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Pemrograman Berorientasi Obyek

(OOP : Object Oriented Programming)

JAVA
http://java.sun.com/


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Object Orientation involving encapsulation,

inheritance, polymorphism, and abstraction, is animportant approach in programming and program

design. It is widely accepted and used in industry and

is growing in popularity in the first and second

college-level programming courses.


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ClassName

- attribute_declaration

+ constructor_declaration+ method_declaration

Visibility shown as :

+ public

private

# protected

UML diagram


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The Solution

1. public class MyDate {

2. private int day;

3. private int month;

4. private int year;

5. public int getDay() {

6. return day;

7. }

8. public int getMonth() {

9. return month;

10. }11. public int getYear() {

12. return year;

13. }

14. public void setDay(int d) {

15. day = d;

16. }17. public void setMonth(int m) {

18. month = m;

19. }

20. public void setDay(int y) {

21. year = y;

22. }23.}


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Some other reasons to move on

to Java:

Platform-independent software Relatively easy graphics and GUI

programming

Lots of library packages

Free compiler and IDEs


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Java Programming Styles(1)

Packages:

Package names are entirely in lower case.

Package name should start with the web domainname reversed

Examples:package com.sun.java.lang;

package edu.nmsu.is.us.sp;

Files:

The file name must have the same base name as thename of the public class defined in the file.

Example: If you have a public class named RecordList, the file

containing this class should be named RecordList.java


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Classes and Interfaces:

Use meaningful identifiers for classes ,and interfaces.

Capitalize each word contained in aclass identifier name.

No underscores.

Examples:public class RecordList {}

public interface PanelFace {}


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Variables:

Use meaningful identifiers for variables.

Capitalize each word contained in a name of avariable except the first word.

Use nouns to identify variables as possible.

For boolean variables, use identifirs that are likequestions.

Use all-caps indentifiers for constants.

Examples:int number;

String myName;

boolean isValid;

final int CODE = 707;


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Methods:

Use meaningful identifiers for methods.

Capitalize each word contained in a name of amethod except the first word.

Use verbs to identify methods as possible.

For the methods dealing with objects properties,start the method identifier with get or set.

If the method returns boolean use is or are

instead of get to name this method. Examples:

private boolean paint()

boolean isObjectValid()

Font getFont()

void setFont(Font f)


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General Considerations: Use three-space indentation style. Example

if(num < 10)

{

System.out.println(Not Enough);}

Use comments to mark the beginning and the end of blocks

Use three-line style to comment your code. Use either one of:

// /*

// This part is to or * This part is to

// */

Use empty lines to increase the readability of your code

Use spaces between the operators such as +, -, =, and theoperands. Example:

c = a + b;


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Some other reasons to move on

to Java: Colleges are teaching it

Companies are using it

Students want it

(Teachers welcome it... ;)

(Programmers drink it... :)


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What are OOPs claims to fame?

Better suited for team development

Facilitates utilizing and creating reusable

softwarecomponents

Easier GUI programming

Easier program maintenance


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OOP


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Abstraction

... relevant to the given project (with an

eye to future reuse in similar projects).

Abstraction means ignoring irrelevant

features, properties, or functions and

emphasizing the relevant ones...

Relevant to what?


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Encapsulation

Encapsulation means that all data members

(fields) of a class are declared private. Some

methods may be private, too.The class interacts with other classes (called

the clientsof this class) only through the

classs constructors and public methods.Constructors and public methods of a class

serve as the interfaceto classs clients.


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public abstract class Foot{

private static final int footWidth = 24;

private boolean amLeft;

private int myX, myY;

private int myDir;

private boolean myWeight;

// Constructor:

protected Foot(String side, int x, int y, int dir)

{

amLeft = side.equals("left");

myX = x;

myY = y;

myDir = dir;

myWeight = true;

}

Continued

All fields areprivate


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Encapsulation ensures that

structural changes remain local Changes in the code create software

maintenance problems

Usually, the structure of a class (as defined

by its fields) changes more often than the

classs constructors and methods

Encapsulation ensures that when fields

change, no changes are needed in other

classes (a principle known as locality)


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Inheritance

A class can extend another class,

inheriting all its data members and

methods while redefining some of themand/or adding its own.

Inheritance represents the is a

relationship between data types. Forexample: a FemaleDanceris a

Dancer.


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Inheritance Terminology:

public class FemaleDancer extendsDancer{

...

}

subclass

or

derived class

superclass

or

base class

extends


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Polymorphism

Polymorphism ensures that the

appropriate method is called for an

object of a specific type when the objectis disguised as a more general type.

Good news: polymorphism is already

supported in Javaall you have to dois use it properly.


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Polymorphism (contd)

Situation 1:

A collection (array, list, etc.) contains

objects of different but related types, all

derived from the same common base

class.

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