A Hotel needs to reduce the overall power used by the equipments installed in its many floors. So the Hotel Management has installed sensors, like Motion Sensors, etc at appropriate places .I have to design a controller which takes inputs from these sensors and controls the various equipments.

1. A Hotel can have multiple floors


2. Each floor can have multiple main corridors and sub corridors


3. Both main corridor and sub corridor have one light each


4. Both main and sub corridor lights consume 5 units of power when ON


5. Both main and sub corridor have independently controllable ACs


6. Both main and sub corridor ACs consume 10 units of power when ON


7. All the lights in all the main corridors need to be switched ON


8. When a motion is detected in one of the sub corridors the
   corresponding lights need to be switched ON


9. When there is no motion for more than a minute the sub corridor
   lights should be switched OFF


10. The total power consumption of all the ACs and lights combined
    should not exceed (Number of Main corridors * 15) + (Number of sub
    corridors * 10) units of ​ per floor. Sub corridor AC could be
    switched OFF to ensure that the power consumption is not more than
    the specified maximum value


11. When the power consumption goes below the specified maximum value
    the ACs that were switched OFF previously must be switched ON

I am writing the Controller program that takes input values for Floors, Main corridors, Sub corridors and takes
different external inputs for motion in sub corridors and for each input prints out the state of all
the lights and ACs in the hotel.

So starting with Modelling the hotel part by parts.

public abstract class Equipment 

 private String id;

 private boolean isON;

 Equipment(String id) 
 this.id = id;
 

 public boolean isON() 
 return isON;
 

 public void switchON() 
 isON = true;
 

 public void switchOFF() 
 isON = false;
 

 public void printStatus() 
 String status = isON() ? "ON" : "OFF";
 System.out.println("tt" + id + " " + status);
 

 abstract public int getPowerConsumption();

public class Light extends Equipment 

 public static int SPECPOWER = 5;

 public Light(String id) 
 super(id);
 

 @Override
 public int getPowerConsumption() 
 return isON() ? 5 : 0;
 

public class AirConditioner extends Equipment 

 public static int SPECPOWER = 10;

 public AirConditioner(String id) 
 super(id);
 

 @Override
 public int getPowerConsumption() 
 return isON() ? 10 : 0;
 

public abstract class Corridor 

 private String id;

 private List<Light> lights;

 private List<AirConditioner> airConditioners;

 public Corridor(String id, List<Light> lights, List<AirConditioner> airConditioners) 
 this.id = id;
 this.lights = lights;
 this.airConditioners = airConditioners;
 

 public List<Light> getLights() 
 return lights;
 

 public List<AirConditioner> getAirConditioners() 
 return airConditioners;
 

 public int getTotalPowerConsumption() 

 int result = 0;

 for (Light light : lights)
 result += light.getPowerConsumption();

 for (AirConditioner airConditioner : airConditioners)
 result += airConditioner.getPowerConsumption();

 return result;
 

 public void printStatus() 

 System.out.println("t" + id);
 for (Light light : lights) 
 light.printStatus();
 
 for (AirConditioner airConditioner : airConditioners) 
 airConditioner.printStatus();
 
 

public class MainCorridor extends Corridor 

 public MainCorridor(String id, List<Light> lights, List<AirConditioner> airConditioners) 
 super(id, lights, airConditioners);
 

public class SubCorridor extends Corridor 

 public SubCorridor(String id, List<Light> lights, List<AirConditioner> airConditioners) 
 super(id, lights, airConditioners);
 

 public List<AirConditioner> getONAirConditioners() 

 List<AirConditioner> result = new ArrayList<>();

 for (AirConditioner airConditioner : getAirConditioners()) 
 if(airConditioner.isON())
 result.add(airConditioner);
 

 return result;
 

 public void motionDetected() 
 for (Light light : getLights())
 light.switchON();
 

 public void clearMotionEvent() 
 for (Light light : getLights())
 light.switchOFF();
 

public class Floor 

 private String id;

 private Map<String, MainCorridor> mainCorridorMap;

 private Map<String, SubCorridor> subCorridorMap;

 private Queue<AirConditioner> switchedOFFACs = new LinkedList<>();

 public Floor(String id, Map<String, MainCorridor> mainCorridorMap, Map<String, SubCorridor> subCorridorMap) 
 this.id = id;
 this.mainCorridorMap = mainCorridorMap;
 this.subCorridorMap = subCorridorMap;
 

 public void motionDetected(String corridorId) 

