Java Interview Questions

What is UML?

Graphical language for visualizing, specifying, constructing and documenting the artifacts of the system. allows to create blueprints of all the aspects of the system, before physically implementing the system.

What is modeling? What are the advantages of creating a model?

Well-accepted engineering technique which helps build a model. Model is the simplification of reality; blueprint of the system that needs to be built. Model helps you visualize the system. helps to specify the structural and behaviour of the sytem. helps make templates for constructing the system. helps document the sytem.

What are the different views considered when building an object-oriented software system? there aer 5 veiws:

1. Use case view: exposes requirements of a system.
2. Design view: capturing the vocabulary
3. process view: modeling the distribution of the sytems processes and threads.
4. implementation veiw: addressing the physical implementation of the system.
5. deployement view: focus on the modeling of components required for deploying the system.

What are the major three types of modeling used?

They are 9: Use case diagram, class diagram, object diagram, sequence diagram, statechart diagram, collaboration diagram, activity diagram, component diagram, deployment diagram.

SDLC: Software development life cycle. SDLC of a system includes processes that are Use case driven, architecture centric and iterative and incremental. Life cycle is divided into phases. Phase is a time span between two milestones. The milestones are Inception, Elaboration, construction, and transition. Process workflows that evolve through these phase are Business Modelling, Requirement gathering, Analysis and Design, Implementation, Testing, Deployment. Supporting workflows are configuration and change management, Project management.

What are relationships?

1. Dependencies: relationship between two entities such that a change in specification of one thing may affect the other. used to show that one class uses another class as an argument in the signature of the operation.
2. Generalization: relationships specified in the class subclass scenario, it is shown when one entity inherits from other.
3. Associations: structural relationships. ‘A room has walls’, ‘Person works for a company’.
4. Aggregation: type of association where there is-a, has-a relationship.

* Static Diagrams (Structural diagrams): Class diagram, Object diagram, component diagram, deployment diagram.
* Dynamic diagram(Behavioral diagrams): Use case diagram, sequence diagram, collaboration diagram, activity diagram, statechart diagram.

Messages: Specification of a communication, when a message is passed that results in action that is in turn an executable statement.

Use Case: specifies the behavior of a system or a part of a system. Involves the interaction of actors and system.

Aggregation: One class owns but shares a reference to objects of another class. Child refrerence exists even if parent oject rereference is set to null. Symbol: empty diamond arrow.

Composition: one class contains objects of another class. child reference does not exists independently. Symbol: filled diamond arrow.

Stereotype: Extension to existing UML vocabulary. It is used to create new model elements or derive from existing ones having specific properties pertaining to problem domain. EG: you can create steriotype, <> derived from existing one, <>.

Tags: UML interview questions

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