsi, MediumPepsi, LargePepsi that will extend to the abstract class Pepsi.

File: SmallPepsi.java

 public class SmallPepsi  extends Pepsi{      @Override     public String name() {        return “300 ml Pepsi”;     }      @Override     public float price() {         return 25.0f;     }      @Override     public String size() {         return “Small Size”;     }    }// End of the SmallPepsi class  

File: MediumPepsi.java

 public class MediumPepsi extends Pepsi {          @Override     public String name() {        return “500 ml Pepsi”;     }      @Override     public String size() {         return “Medium Size”;     }      @Override     public float price() {         return 35.0f;     }     }// End of the MediumPepsi class  

File: LargePepsi.java

 public class LargePepsi extends Pepsi{     @Override     public String name() {        return “750 ml Pepsi”;     }      @Override     public String size() {         return “Large Size”;     }      @Override     public float price() {         return 50.0f;     } }// End of the LargePepsi class  

Step 12:Now, create concrete sub-classes SmallCoke, MediumCoke, LargeCoke that will extend to the abstract class Coke.

File: SmallCoke.java

 public class SmallCoke extends Coke{         @Override     public String name() {          return “300 ml Coke”;       }      @Override     public String size() {                 return “Small Size”;     }      @Override     public float price() {              return  25.0f;     }  }// End of the SmallCoke class  

File: MediumCoke.java

 public class MediumCoke extends Coke{          @Override     public String name() {          return “500 ml Coke”;       }      @Override     public String size() {                 return “Medium Size”;     }      @Override     public float price() {              return  35.0f;    } }// End of the MediumCoke class  

File: LargeCoke.java

 public class LargeCoke extends Coke {      @Override     public String name() {          return “750 ml Coke”;       }      @Override     public String size() {                 return “Large Size”;     }      @Override     public float price() {              return  50.0f;     }     }// End of the LargeCoke class  

Step 13:Create an OrderedItems class that are having Item objects defined above.

File: OrderedItems.java

 import java.util.ArrayList; import java.util.List; public class OrderedItems {         List<Item> items=new ArrayList<Item>();          public void addItems(Item item){                  items.add(item);     }     public float getCost(){                  float cost=0.0f;             for (Item item : items) {                 cost+=item.price();              }         return cost;     }     public void showItems(){                  for (Item item : items) {             System.out.println(“Item is:” +item.name());             System.out.println(“Size is:” +item.size());             System.out.println(“Price is: ” +item.price());                      }     }     }// End of the OrderedItems class  

Step 14:Create an OrderBuilder class that will be responsible to create the objects of OrderedItems class.

