Question

Consider the DataSource class in below code. Explain how inheritance is intended to be used with this class. Does this represent a good use of inheritance? Explain your answer

// Base class for game configuration

public abstract class DataSource {

    private Graph map;

    private HashMap <String,Room> rooms;

    private ArrayList <Entity> entities;

    private Player player;

    protected HashMap < String, List<String[]> > tables;

    // constructor

    public DataSource() {

    }

    // Connect to the data source. Override if source is a database

    public void connect() {

    };

    // Load the configuration tables required to build the game world

    public abstract void load();

    // Build the game world

    public final void build() {

      // code omitted

    }

// Disconnect from the data source. Override if source is a database

    public void disconnect() {

    };

    // Get a the layout of the game world

    public Graph getMap() {

       return map;

    }

    // Get room details. The HashMap key is the room label.

    public Map <String,Room> getRooms() {

        return rooms;

    }

    // Get player details

    public Player getPlayer() {

        return player;

    }

    // Get entity (bats, bird, monsters, wumpus) locations

    public List <Entity> getEntities() {

        return entities;

    }  

}

Answer 1

Inheritance

Yes, this class represents good use of inheritance.

Some unnecessary things you need to remove are:

1. unnecessary semi-colon at end of connect method
2. same with disconnect method

Some things you need to add:

1. Since there is no built-in(primitive) datatype named 'Player' in java, so you definitely have to create Player class.
2. Same, you'd have to create Room class

Also, it has load method which is abstract which would be implemented by child classes.

An example of how to use it (in child class) is as follows:-

public DataBase extends DataSource {

   /*
       We can access protected field which is tables in our case
       We cannot access other fileds, just can access public methods
   */

   public static void main(String[] args) {

   }
  
   @Override
   public void load() {
  
   }

   // And if we want to implement connect/disconnect methods, do it as following:-

  
    @Override
    public void connect() {
    super.connect();   # A call to super(parent) class which is DataSource class's connect method
    }

@Override
   public void disconnect() {
    super.disconnect();
   }
}

-------------------------------------------------------------------
COMMENT DOWN FOR ANY QUERIES!!!
HIT A THUMBS UP IF YOU DO LIKE IT!!!