Questionnaires

1> What is the difference between aggregation and composition?
Answer:
Composition and Aggregation are two variants of association.
Aggregation implies a "has-a" relation where child class can exist independently 
of the parent class.It is a weak variant of association.
Composition is a strong form of association which implies a "is part-of"
relation where the child cannot exist independent of the parent.

2> Does a constructor has to be created with the creation of an object?
Answer:
No, a constructor need not be created at the time of object creation. In JAVA, 
object is created through the use of new operator, and not by the constructor invocation.
Generally, object is already created before any constructor is invoked.
Constructor acts as a resource allocator and state initializer for an object.
It does not create object itself, but initializes the state of the objects.

3> What is default and parameterized constructor?
Answer:
Default Constructor – A constructor that accepts no parameters. It is implicitly defined and called if not done explicitly.
Parameterized Constructor – A constructor which accepts a specific number of parameters to initialize data members of a class with distinct values.
A parameterized constructor should be explicitly defined inside the class.

4> Explain the three specific characteristics of an object.
Answer :
The three specific characteristics of an object are :
i) State : object has various properties, which might change.
ii) Behaviour : object can do things and can have things done on it.
iii) Identity :  each object is a distinct entity.