File: OrdereBuilder.java

 import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class OrderBuilder {     public OrderedItems preparePizza() throws IOException{                  OrderedItems itemsOrder=new OrderedItems();          BufferedReader br =new BufferedReader(new InputStreamReader(System.in));                  System.out.println(” Enter the choice of Pizza “);         System.out.println(“============================”);         System.out.println(”        1. Veg-Pizza       “);         System.out.println(”        2. Non-Veg Pizza   “);         System.out.println(”        3. Exit            “);         System.out.println(“============================”);                  int pizzaandcolddrinkchoice=Integer.parseInt(br.readLine());         switch(pizzaandcolddrinkchoice)         {            case 1:{                                            System.out.println(“You ordered Veg Pizza”);                      System.out.println(“nn”);                      System.out.println(” Enter the types of Veg-Pizza “);                      System.out.println(“——————————“);                      System.out.println(”        1.Cheeze Pizza        “);                      System.out.println(”        2.Onion Pizza        “);                      System.out.println(”        3.Masala Pizza        “);                      System.out.println(”        4.Exit            “);                      System.out.println(“——————————“);                                   int vegpizzachoice=Integer.parseInt(br.readLine());                      switch(vegpizzachoice)                      {                           case 1:                                 {                                     System.out.println(“You ordered Cheeze Pizza”);                                                                          System.out.println(“Enter the cheeze pizza size”);                                     System.out.println(“————————————“);                                     System.out.println(”    1. Small Cheeze Pizza “);                                     System.out.println(”    2. Medium Cheeze Pizza “);                                     System.out.println(”    3. Large Cheeze Pizza “);                                     System.out.println(”    4. Extra-Large Cheeze Pizza “);                                     System.out.println(“————————————“);                                     int cheezepizzasize=Integer.parseInt(br.readLine());                                     switch(cheezepizzasize)                                         {                                               case 1:                                                    itemsOrder.addItems(new SmallCheezePizza());                                                    break;                                              case 2:                                                    itemsOrder.addItems(new MediumCheezePizza());                                                    break;                                                case 3:                                                    itemsOrder.addItems(new LargeCheezePizza());                                                    break;                                                case 4:                                                    itemsOrder.addItems(new ExtraLargeCheezePizza());                                                    break;                               case 2:                                 {                                     System.out.println(“You ordered Onion Pizza”);                                     System.out.println(“Enter the Onion pizza size”);                                     System.out.println(“———————————-“);                                     System.out.println(”    1. Small Onion Pizza “);                                     System.out.println(”    2. Medium Onion Pizza “);                                     System.out.println(”    3. Large Onion Pizza “);                                     System.out.println(”    4. Extra-Large Onion Pizza “);                                     System.out.println(“———————————-“);                                     int onionpizzasize=Integer.parseInt(br.readLine());                                     switch(onionpizzasize)                                               {                                                   case 1:                                                    itemsOrder.addItems(new SmallOnionPizza());                                                    break;                                                                                                        case 2:                                                    itemsOrder.addItems(new MediumOnionPizza());                                                    break;                                                                                                         case 3:                                                    itemsOrder.addItems(new LargeOnionPizza());                                                    break;                                                                                                            case 4:                                                    itemsOrder.addItems(new ExtraLargeOnionPizza());                                                    break;                                                                                                            }                                         }                                 break;                           case 3:                                 {                                     System.out.println(“You ordered Masala Pizza”);                                     System.out.println(“Enter the Masala pizza size”);                                     System.out.println(“————————————“);                                     System.out.println(”    1. Small Masala Pizza “);                                     System.out.println(”    2. Medium Masala Pizza “);                                      System.out.println(”    3. Large Masala Pizza “);                                     System.out.println(”    4. Extra-Large Masala Pizza “);                                     System.out.println(“————————————“);                                                   int masalapizzasize=Integer.parseInt(br.readLine());                                         switch(masalapizzasize)                                               {                                                   case 1:                                                    itemsOrder.addItems(new SmallMasalaPizza());                                                    break;                                                                                                        case 2:                                                    itemsOrder.addItems(new MediumMasalaPizza());                                                    break;                                                                                                         case 3:                                                    itemsOrder.addItems(new LargeMasalaPizza());                                                    break;                                                                                                            case 4:                                                    itemsOrder.addItems(new ExtraLargeMasalaPizza());                                                    break;                                                                                                            }                                                                        }                                 break;                                                    }                                         }                    break;// Veg- pizza choice completed.                              case 2:                    {                        System.out.println(“You ordered Non-Veg Pizza”);                        System.out.println(“nn”);                                                             System.out.println(“Enter the Non-Veg pizza size”);                                     System.out.println(“————————————“);                                     System.out.println(”    1. Small Non-Veg  Pizza “);                                     System.out.println(”    2. Medium Non-Veg  Pizza “);                                     System.out.println(”    3. Large Non-Veg  Pizza “);                                     System.out.println(”    4. Extra-Large Non-Veg  Pizza “);                                     System.out.println(“————————————“);                                                                                     int nonvegpizzasize=Integer.parseInt(br.readLine());                                                 switch(nonvegpizzasize)                              {                                                                   case 1:                                       itemsOrder.addItems(new SmallNonVegPizza());                                       break;                                                                                        case 2:                                       itemsOrder.addItems(new MediumNonVegPizza());                                       break;                                                                                         case 3:                                       itemsOrder.addItems(new LargeNonVegPizza());                                       break;                                                                                            case 4:                                       itemsOrder.addItems(new ExtraLargeNonVegPizza());                                       break;                                     }                                                             }                           break;             default:             {                   break;                              }                   }//end of main Switch                      //continued?..         System.out.println(” Enter the choice of ColdDrink “);         System.out.println(“============================”);         System.out.println(”        1. Pepsi            “);         System.out.println(”        2. Coke             “);         System.out.println(”        3. Exit             “);         System.out.println(“============================”);                       int coldDrink=Integer.parseInt(br.readLine());         switch (coldDrink)              {                case 1:                                 {                                     System.out.println(“You ordered Pepsi “);                                     System.out.println(“Enter the  Pepsi Size “);                                     System.out.println(“————————“);                                     System.out.println(”    1. Small Pepsi “);                                     System.out.println(”    2. Medium Pepsi “);                                     System.out.println(”    3. Large Pepsi “);                                     System.out.println(“————————“);                                               int pepsisize=Integer.parseInt(br.readLine());                                     switch(pepsisize)                                               {                                                   case 1:                                                    itemsOrder.addItems(new SmallPepsi());                                                    break;                                                                                                        case 2:                                                    itemsOrder.addItems(new MediumPepsi());                                                    break;                                                                                                         case 3:                                                    itemsOrder.addItems(new LargePepsi());                                                    break;                                                                                                          }                                  }                                   break;                          case 2:                                 {                                     System.out.println(“You ordered Coke”);                                     System.out.println(“Enter the Coke Size”);                                     System.out.println(“————————“);                                     System.out.println(”    1. Small Coke “);                                     System.out.println(”    2. Medium Coke  “);                                     System.out.println(”    3. Large Coke  “);                                     System.out.println(”    4. Extra-Large Coke “);                                     System.out.println(“————————“);                                                                          int cokesize=Integer.parseInt(br.readLine());                                     switch(cokesize)                                               {                                                   case 1:                                                    itemsOrder.addItems(new SmallCoke());                                                    break;                                                                                                        case 2:                                                    itemsOrder.addItems(new MediumCoke());                                                    break;                                                                                                         case 3:                                                    itemsOrder.addItems(new LargeCoke());                                                    break;                                                                                                                                                           }                                                                        }                                 break;                      default:                                       {                                                    break;                                                        }                                                                  }//End of the Cold-Drink switch                   return itemsOrder;            } //End of the preparePizza() method   

Step 15:Create a BuilderDemo class that will use the OrderBuilder class.

File: Prototype.java

 import java.io.IOException; public class BuilderDemo {      public static void main(String[] args) throws IOException {         // TODO code application logic here                  OrderBuilder builder=new OrderBuilder();                  OrderedItems orderedItems=builder.preparePizza();                  orderedItems.showItems();                  System.out.println(“n”);         System.out.println(“Total Cost : “+ orderedItems.getCost());              } }// End of the BuilderDemo class   

download this Builder Pattern Example

Output

builderDesign Pattern output 1 builder Design Pattern output 1

Next TopicObject Pool Pattern

Builder Design Pattern

Builder Design Pattern

Advantage of Builder Design Pattern

UML for Builder Pattern Example

Example of Builder Design Pattern

1) Create Packing interface

2) Create 2 abstract classes CD and Company

3) Create 2 implementation classes of Company: Sony and Samsung

4) Create the CDType class

5) Create the CDBuilder class

6) Create the BuilderDemo class

Output of the above example

Another Real world example of Builder Pattern

UML for Builder Pattern:

Real world example of builder pattern

Output

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