 SubCorridor subCorridor = subCorridorMap.get(corridorId);

 subCorridor.motionDetected();

 int totalPower = getTotalPower();

 int maxPower = getMaxPower();

 if (totalPower > maxPower) 

 int excessPowerConsumed = totalPower - maxPower;

 int numberOfACstoBeSwitchedOFF = (int) Math.round((double) excessPowerConsumed / (double) AirConditioner.SPECPOWER);

 switchOFFAC(corridorId, numberOfACstoBeSwitchedOFF);
 
 

 public void clearMotionEvent(String corridorId) 

 SubCorridor subCorridor = subCorridorMap.get(corridorId);

 subCorridor.clearMotionEvent();

 int totalPower = getTotalPower();

 int maxPower = getMaxPower();

 if (totalPower < maxPower) 
 int powerAvailableToUse = maxPower - totalPower;

 int noOfAcsToTurnOn = (int) Math.floor((double) powerAvailableToUse / (double) AirConditioner.SPECPOWER);

 switchONACs(noOfAcsToTurnOn);
 
 

 private void switchONACs(int noOfAcsToTurnOn) 

 for (int i = 0; i < noOfAcsToTurnOn; i++) 
 AirConditioner airConditioner = switchedOFFACs.remove();
 airConditioner.switchON();
 
 

 private void switchOFFAC(String corridorId, int numberOfACstoBeSwitchedOFF) 

 for (String id : subCorridorMap.keySet()) 

 if (id.equals(corridorId))
 continue;

 SubCorridor subCorridor = subCorridorMap.get(id);

 List<AirConditioner> onAirConditioners = subCorridor.getONAirConditioners();

 for (AirConditioner onAirConditioner : onAirConditioners) 
 onAirConditioner.switchOFF();
 switchedOFFACs.add(onAirConditioner);
 numberOfACstoBeSwitchedOFF--;
 

 if (numberOfACstoBeSwitchedOFF == 0)
 return;
 
 

 private int getTotalPower() 

 int result = 0;

 for (MainCorridor mainCorridor : mainCorridorMap.values())
 result += mainCorridor.getTotalPowerConsumption();

 for (SubCorridor subCorridor : subCorridorMap.values())
 result += subCorridor.getTotalPowerConsumption();

 return result;
 

 private int getMaxPower() 
 return (mainCorridorMap.size() * 15) + (subCorridorMap.size() * 10);
 

 public void printStatus() 

 System.out.println(id);
 System.out.println();

 for (MainCorridor mainCorridor : mainCorridorMap.values()) 
 mainCorridor.printStatus();
 System.out.println();
 

 for (SubCorridor subCorridor : subCorridorMap.values()) 
 subCorridor.printStatus();
 System.out.println();
 
 

public class Hotel 

 private String name;

 private Map<String,Floor> floorMap;

 public Hotel(String name, Map<String, Floor> floorMap) 
 this.name = name;
 this.floorMap = floorMap;
 

 public void cleanFloor(Address address) 
 Floor floor = floorMap.get(address.getFloorId());

 floor.clearMotionEvent(address.getCorridorId());
 

 public void motionDetected(Address address) 

 Floor floor = floorMap.get(address.getFloorId());

 floor.motionDetected(address.getCorridorId());
 

 public void printStatus() 

 System.out.println("Power status of Equipments in Hotel " + name);

 for (String floorId : floorMap.keySet()) 

 Floor floor = floorMap.get(floorId);

 floor.printStatus();
 
 

The interface for external input which is the motion event in corridors.

public interface Listener 
 void eventOccurred(String floorId, String subCorridorId);

public class MotionListener implements Listener 

 private IController controller;

 public MotionListener(IController controller) 
 this.controller = controller;
 

 @Override
 public void eventOccurred(String floorId, String subCorridorId) 
 Address address = new Address(floorId, subCorridorId);

 controller.actOnMotionEvent(address);
 

public class Address 

 private String floorId;
 private String corridorId;

 public Address(String floorId, String corridorId) 
 this.floorId = floorId;
 this.corridorId = corridorId;
 

 public String getFloorId() 
 return floorId;
 

 public String getCorridorId() 
 return corridorId;
 

