Access subclass variables in an ArrayList?

Question

I have a Shop class that has an array list of type Worker, and I have two classes that inherit (extend) from Worker, called Stocker and Cashier.

My Stocker class adds the variable

int stamina;

and my Cashier class adds the variable

int patience;

Within Shop, I have an ArrayList named workers of type Worker, my questions are:

1) Is it wrong to be adding objects of types Stocker and Cashier into workers even though they both extend from the Worker class?

2) How can I access the variables of the subclasses from the ArrayList? I've tried to use:

workers.get(0).getStamina();

(knowing for a fact that I have added a class of type Stocker to my ArrayList at index 0) - however this does not work..

How can I freely access and use these subclasses from an ArrayList of type superclass?

Paul Boddington · Accepted Answer · 2015-10-20 23:32:36Z

2

You have to cast a Worker to a Stocker to do that:

((Stocker) workers.get(0)).getStamina();

However you may want to consider changing your design so that you do not have a list of items of different types.

answered Oct 20, 2015 at 23:32

Paul Boddington

37.8k10 gold badges69 silver badges120 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Hazim Over a year ago

So make 3 different ArrayLists? One for Worker, Stocker, and Cashier? Is it wrong to make an ArrayList using subclasses of a superclass?

Paul Boddington Over a year ago

If you have an ArrayList, you should normally use the elements in the same way. Since you want to call different methods, 3 lists may be better

John3136 · Accepted Answer · 2015-10-20 23:34:25Z

1

The ArrayList can store Workers and Stockers in the same collection, but if you say ArrayList<Worker> then the collection only knows about Workers and not Stockers.

You need something like:

Worker worker = workers.get(0);
if (worker instanceof Stocker)
{
    Stocker stocker = (Stocker)worker;
    //stocker.getStamina();

answered Oct 20, 2015 at 23:34

John3136

29.3k4 gold badges55 silver badges77 bronze badges

Collectives™ on Stack Overflow

Access subclass variables in an ArrayList?

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related