Question

Explain what composition is and how to use it.

Answer 1

Answer)
The composition is one of the many features of the object-oriented programming languages such as Java. The composition allows is to describe a class which references on or more than one objects which are in the other classes, for the instance variables. Composition allows us to have a has-a relationship between objects. Thus using this we can reuse the existing code, and also change the implementation of a class.
The composition is done using simple objects creation and then re-using the code in the other class in the current class. Thus using this the other class code is not affected and also also the code can be re-used in the current class. This should be used in the approach when the classes relationship depicts the has-a relationship and thus we should use composition rather than inheriting the entire class. Thus using this the client class code or anything does not need to be changed, and we can have the current class bear the change and also reuse the code.