How do I check the type of a subclass?

Question

I want to check the type of a subclass in Java. Here's the pseudocode I want to achieve:

public class Brown { ... }
class Poo extends Brown { ... }
class Brownie extends Brown { ... }
...

ArrayList<Brown> brownThings = new ArrayList<Brown>();
...

for (Brown i: brownThings)
    // if i is a brownie eat
    // else dispose of

Suresh Atta · Accepted Answer · 2014-02-10T08:41:54.227

4

You can use instanceof key word

if (i instanceof Brownie ) {
    // do something
  }

That exactly checks the instance type.

edited Feb 10 '14 at 08:41

answered Feb 10 '14 at 08:31

Suresh Atta

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I think that it wanna check if it is a Brownie not a Poo. – PhoneixS Feb 10 '14 at 08:38
You need not to check, everything is `Brownie` in that list then :), Since every `Child` is `Parent` – Suresh Atta Feb 10 '14 at 08:40
Everything in the list is Brown not Brownie (a subclass of Brown) – PhoneixS Feb 10 '14 at 08:41
Oops ..Ooops, sorry. Edited. – Suresh Atta Feb 10 '14 at 08:41

score 1 · Answer 2 · edited May 23 '17 at 10:25

1

You can use instaceof operator. For example:

if (i instanceof Brownie) {
  eat(i);
} else {
  dispose(i);
}

instaceof opertaor check if the type of an object is an instance of a class or a class that extends or implements the specified type.

You can read more in Java tutorial, operators. Also see question What is the instaceof operator used for.

edited May 23 '17 at 10:25

Community

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answered Feb 10 '14 at 08:32

PhoneixS

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score 0 · Answer 3 · answered Feb 10 '14 at 08:31

0

instanceof can handle that just fine.

answered Feb 10 '14 at 08:31

Sureshkumar Panneerselvan

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score 0 · Answer 4 · answered Feb 10 '14 at 08:32

0

This should do:

for (Brown i: brownThings) {
    if (i instanceof Brownie) {
        //eat
    }
}

answered Feb 10 '14 at 08:32

Pieter

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How do I check the type of a subclass?

4 Answers4