Aggregations and Identity

Aggregation

• Aggregation represents a relation “contains”,“is a part of”, “whole-part” relation.

• Indicated by a line adorned on the “whole” bya hollow diamond– Along with name of relationship and– Cardinality.

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• Aggregation represents a relation “contains”,“is a part of”, “whole-part” relation.

• Indicated by a line adorned on the “whole” bya hollow diamond– Along with name of relationship and– Cardinality.

Aggregation: Example

containsLeague Team

*

Membership aggregation: A league is made up ofMany teams.

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Membership aggregation: A league is made up ofMany teams.

made ofAuto

wheel

engine

4

1

part*

Strong aggregation.

Generalization

• Generalization is a relationship between a generaland a specific class.

• The specific class called the subclass inherits fromthe general class, called the superclass.

• Public and protected properties (attributes) andbehaviors (operations) are inherited.

• Design representation “inheritance” OO concept.

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• Generalization is a relationship between a generaland a specific class.

• The specific class called the subclass inherits fromthe general class, called the superclass.

• Public and protected properties (attributes) andbehaviors (operations) are inherited.

• Design representation “inheritance” OO concept.

Generalization: Symbol

• It represents “is a” relationship among classesand objects.

• Represented by a line with an hollow arrowhead pointing to the superclass at thesuperclass end.

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• It represents “is a” relationship among classesand objects.

• Represented by a line with an hollow arrowhead pointing to the superclass at thesuperclass end.

Generalization: Example

Vehicle

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Car Boat Truck

Combined Example

VehiclePersondrives

0..*

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Car Boat Truck

Discovering ClassesLibrary Management System (LMS)

RESPONSIBILITIES

1. Borrow item2. Reserve item3. Return item4. Remove reservation5. Add borrower6. Update or remove borrower7. Add title (book or magazine)8. Update or remove title9. Add item10. Update or remove item11. Store loan details

COLLABORATIONS

Item

ReservationBorrower

TitleBook TitleMagazine Title

Loan (Transaction)

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RESPONSIBILITIES

1. Borrow item2. Reserve item3. Return item4. Remove reservation5. Add borrower6. Update or remove borrower7. Add title (book or magazine)8. Update or remove title9. Add item10. Update or remove item11. Store loan details

COLLABORATIONS

Item

ReservationBorrower

TitleBook TitleMagazine Title

Loan (Transaction)

Database

CRC Cards

• LMS• (Librarian)• Borrower• Title: Book Title, Magazine Title• Item• Reservation• Transaction (Loan)• Database for storage

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• LMS• (Librarian)• Borrower• Title: Book Title, Magazine Title• Item• Reservation• Transaction (Loan)• Database for storage

Static Analysis: Initial ClassDiagram

Objects of theseclasses are allpersistent data (ina Database)

BookTitle MagazineTitle0..1LoanTransaction

0..*

Borrower

0..* 0..*

Item

0..1

0..*

Reservation

0..*

0..*

Title

0..*

0..*

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Objects of theseclasses are allpersistent data (ina Database)

BookTitle MagazineTitle0..1LoanTransaction

0..*

Borrower

0..* 0..*

Item

0..1

0..*

Reservation

0..*

0..*

Title

0..*

0..*

Dynamic Analysis

• “Borrow Item” use case using SequenceDiagram

• “Add Title” use case using Collaborationdiagram

• “Add Item” using Activity diagram• “Reservation” state diagram

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• “Borrow Item” use case using SequenceDiagram

• “Add Title” use case using Collaborationdiagram

• “Add Item” using Activity diagram• “Reservation” state diagram

Borrow Item: Sequence Diagram

: BorrowerBison : LMS : Borrower

1: findTitle ( )

: Title : LoanTransaction

: Item

2: find ( )

3: findItem ( )4: searchItem ( )

5: identifyBorrower ( )6: findBorrower ( )

7: createLoanTrans ( )

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: BorrowerBison : LMS : Borrower

1: findTitle ( )

: Title : LoanTransaction

: Item

2: find ( )

3: findItem ( )4: searchItem ( )

5: identifyBorrower ( )6: findBorrower ( )

7: createLoanTrans ( )

Add Title: Collaboration Diagram

name, ISBN

: Librarian

: Title

Assuming thatadd title impliesadding an item

: Item

1: create ( )

id

2: setItem ( )ObjId,id

3: addItem ( )

Objid

DB : DB

4: storeTitle ( )

titleObj

5: storeItem ( )

itemObj

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name, ISBN

: Librarian

: Title

Assuming thatadd title impliesadding an item

: Item

1: create ( )

id

2: setItem ( )ObjId,id

3: addItem ( )

