OOAD And UML Interview Questions

In this article we will learn Object Oriented Analysis Design Interview Questions which are frequently asked in interview for freshers and experienced developers. This course specially for Beginners since providing Basic OOAD and UML interview questions for all programming language developers. You might be strong knowledge on java but interviewer always used test your weakness area. So don't give chance to him,before attending interview brush up these top OOAD and UML interview questions to clear technical round confidently.


1) What is UML?

Ans: UML means Unified Modeling Language. It is a standard language for designing and documenting a system in Object Oriented manner. It gives a standard way to  write a software system's blueprint including conceptual things like business process and system functions. It has nine diagrams which can be used in design document to express design of software architecture.

2) Can you explain class Diagrams?

Ans:  class diagram is basically a prototype which helps us create objects. Class diagram model the static structure of the project. A class represents family of an object. By using class we can create objects. It shows relationships between classes,objects,attributes and operations.

Basically there are important sections which are shown above. Let's try to understand each section.

Class name:  This is the first section or top most section of the class which represents the name of the class. Example(Employee,Customer,Student,Vehicle etc....)

Attributes:  This is the middle section of the class which represents the properties of the system. Example(Emp_id,Emp_name,salary etc...)

Methods:  This section carries operation or method to act on attributes.

To Know more about:  class and Object in java with examples

3) How do we represent private,public and protected in class Diagrams?

Ans: In order to present visibility for attributes and methods in class diagram we have to place symbols before each attribute and methods. Let us try to understand with diagram to clarify.

4 What is Aggregations and composition in class diagrams?

Ans:  The aggregation has a 'Strong-type'. This association signifies that the whole object can exist without the aggregated object. That means Association with "whole-part" relationship.

Example:  You can take a car, which contains the wheels and some extra parts. Even though the parts are not there we can call it as car. But in the case of composition, it is a special type of aggregation it represent weak relationship between "whole-part". In this case the whole-part  is affected when the part within that got affected. 

From the above figure, there are three classes Department class,University class and Professor class. The University can not exist without Department that means it is strong relationship between them. In other words the lifetime of  University depend on the lifetime of the department class. The second association represents "weak-type"  between Department and professor class. Since department is not depend on the professor  this is called as composition association.

5)  What are static and dynamic modeling?

Ans:  Static modeling is used to specify structure of the object that exist in the problem domain. These are express using class,object and Use-case diagrams. In case of dynamic binding the objects interactions during run time. It is represented by sequence,activity,collaboration and state chart diagram.

6) What is the use of Use Case Diagrams?

Ans:  Use case diagram answers what system does from the user point of view. Use case answer what will the system do? It is mainly used in requirement document to specify clarity regarding a system. There are mainly three parts in Use case diagrams. They are

They are  a) Scenario b) Actor c) Use Case

a) Scenario:  It is a sequence of event which happen when a user interacts with the system.

b) Actor:  Actor is the who of the system that means end user.

c) Use Case: Use Case is a task or the goal performed by the end user.

7) What are the Building Block of UML?

Ans: 

Things:

• Structural Things
• Behavioral Things
• Grouping Things
• Annotational Things

Relationships:

• Dependency
• Association
• Generalization
• Realization

Diagram:

• Class diagram
• Object diagram
• Use case diagram
• Sequence diagram
• Collaboration diagram
• Activity diagram
• Component diagram
• Deployment diagram

Grouping things:

package

Annotation Things:

Notes

8)What is Architecture?

Ans:  It takes care structural and behavioral aspect of a software system. It includes software usage,functionality,performance,reuse,economic and technology constraints.

9) what is do you understand about analysis and design?

Ans:  Analysis means the process of determining what needs to be done before  how it should be done.  To accomplish all these thing you should refers the existing systems and documents. In other words  it is an art of discovery of your requirements to achieve.

Designing means the process of choosing the one among many,which best accomplishes user needs. 

10) What are the main concepts in Object Orientation?

Ans:  The main concepts in Object orientation are 

• Objects
• Inheritance
• Polymorphism
• Abstraction