UML Object Diagram

Object diagrams are dependent on the class diagram as they are derived from the class diagram. It represents an instance of a class diagram. The objects help in portraying a static view of an object-oriented system at a specific instant.

Both the object and class diagram are similar to some extent; the only difference is that the class diagram provides an abstract view of a system. It helps in visualizing a particular functionality of a system.

Notation of an Object Diagram

Purpose of Object Diagram

The object diagram holds the same purpose as that of a class diagram. The class diagram provides an abstract view which comprises of classes and their relationships, whereas the object diagram represents an instance at a particular point of time.

The object diagram is actually similar to the concrete (actual) system behavior. The main purpose is to depict a static view of a system.

Following are the purposes enlisted below:

• It is used to perform forward and reverse engineering.
• It is used to understand object behavior and their relationships practically.
• It is used to get a static view of a system.
• It is used to represent an instance of a system.

Example of Object Diagram

How to draw an Object Diagram?

1. All the objects present in the system should be examined before start drawing the object diagram.
2. Before creating the object diagram, the relation between the objects must be acknowledged.
3. The association relationship among the entities must be cleared already.
4. To represent the functionality of an object, a proper meaningful name should be assigned.
5. The objects are to be examined to understand its functionality.

Applications of Object diagrams

The following are the application areas where the object diagrams can be used.

1. To build a prototype of a system.
2. To model complex data structures.
3. To perceive the system from a practical perspective.
4. Reverse engineering.

Class vs. Object diagram