Description
Mediator Pattern is used to reduce the complexity of communication between the objects and is mainly used in enterprise applications. Objects of a system that communicate with each other are known as colleagues. The communication can be done through an interface or abstract class.
Advantages
- Communication can be done easily.
- Relationship can be managed easily.
Conceptual
figure
- Mediator: Mediator is used to define an interface to communicate with Colleague objects.
- ConcreteMediator: ConcreteMediator knows the colleague classes and keeps a reference to the colleague objects.
- Colleague classes: Colleague classes is used to keep a reference to its Mediator object.
Examples
[java]import java.util.*;
public class Room
{
public static void showMessage(User user, String message)//creating a static method
{
System.out.println(new Date().toString() + " [" + user.getName() + "] : " + message);
}
}
public class Person
{
private String name;
public String getPerson()//as the return type expected is String so String datatype is used
{
return name;
}
public void setPerson(String name)//as method doesnot return anything void is used
{
this.name = name;
}
public User(String name)
{
this.name = name;
}
public void sendMessage(String message)
{
ChatRoom.showMessage(this,message);
}
}
public class MediatorPattern
{
public static void main(String[] args)
{
Person robert = new User("John");//creating object for class Person
Person john = new User("Jackson");//creating object for class Person
robert.sendMessage("Hi! John!");
john.sendMessage("Hello! Jackson!");
}
}
[/java]
In the above example-class room, class person is a different classes but communication can be done between them using MediatorPattern class.
Output
The result will be as follows.
[java] Tue Feb 16 16:05:46 IST 2016 [John] : Hi! Jackson!
Tue Feb 16 16:05:46 IST 2016 [Jackson] : Hello! John![/java]
Key Points
- Mediator Pattern - Mediator Pattern makes the communication process easy.
- Mediator Pattern - Loose-coupling between the objects can be done easily.