INTRODUCTION TO JAVAData Structure: Java Programming 1

Min ChenSchool of Computer Science and Engineering

Seoul National University

Content

Overview of Java Integrated Development Environment

(IDE) Install Java SE Introduction to Eclipse Setup your IDE in Windows Start a new Java Project

Object-Oriented Programming Concept of Class Method in Class Class in Java Programming

Overview of Java

Began as an internal project in 1990 Named “Oak” first Sun Microsystem Providing an alternative to the C++/C

Re-target Java to Internet in 1994 Versions

Java Card Java ME (Micro Edition) Java SE (Standard Edition) Java EE (Enterprise Edition)

Features of Java

Object-Oriented Programming Language

Write Once, Run Anywhere Java Virtual Machine (VM)

Machine Code

Java VM

Java Binary Files

(.class)

Java Code (.java)

Compiler

Java Developer’s Kit (JDK)

RuntimeInterpreting

Install Java SE JDK Website:

http://www.java.com/en/download/manual.jsp

IDE: Eclipse

A powerful IDE for Java development As Microsoft Visual C++ for C++/C

Development Totally Free of Use !!! A large number of Plug-in

Enable C++ development Enable Website Design … …

Integrated Development Environment

Eclipse: Download Website:

http://www.eclipse.org/downloads/

Start Eclipse Steps

1. Extract the zip file into your hard disk2. Double click to run “eclipse.exe”3. Select your workspace directory

Start a new Java Project

Writing Code for HelloWorld

public static void main(String args[]){ System.out.print("Hello World in Java!");}

HelloWorld: Result

Object-Oriented Programming Process-Oriented Programming

Focus on a flow process Separates the concerns of data structures and

the concurrent processes that act upon them Object-Oriented Programming

Uses "objects" – data structures consisting of datafields and methods together with their interactions – to design applications

Feature Information hiding, Data abstraction,

Encapsulation, Modularity, Polymorphism, Inheritance

Object-Oriented Programming Example: Gobang Game (five-in-a-

row)Start

Black Turn

Draw chessboard

Black Win ?

End

White TurnDraw

chessboard

White Win ?

Y

N

Y

N

Process-OrientedProgramming:

Object-OrientedProgramming:

ChessboardSystem

JudgmentSystem

White Player

Black Player

Process-Oriented Programming Focus on the flow of the work The basis of programming

if… else… Loop Function

Recursion

Function

Usually called “Method” in Java

public int larger (int a, int b) { if(a>b) return a; else return b; }

Type of Return Value

Name of the method

Parameters for the method

Privilege of the method

Recursion

Fibonacci Number 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144,

…

1

1

0

,

,

,

)2()1(

1

0

)(

x

x

x

xfxf

xf

The function calls itself

Towers of Hanoi

Concept of Class

Example 1

Name: Bill Gates

Gender: Male

Age: 54

Born: U.S.

Company:

Microsoft

Products:

Windows, Office…

Name: Steve Jobs

Gender:

Male

Age: 54

Born: U.S.

Company:

Apple Inc.

Products:

Mac, iPod, iPhone…

CEOsName

Gender

AgePlace of

BirthCompany

Products

Attribute

Concept of Class (cont.)

Example 2Name: 박지성Gender: Male

Age: 28

Born: Korea

Employer:

Man. United

Sports: Football

League: Premier

Name: Yao Ming

Gender: Male

Age: 29

Born: China

Employer:

Rockets

Sports: Basketball

League: NBA

SportsmenName

Gender

AgePlace of

BirthEmployer

Sports

League

Name: 이병헌Gender: Male

Age: 39

Born: Korea

School: 중앙대Drama: All In,

Iris

Name: 김태희Gender: Female

Age: 29

Born: Korea

School: 서울대Drama: Love

Story in Harvard, Iris

Concept of Class (cont.)

Example 3

StarsName

Gender

AgePlace of

BirthSchool

Drama

Inheritance of Class

Higher Abstract

CEOsName

Gender

AgePlace of

BirthCompany

Products

SportsmenName

Gender

AgePlace of

BirthEmployer

SportsLeague

StarsName

Gender

AgePlace of

BirthSchool

DramaCEOs

Company

Products

SportsmenEmployer

SportsLeague

StarsSchool

Drama

PeopleName

Gender

AgePlace of

Birth

Superclass

Subclass

Subclass will inherit most of the attributes of his superclass

Method in Class

A class is not just a collection of data (we call it attribute), but also a collection of methods

Method As the function in C++/C Define procedure with input and output

Example: People

Think() Eat() Sleep()

Method Inheritance

Methods also can be inherited

HumanThink ( )Talk ( )Love ( )

AnimalsEat( )

Sleep( )

CreaturesSurvive( )

Plansphotosynthesi

s( )

Multiple Level Inheritance is allowed

Overwrite of Methods

So how about the situation below ?

CircleCenterRadiusDraw( )

ShapeDescribe

( )Draw( )

Circle c = new Circle(); c.Draw();

Overload of Methods

Can we have two methods with the same name but different parameters in one class ?

public void get() { System.out.print(“No parameters!”); }

public void get(int par) { System.out.print(“Has parameter of ”+ par); }

Overload ol= new Overload(); ol.get(); ol.get(32);

Public Class Overload

No parameters!Has parameter of 32

Summary of Class

Consist of Attributes and Methods Represents a collection of data and

functions which have relationship to each other

Other features Information hiding Data abstraction Encapsulation Modularity Polymorphism Inheritance

Class in Java Programming

Personally, I classify the Classes in Java Programming into two types: Entrance Class (Project Class)

With main method in the Class The entrance and control center of the

whole program Accessories Class

Provide functional part Call in the main function to create

instance

HelloWorld.java is an Entrance Class

The method in Accessories Class being called should be public!

Example CEO Class

Constructed Function:Run when the object is

initiated

Define the attributes for

Class CEO

Set to be public so that the function in CEO can be called in

other Class

Example (cont.) HelloWorld Class

Create an instance (steve)

of Class CEO

Reset the name of the instance by the method setName in

Class CEO

Get the name of the instance by the

method getName in Class CEO

Example Result

The system print out:

Hello World in Java!My name is Steve Jobs

Thank you