Test Prep 11 - Dynamic Binding, Interfaces and Abstract Classes

A. Dynamic Binding:

1. When a super class type of object is declared, the reference(for instance, x) can point to either a _________ class object or a _________class object.

2. If a method (say, do()) in super class is overridden in the subclass, in the above case, will x.do() call the super class version or sub class version?

3. Down casting: if a super class reference points to a subclass object, and a "subclass only" method is called, a downcasting is needed to make the call otherwise compile time error will occur.

B. Interfaces:

1. The story of last digit.

2. How many interfaces can a class implement? why?

3. Can interface type be used to declare objects?

C. Abstract Classes:

1. What if a class implements only part of the interface?

2. Can abstract classes become super classes?

3. What if the abstract methods are not implemented in sub classes either?

D. Comparable Interface:

public interface Comparable{
int compareTo(Object obj);
}

E. Challenge of the Week: All MC questions of Chapter 4.