Objid

DB : DB

4: storeTitle ( )

titleObj

5: storeItem ( )

itemObj

Add Item: Activity Diagram

c r e a t e I t e m

s e t I t e m

a d d T o T i t l e u p d a t e D a t a b a s e

Title Item Database

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c r e a t e I t e m

s e t I t e m

a d d T o T i t l e u p d a t e D a t a b a s e

Component Diagram

GUI Package+ Lend Window+ Return Window+ Reservation Window+ Maintenance Window

Business Package+ Item+ Loan+ Title+ Borrower information+ Book Title+ Reservation+ Magazine Title

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GUI Package+ Lend Window+ Return Window+ Reservation Window+ Maintenance Window

Business Package+ Item+ Loan+ Title+ Borrower information+ Book Title+ Reservation+ Magazine Title

Analysis, DesignImplementation/programming

• What is the deliverable at the end of theanalysis and design phase?

• One or more class diagrams showing theclasses and the relationships that define theOOD.

• On to OOP: Object-oriented programming.

• What is the deliverable at the end of theanalysis and design phase?

• One or more class diagrams showing theclasses and the relationships that define theOOD.

• On to OOP: Object-oriented programming.

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Problem Solving Using Java

OO Design and Progamming in Java

Identify classes needed Write anapplicationclass

Write anappletclass

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Identify classes needed

Reuse APIclasses

Reuseyour classes

Design newclasses

Write anapplicationclass

Write anappletclass

Create and use objects

Instantiation : Examples

• class FordCar ---- defines a class name FordCar• FordCar windstar; ---- defines a Object reference windStar• windstar = new FordCar(); ---- instantiates a windstar Object

• class HousePlan1 { color….• HousePlan1 blueHouse;• blueHouse = new HousePlan1(BLUE);• HousePlan1 greenHouse = new HousePlan1(GREEN);

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• class FordCar ---- defines a class name FordCar• FordCar windstar; ---- defines a Object reference windStar• windstar = new FordCar(); ---- instantiates a windstar Object

• class HousePlan1 { color….• HousePlan1 blueHouse;• blueHouse = new HousePlan1(BLUE);• HousePlan1 greenHouse = new HousePlan1(GREEN);

Operator new and “dot”

• new operator creates a object and returns areference to that object.

• After an object has been instantiated, you canuse dot operator to access its methods anddata declarations (if you have accesspermissions).

• EX: redRose.bloom(); greenHouse.color

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• new operator creates a object and returns areference to that object.

• After an object has been instantiated, you canuse dot operator to access its methods anddata declarations (if you have accesspermissions).

• EX: redRose.bloom(); greenHouse.color

Elements of a Class

class

header methods data declarations (variables,constants)

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headerbody

variables,constants

statementsmodifiers,type, name

parameters

selection repetition

assignment

others

Class Structure

class

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variablesconstants

methods

Defining Classes• Syntax:• class class_name {• data-declarations• constructors• methods }• Constructors are special methods used for

instantiating (or creating) objects from a class.• Data declarations are implemented using variable

and constant declarations.

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• Syntax:• class class_name {• data-declarations• constructors• methods }• Constructors are special methods used for

instantiating (or creating) objects from a class.• Data declarations are implemented using variable

and constant declarations.

Naming Convention

• Constants: All characters in uppercase, words in theidentifier separated by underscore: EX: MAX_NUM

• Variables, objects, methods: First word all lowercase,subsequent words start with uppercase. EX: nextInt,myPen, readInt()

• Classes: Start with an uppercase letter. EX: Tree, Car,System , Math

• Packages: are formed by set of related classes andpackages.

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• Constants: All characters in uppercase, words in theidentifier separated by underscore: EX: MAX_NUM

• Variables, objects, methods: First word all lowercase,subsequent words start with uppercase. EX: nextInt,myPen, readInt()

• Classes: Start with an uppercase letter. EX: Tree, Car,System , Math

• Packages: are formed by set of related classes andpackages.

A complete example

• Problem Statement: You have been hired toassist in an secret encryption project. In thisproject each message (string) sent out isattached to a randomly generated secret code(integer) between 1 and 999. Design anddevelop an application program in Java tocarry out this project.

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• Problem Statement: You have been hired toassist in an secret encryption project. In thisproject each message (string) sent out isattached to a randomly generated secret code(integer) between 1 and 999. Design anddevelop an application program in Java tocarry out this project.

Identify Objects

• There are two central objects:– Message– Secret code

• Is there any class predefined in JAVA API thatcan be associated with these objects? Yes ,– “string” of java.lang and “Random” of java.util

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• There are two central objects:– Message– Secret code

• Is there any class predefined in JAVA API thatcan be associated with these objects? Yes ,– “string” of java.lang and “Random” of java.util