---
title: "Short note: Flow of object"
subject: "Object Oriented Analysis and Design"
chapter: 2
key: "semester_6/object_oriented_analysis_and_design:short-note-flow-of-object"
source: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-flow-of-object
site: BCT Engineering
---

# Short note: Flow of object

Object Oriented Analysis and Design · Chapter 2: Object Oriented Analysis

- Asked in: 2069 Poush, 3 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-flow-of-object
- Whole chapter: https://www.bctengineer.com/md/semester_6/object_oriented_analysis_and_design/chapter-2

## Question

Write a short note on Flow of object [?].

## Short answer

Object flow in activity diagrams passes data objects between actions, showing state changes. An object rectangle and dashed arrow denote flow. It reveals data dependencies and helps identify classes and their states as objects move through the workflow.

## Answer

(Interpreted as **object flow** in an activity diagram.)

An **object flow** shows that an *object* (data or product) is produced or consumed by an action, and passes from one activity to the next. In an activity diagram a **control flow** only says "what happens next", while an **object flow** also says "what is passed".

#### Notation
- The object is drawn as a **rectangle** with the name (and state in brackets): `Order [placed]`.
- An object flow is a **dashed or solid arrow** from the action producing the object to the object node, and another arrow from the object to the action consuming it.
- Input and output pins on actions can show the same idea.

```text
 [ Take Order ]
        |
        v
   +----------+
   |  Order   |
   | [placed] |
   +----------+
        |
        v
 [ Validate Order ]
        |
        v
   +-----------+
   |  Order    |
   | [verified]|
   +-----------+
        |
        v
  [ Ship Order ]
```

#### Uses
- Shows how an object changes **state** as it moves through the workflow.
- Shows data dependencies between activities.
- Helps identify classes and their state diagrams, since the object states appear in the flow.

The same object may appear several times in different states to show its life cycle within the process.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does an object flow show that a control flow does not?
   A. What data/object is passed between actions
   B. The start node
   C. The order of actions
   D. The swimlane
   Answer: A. Control flow shows what happens next; object flow also shows what is passed. (Key point: Object flow vs control flow)

2. How is an object node drawn in an activity diagram?
   A. A diamond
   B. A filled circle
   C. A thick bar
   D. A rectangle with the object name and optional state
   Answer: D. Objects are rectangles such as Order [placed]. (Key point: Notation)

3. Showing Order [placed] then Order [verified] illustrates:
   A. A decision
   B. The object changing state through the workflow
   C. A fork and join
   D. Two different classes
   Answer: B. The same object appears in different states along the flow. (Key point: State change)