Avoid excessive use of the instanceof operator

Many hold that the instanceof operator should be used only as a last resort, and that an overridden method is usually (but not always) a better alternative.

This is because, if one object is of type T1, it wouldn't guarantee that object T2, which returns True in case of (T2 instanceof T1), may be of type T1. This is because T2 may belong to subclass of T1, as instanceof returns true than as well. See how we used it in equals method.