What is Code Aggregation
If there is an entity reference in a class, then you what you have is a code aggregation. Aggregation usually represents HAS-A relationship.
Consider the following situation situation.
A Worker object contains many informations such as id, name, phone number etc. It contains one more object named address, which contains its own informations such as city, state, country etc. see it as given below.
The programming language that I specialize in is Java, because I think Java programming language is more universal and of course because I like it regardless of any reason.