Design Patterns in Java (Creational) - Mediator Pattern

Mediator Pattern

• Interface based
• Concrete class
• Minimize inheritance
• Knows about his colleges
• Works with the Command Pattern

Main

Mediator

public class Mediator {






 private List<LightReceiver> list = new ArrayList<LightReceiver>();

 

 public void registerLight(LightReceiver lr){

  list.add(lr);

 }

 public void turnOnLights(){

  for (LightReceiver lightReceiver : list) {

   if (!lightReceiver.isOn()) {

    lightReceiver.toogle();

   }

  }

 }

}

Command

public interface Command {



 public void execute();

}

Command Implemented

public class TurnOnAllLightsCommand implements Command {

 Mediator m;

 

 public TurnOnAllLightsCommand(Mediator m){

  this.m = m;

 }

 

 

 @Override

 public void execute() {

  m.turnOnLights();

 }

}

Receiver

public class LightReceiver {




 private boolean isOn = false;

 public boolean isOn(){

  return isOn;

 }

 

 public void on(){

  System.out.println("Light is on");

 }

 public void off(){

  System.out.println("Light is off");

 }

 public void toogle(){

  if(isOn)

   off();

  else

   on();

  isOn = !isOn;

 }

}