Facade design pattern example

Façade è Facade pattern hides the complexities of the system and provides an interface to the client using which the client can access the system.

Example : Suppose a customer want to know the availability of a specific maruti car (say AltoK10 or Alto800 or Swift) in a maruti showroom. So he/she simply ask the showroom representative for the availability. Now showroom representative checked the availability and tell the user about available quantity.

Here showroom representative acts a FAÇADE.

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package com.exmpl.facade;

public interface Maruti {

       void getAvailability();

}

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package com.exmpl.facade;

public class AltoK10 implements Maruti {

       @Override

       public void getAvailability() {

              System.out

                           .println("There are FIVE piece of Alto K10 are available in our show room.");

       }

}
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package com.exmpl.facade;

public class Alto800 implements Maruti {

       @Override

       public void getAvailability() {

              System.out

                           .println("There are TWENTY piece of Alto 800 are available in our show room.");

       }

}
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package com.exmpl.facade;

public class Swift implements Maruti {

       @Override

       public void getAvailability() {

              System.out.println("SWIFT is out of stock in our show room.");

       }

}
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// ########### Facade class ###########

package com.exmpl.facade;

public class ShowRoomRepresentative {

       private Maruti altoK10;

       private Maruti alto800;

       private Maruti swift;

       public ShowRoomRepresentative() {

              altoK10 = new AltoK10();

              alto800 = new Alto800();

              swift = new Swift();

       }

       public void checkAltoK10Availability() {

              altoK10.getAvailability();

       }

       public void checkAlto800Availability() {

              alto800.getAvailability();

       }

       public void checkSwiftAvailability() {

              swift.getAvailability();

       }

}
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package com.exmpl.facade;

public class Customer {

       public static void main(String[] args) {

              ShowRoomRepresentative representative = new ShowRoomRepresentative();

              System.out.println("Customer : How many Alto K10 is available?");

              representative.checkAltoK10Availability();

              System.out.println("Customer : How many Alto 800 is available?");

              representative.checkAlto800Availability();

              System.out.println("Customer : How many Swift is available?");

              representative.checkSwiftAvailability();

       }

}
----------------------------------------------------

Output è

Customer : How many Alto K10 is available?

There are FIVE piece of Alto K10 are available in our show room.

Customer : How many Alto 800 is available?

There are TWENTY piece of Alto 800 are available in our show room.

Customer : How many Swift is available?

SWIFT is out of stock in our show room.