Access extended class method

Question

I have a class called Occupant and extended Occupant classes for different occupant types such as Animal, Food, Tools, Treasure.

All occupants are placed on GridSquares, A Square can hold up to 3 occupants.

Occupant class has a method to get all the Occupants on a GridSqure when the position is given. The method will return a Occupant Array with extended occupant classes.( E.G: An Animal, A Tool and A Food).

   Occupant[] allOccupants = newGridSquare.getOccupants();

    for ( Occupant oneOccupant : allOccupants)
      {
         if(oneOccupant.getStringRepresentation() == "A")
         {

             player.reduceStamina(oneOccupant.getDanger());

         }
     }

compiler cannot access getDanger method in Animal class just because I already have assigned it as Occupant.

How can I access getDanger method in extended Occupant class Animal?

Related: [How do I compare strings in Java?](http://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java) — Sotirios Delimanolis, Sep 22 '13 at 07:15
Your question is unclear; are you saying that only `Animal` has a `getDanger` method, and `Occupant` doesn't? Please post the code for the classes. — chrylis -cautiouslyoptimistic-, Sep 22 '13 at 07:15
Also, are you trying to use `stringRepresentation` to indicate the class of the `Occupant`? There are much cleaner and safer ways to do that in Java; `instanceof` is generally best, and an `enum` is far better than the string. — chrylis -cautiouslyoptimistic-, Sep 22 '13 at 07:18

score 1 · Accepted Answer · edited May 23 '17 at 11:50

You can cast the instance

for ( Occupant oneOccupant : allOccupants)
{
    if("A".equals(oneOccupant.getStringRepresentation()))
    {
        Animal animal = (Animal) oneOccupant;
        player.reduceStamina(animal.getDanger());
    }
}

Assuming the "A" is an identifier for an Animal instance and Animal is a subclass of Occupant and has a getDanger() method. Otherwise, first do a check

if (oneOccupant instanceof Animal) {
     Animal animal = (Animal) oneOccupant;
     player.reduceStamina(animal.getDanger());
}

How do I compare strings in Java?

score 0 · Answer 2 · answered Sep 22 '13 at 07:21

As getDanger does not exists under Occupant class but in specific class Animal. So you you need to downcast oneOccupant To Animal class .

Another solution is you declare getDanger under Occupant class and implement it under extended class. In case of classes except Animal, you can provide empty implementation. But thats not a good approach from design point of view but sometime is resorted to in case of legacy code

Access extended class method

2 Answers2