Benefits:
• Provides simple interface to a complex system without reducing options provided by the system.
• Increases the reuse of classes by decoupling the interface from the implementation
• Promotes weak coupling between the subsystem and its clients
• Translates client requests to subsystem that can fulfill request

Decorators and Facade evoke similar images in building architecture, but in design pattern
terminology, the Facade is a way of hiding a complex system inside a simpler interface,
whereas Decorator adds function by wrapping a class.

The UML diagram for this pattern is something like this:



This UML diagram shows that, there can be any number of classes involved in this “Facade” system. There is one client, one facade, and multiple classes underneath the facade. In a typical situation, the facade would have a limited amount of actual code, making calls to lower layers most of the time.

public interface Bank {
public Inquiries getInquiry(String
inquiryType); }// End of interface
}// End of interface

The Bank is an interface that only returns Inquiries. The Inquiries are of three types as
discussed before:SavingInquiries, CurrentInquiries and CorporatetInquiries.
All these classes can implement the Inquiries interface. Let’s have a look at the code for one of the Inquiry.

SavingInquiryBank.java

public class SavingInquiryBank implements
Bank { public Inquiries getInquiry ( ) {//
write functionality of saving
accountSavingInquiries savinginquiries = new
SavingInquiries();return savinginquiries;} }//
End of class
Now let’s consider the facade ServiceProvider.