Object descriptions

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which item is listed in an object description?

A The object name, its attributes with data types, and its methods

B Only the final output shown on screen

2. Which attribute entry is written correctly in an object description?

A studentName - print()

B studentName - String

3. What does the methods section of an object description show?

A The data type of every attribute

B What each method does and the parameters it needs

4. Which is a sensible object name for an object description?

A Student

B calculateTotalMark()

5. Which method row is complete in an object description?

A setMark(newMark) - changes the student's mark to a new value

B setMark - Integer

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Object name: Student		AThe attributes have no data types listed. Each attribute needs a type, such as studentName (String) and yearLevel (Integer).
2Methods: calculateAverage(marks) - returns the mean mark		BAttributes: studentName (String), yearLevel (Integer)
3Each attribute in an object description is listed with its name and its data type.		CThe methods section is missing. The description should list methods such as getTitle() with their parameters and purpose.
4An object description differs from a data dictionary because it also lists the methods the object can perform.		DNames the class or object being described, such as Student, at the top of the object description.
5Object name: Student Attributes: studentName, yearLevel		ELists a behaviour of the object with its parameters and a short statement of what it does.
6Object name: Book Attributes: title (String), pages (Integer) Methods: (none listed)		FMethods: setYearLevel(newLevel) - changes the year level

Definitions

object description

Fill in the Blanks

Complete each line of code by filling in the missing parts.

___________: Student Attribute: studentName (String)

Object name: Product Attribute: price (_____)

Object name: Book Attribute: isBorrowed (_______)

Object name: Student Method: addPoints(______) Purpose: adds to the points attribute

Object name: Account Attribute: balance (Float) ______: deposit(amount)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Object: Book

B Attribute: title (String)

C Attribute: pages (Boolean)

D Method: getTitle() -> String

Question 2

A Object: Student

B Attribute: name (String)

C Attribute: mark (Float)

D Method: getMark() -> Boolean

Question 3

A Object: speed (Integer)

B Attribute: speed (Integer)

C Method: accelerate(amount)

Question 4

A Object: Pet

B Attribute: age

C Attribute: name (String)

D Method: feed() - adds food

Question 5

A Object: Account

B Attribute: deposit(amount)

C Method: withdraw(amount)

D Method: getBalance() -> Float

Answer Key

Object descriptions

Section A: Quick Questions

A — The object name, its attributes with data types, and its methods

B — studentName - String

B — What each method does and the parameters it needs

A — Student

A — setMark(newMark) - changes the student's mark to a new value

Section B: Match the Pairs

Object name: Student → Names the class or object being described, such as Student, at the top of the object description.

Methods: calculateAverage(marks) - returns the mean mark → Lists a behaviour of the object with its parameters and a short statement of what it does.

Each attribute in an object description is listed with its name and its data type. → Attributes: studentName (String), yearLevel (Integer)

An object description differs from a data dictionary because it also lists the methods the object can perform. → Methods: setYearLevel(newLevel) - changes the year level

Object name: Student Attributes: studentName, yearLevel → The attributes have no data types listed. Each attribute needs a type, such as studentName (String) and yearLevel (Integer).

Object name: Book Attributes: title (String), pages (Integer) Methods: (none listed) → The methods section is missing. The description should list methods such as getTitle() with their parameters and purpose.

Section C: Definitions

object description — A design table for a class that lists its name, its attributes with data types, and its methods with their parameters and purpose.

Section D: Fill in the Blanks

Object name: Student
Attribute: studentName (String)

Object name: Product
Attribute: price (Float)

Object name: Book
Attribute: isBorrowed (Boolean)

Object name: Student
Method: addPoints(points)
Purpose: adds to the points attribute

Object name: Account
Attribute: balance (Float)
Method: deposit(amount)

Section E: Spot the Error

C — A page count is a whole number, so the attribute's data type should be Integer, not Boolean.

D — getMark() returns the mark attribute, which is a Float, so the method must return Float, not Boolean.

A — The first line of an object description gives the object's name (Car). Attributes and their data types come on later lines.

B — Every attribute in an object description needs a data type. It should be Attribute: age (Integer).

B — deposit(amount) is an action that takes a parameter, so it is a method. Attributes store data and have a data type, so this line should start with Method:.