instanceof keyword usage

Question

Is using the instanceof keyword against the essence of object oriented programming? I mean is it a bad programming practice? I read somewhere that us

Answer 1

Usage of instanceof is discouraged when same effect can be achieved via virtual methods, like in example of thomson_matt. However, it's necessary to use instanceof in some circumstances. For example, when your code gets Object from external source, say, network or third-party API which returns Object, and you must decide what is the type of this Object and act appropriately.