Check attribute of a subclass

Question

I stumbled across that situation but I don\'t know how to handle it the right way:

class Myclass { }
class MyclassWithAwesomeStuff extends Myclass {
    public b         


        

Answer 1

Just use an interface:

interface AwesomeStuffable{

    public boolean isAwesome();

}

let your classes implement it:

class MyClass implements AwesomeStuffable{

  public boolean isAwesome(){

    //your logic here

  }

}

And let your ArrayList hold just AwesomeStuffable objects.

Answer 2

Just to get yourself unblocked, you can do the following:

if (m instanceof MyClassWithAwesomeStuff) {
    if (((MyClassWithAwesomeStuff) m).awesomeStuff) {

    }
}

But, using instanceof defeats the purpose of inheritance and it appears to be a design flaw to have a need to check for this flag for only some objects in list in your code. If you expand the context, probably something better can be suggested.

Answer 3

Test if m is a MyclassWithAwesomeStuff with the instanceof operator.

if (m instanceof MyclassWithAwesomeStuff)
{
    MyclassWithAwesomeStuff mwas = (MyclassWithAwesomeStuff) m;
    // Now you can access "awesomeStuff" with "mwas"
}