 @Override
 public boolean equals(Object o) 

 @Override
 public int hashCode() 
 int result = floorId.hashCode();
 result = 31 * result + corridorId.hashCode();
 return result;
 

And the Controller which does the buisiness logic.

public interface IController 
 void actOnMotionEvent(Address address);

 void destroyMotionWatcher(Address address);

 void printStatus();

public class Controller implements IController 

 private Hotel hotel;

 private Map<Address, MotionWatcher> motionWatcherMap = new HashMap<>();

 public Controller(int floorCount, int mainCorridorsCount, int subCorridorsCount) 

 Map<String, Floor> floorMap = createFloorMap(floorCount, mainCorridorsCount, subCorridorsCount);

 this.hotel = new Hotel("MyHotel", floorMap);
 

 private Map<String, Floor> createFloorMap(int floorCount, int mainCorridors, int subCorridors) 

 Map<String, SubCorridor> subCorridorMap = getSubCorridorMap(subCorridors);

 Map<String, MainCorridor> mainCorridorMap = getMainCorridorMap(mainCorridors);

 return getFloorMap(floorCount, mainCorridorMap, subCorridorMap);
 

 private Map<String, Floor> getFloorMap(int floorCount, Map<String, MainCorridor> mainCorridorMap, Map<String, SubCorridor> subCorridorMap) 

 Map<String, Floor> floorMap = new HashMap<>();

 for (int i = 0; i < floorCount; i++) 

 String id = "Floor-" + i;

 Floor floor = new Floor(id, mainCorridorMap, subCorridorMap);

 floorMap.put(id, floor);
 

 return floorMap;
 

 private Map<String, SubCorridor> getSubCorridorMap(int subCorridorsCount) 

 int lightId = 0;

 int acId = 0;

 Map<String, SubCorridor> subCorridorMap = new HashMap<>();

 for (int i = 0; i < subCorridorsCount; i++) 

 Light light = new Light("Light-" + lightId++);
 light.switchOFF();

 AirConditioner airConditioner = new AirConditioner("AC-" + acId++);
 airConditioner.switchON();

 String subCorridorId = "SubCorridor-" + i;

 SubCorridor subCorridor = new SubCorridor(subCorridorId, Arrays.asList(light), Arrays.asList(airConditioner));

 subCorridorMap.put(subCorridorId, subCorridor);
 

 return subCorridorMap;
 

 private Map<String, MainCorridor> getMainCorridorMap(int mainCorridorCount) 

 int lightId = 0;

 int acId = 0;

 Map<String, MainCorridor> mainCorridorMap = new HashMap<>();

 for (int i = 0; i < mainCorridorCount; i++) 

 Light light = new Light("Light-" + lightId++);
 light.switchON();

 AirConditioner airConditioner = new AirConditioner("AC-" + acId++);
 airConditioner.switchON();

 String mainCorridorId = "MainCorridor-" + i;

 MainCorridor mainCorridor = new MainCorridor(mainCorridorId, Arrays.asList(light), Arrays.asList(airConditioner));

 mainCorridorMap.put(mainCorridorId, mainCorridor);
 

 return mainCorridorMap;
 

 @Override
 public void printStatus() 
 hotel.printStatus();
 

 @Override
 public void actOnMotionEvent(Address address) 

 hotel.motionDetected(address);

 MotionWatcher watcher = motionWatcherMap.get(address);

 if (watcher == null) 

 watcher = new MotionWatcher(this, address);

 motionWatcherMap.put(address, watcher);

 new Thread(watcher).start();

 return;
 

 watcher.renewWaitingPeriod();
 

 @Override
 public void destroyMotionWatcher(Address address) 

 hotel.cleanFloor(address);

 motionWatcherMap.remove(address);

 System.out.println("After no motion is detected for some specified time ....... ");

 hotel.printStatus();
 

public class MotionWatcher implements Runnable 

 private IController controller;

 private Address address;

 private static int waitTimeinSeconds = 10;

 private volatile boolean gotoSleep = true;

 MotionWatcher(IController controller, Address address) 
 this.controller = controller;
 this.address = address;
 

