OOPS Concept

Abstraction? Ans) Abstraction is way of converting real world objects in terms of class. For example creating a class Vehicle and injecting properties into it. E.g public class Vehicle { public String colour; public String model; }

Encapsulation? Ans) The encapsulation is achieved by combining the methods and attribute into a class. The class acts like a container encapsulating the properties. The users are exposed mainly public methods.The idea behind is to hide how thinigs work and just exposing the requests a user can do. eg private variables getter() setter()

Association? Ans) Association is a relationship between two classes. In this relationship the object of one instance perform an action on behalf of the other class. The typical behaviour can be invoking the method of other class and using the member of the other class. public class MyMainClass{ public void init(){ new OtherClass.init(); } }

Aggregation? Ans) Aggregation has a relationship between two classes. In this relationship the object of one class is a member of the other class. Aggregation always insists for a direction. public class MyMainClass{ OtherClass otherClassObj = new OtherClass(); }

Q8) What is Composition? Ans) Composition is a special type of aggregation relationship with a difference that its the compulsion for the OtherClass object (in previous example) to exist for the existence of MyMainClass.