Object diagram

According to the UML 2.5 diagram overview:

Instance level class diagram which shows instance specifications of classes and interfaces (objects), slots with value specifications, and links (instances of association).

Object diagram was defined in now obsolete UML 1.4.2 Specification as "a graph of instances, including objects and data values. A static object diagram is an instance of a class diagram; it shows a snapshot of the detailed state of a system at a point in time." It also stated that object diagram is "a class diagram with objects and no classes."

UML 2.5 specification simply provides no definition of object diagram.

Features

• Most of the features comes from the class diagram
• The name of the connection shows the label the field can be accessed
• Directional arrows means one way attributes
  • So from the attribute, you can't access the parent
• Simple lines are bidirectional connections
  • they have each other as attributes or fields
• Default values can be shown as named instances
• Unique, yet anonymous instances are grouped with an underlined colon (:)

Example