The Principle of Least Knowledge

一、//example

public class Car {

    Engine engine;    

     public Car(){}      

   public void start(Key key){

 Doors doors = new Doors();  

//4. parameter

  boolean authorized = key.turns();

 if(authorized){

     //1.component of the object  

    engine.start();  

    //2.the object itself  

    updateDashboardDisplay();  

    //3. new object

     doors.lock();

      }   

  }  

   public void updateDashboardDisplay(){       }

 }

二、Advantages&Disadvantages

Advantages:reduce the dependencies between objects

                 and reduce software maintenance

 Disadvantages:result in more "wrapper" classes being written to handle method calls to other components.

This can result in increased complexity and development time as well as decreased runtime performance.