 @Override
 public void run() 

 long startTime = System.currentTimeMillis();

 while (gotoSleep) 
 try 
 Thread.sleep(waitTimeinSeconds * 1000);
 gotoSleep = false;
 catch (InterruptedException e) 
 e.printStackTrace();
 
 

 System.out.println("Waited for " + (System.currentTimeMillis() - startTime) + " millieseconds.......");
 controller.destroyMotionWatcher(address);
 

 void renewWaitingPeriod() 
 gotoSleep = true;
 

For Testing if the code works as expected (in single thread env..)

public class Tester 

 public static void main(String[] args) throws InterruptedException 

 IController controller = new Controller(1, 1, 2);

 Listener listener = new MotionListener(controller);

 System.out.println("INITIAL STAGE...........");
 controller.printStatus();

 listener.eventOccurred("Floor-0", "SubCorridor-0");

 System.out.println("AFTER MOTION DETECTED............");
 controller.printStatus();

 Thread.sleep(4 * 1000);

 listener.eventOccurred("Floor-0", "SubCorridor-0");

 System.out.println("AFTER SECOND MOTION DETECTED................");
 controller.printStatus();
 

Well I do realize there is more than one way to solve a problem using OOP techniques, I just want to know if my OOP solution can be improved (assuming I used and follwed OOP principles). All suggestions or criticism are welcome because the I believe thats the only way to get good on this game.

Not a full review, but some initial thoughts:

Structure

• You define SPECPOWER, but still hardcode the value inside methods. This will surely lead to bugs if you decide to change only the field.


• Is there equipment that can be on or off, but which doesn't consume power? If not, I would pull power into equipment (and rename it). If yes, I would add a generic electronic device class. Either will get rid of the duplicate getPowerConsumption implementation.


• I don't like that getTotalPowerConsumption and similar methods need to know about the specific devices (lights, airconditioners). If you need to add say a security camera later on, you will need to add it in many places, and forgetting some will lead to bugs. Possible solutions would be to put all devices in a devices list (which might cause performance issues if you only want to get one specific type), or a different structure such as a map. Your constructors would also need to change then.


• Why does a floor have switchedOFFACs when the corridors already have the ACs? This doesn't seem necessary and is confusing. Also, is there a reason that it is a queue?

Documentation

You don't have any. I would think about adding javaDoc comments to at least some methods. Eg what does getMaxPower do? And how is it different from getTotalPower? You probably know now, but will you remember in a couple of months?

Naming

• Try to be consistent with your names, eg:AC vs Airconditioner
  


• I wouldn't use reverse hungarian notation (but if you do, it should be consistent); mainCorridorMap should simply be mainCorridors. This is especially confusing as there are things called floor maps, but your floorMap field doesn't contain one.


• 
  Address seems like a confusing name. I don't think that you need it at all, but if you do, maybe CorridorLocation?


• 
  clearMotionEvent: Here, we aren't really dealing with any events. I would probably rename it to turnLightsOff, and motionDetected to turnLightsOn.

Misc

• Always use curly brackets, even for one-line statements. Not using them can cause bugs. (but if you disagree, you should be consistent)

Thanks for sharing your code.

OOP

OOP doesn't mean to "split up" code into random classes.

The ultimate goal of OOP is to reduce code duplication, improve readability and support reuse as well as extending the code.

Doing OOP means that you follow certain principles which are (among others):

• information hiding / encapsulation


• single responsibility


• separation of concerns


• KISS (Keep it simple (and) stupid.)


• DRY (Don't repeat yourself.)


• "Tell! Don't ask."


• Law of demeter ("Don't talk to strangers!")

One basic rule of thumb is: create a new class if there is a difference in behavior. your classes Light and AirConditioner only differ in configuration (the number they return for power consumption when on).

Naming

Finding good names is the hardest part in programming, so always take your time to think about the names of your identifiers.

Naming Conventions

Please read (and follow) the
Java Naming Conventions

E.g.: your methods and variables have names like switchOFF and isON which should better be switchOff and isOn.

misleading naming

Some of your methods have somewhat misleading names.

E.g.: getMaxPower() implies the access to an objects property while it in deed calculates the max power. Therefore it should better be named calculatePowerConsuption().

how to execute this program on eclipse?