Presentación 2 - Objetos II

8/10/2019 Presentacin 2 - Objetos II

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Objects & Classes II

Christian Rodrguez Bustos

Object Oriented Programming

Objects & Classes


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Agenda

Objects & Classes

User definedtypes

Last ClassActivity

ModelingClasses

Working withlist of objects


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Data redundancy & Data integrity

Objects as attributes

User defined types


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Do you remember the Student Class?

Attribute Type

Id Long

User String

First Name String

Last Name String

Birth Date Date

Group Taught int

Objects & Classes


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Data redundancy !!!

Objects & Classes

Data redundancy !!!

All students are linked

to different groups

Student A

Student B

Student C

Group

Number 3

GroupNumber 3

GroupNumber 3


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Changing enviroment

Objects & Classes

The old groupnumber is 3

The new groupnumber is 1003


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Loss of data integrity

Objects & Classes

Loss of dataintegrity

All students are usingdifferent instancesand probably do notwork with an update

object

Student A

Student B

Student C

Group

Number1003

GroupNumber

1003

Group

Number 3


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Objects & Classes

Solution is



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Avoid data redundancy

Objects & Classes

Avoid dataredundancy and

loss of data integrity

All students can use

the same Groupinstance

Student A

Student B

Student C

Group

Number 3


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Class List

Class Definitions

Last Class activity

Objects & Classes


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1. Abstract the model to submit the grades of astudent in the SIA (Classes, behaviors, attributes,etc)

2. Create a Java project in NetBeans or Eclipse

3. Create the Java classes of the proposed model

4. Encapsulate the classes

Last Class activity

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Class Student

Attribute Type

Id Long

User String

First Name String

Last Name String

Birth Date Date

Attends List of Groups

List of User defineobjects can be used

as attributes

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Class Professor

Objects & Classes

Attribute Type

Id Long

User String

First Name String

Last Name String

Birth Date Date

Groups Taught List of Groups


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Class Course

Objects & Classes

Attribute Type

Number Long

Name StringOffered As List of Groups


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Class Grade

Objects & Classes

Attribute Type

Student Student

Group GroupGrade double


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Class Group

Objects & Classes

Attribute Type

Number Long

Days Of Week String Array

Times Of Day String Array

Semester String

Represents Course

Taught By Professor

Attended By List of Student

Issue List of Grades


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UML

UML Class Diagram

Modeling Classes


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Unified Modeling Language(UML) is a standardized

general-purpose modelinglanguage in the field of object-

oriented software

engineering

s a stan ar ze genera -purpose mo e nglanguage

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s a stan ar ze genera -purpose mo e nglanguage

Objects & Classes

There are severaldiagrams in UML for

modeling objectoriented systems

Activity diagramsand class diagrams

are two examples


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UML Class diagram

Objects & Classes

Describes the staticstructure of a systemshowing

Classes: Name

Attributes

Methods

Relationships betweenclasses


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Showing classes

Objects & Classes

Classes can be

shown at differentdetail level


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Showing relationships between classes

Objects & Classes

A Professor teaches one or moreGroups


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Objects & Classes

A Professor teaches one or moreGroups


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Objects & Classes

Multiplicity


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Multiplicity

Objects & Classes

Is the number of objects that participate inthe relationship

0..1 No instances, or one instance (optional,may)

1 Exactly one instance

0..* or * or 0..n Zero or more instances

1..* One or more instances (at least one)


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From model to code

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Objects & Classes


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Array List Basics

Working with list of objects

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Array List Basics

Instantiation

Addingelements

Objects & Classes


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Array List Basics

Obtaining objects

Obtaining list size

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Iterating through Array Lists

Objects & Classes


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1. Abstract the model to submit the grades of a student inthe SIA (Classes, behaviors, attributes, etc)

2. Create a Java project in NetBeans or Eclipse

3. Create the Java classes of the proposed model

4. Encapsulate the classes

Now is your turn for using your model

Objects & Classes


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[Barker] J. Barker, Beginning Java Objects: From Concepts To

Code, Second Edition, Apress, 2005.

[Deitel] H.M. Deitel and P.J. Deitel, Java How to Program, PrenticeHall, 2007 - 7th ed.

[Sierra] K. Sierra and B. Bates, Head First Java, 2nd Edition,O'Reilly Media, 2005.

References

Objects & Classes

Documents

Presentación 2 - Objetos II