lecture note: java programming 1 dept. of mis, kwangwoon university >>> introduction java...

Lecture Note: Java Programming 1 Dept. of MIS, Kwangwoon University

>>> Introduction

Java 소개

Java 개요Sample Programs

객체지향 프로그래밍 개념환경 설정 및 명령어


>>> Introduction

Java 개요• Definition

– A general-purpose, high-level, object-oriented programming language developed by Sun Microsystems. (http://java.sun.com)

– Originally called OAK ("Green Team")

• Java 의 특성– Object-oriented

– Platform-independent (Virtual Machine; portability)

– Easy; Simplified; (no pointer, automatic garbage collection, single inheritance, ..)

– compiled/interpreted, robust, secure, multi-threaded, distributed, ...

• Compile/Execution

javac컴파일러

SourceCode

ByteCode

java

인터

프리

터

JITCompiler

MachineCode

생성 / 실행

.java .class

JVM

JRE

API classesfiles, ...

브라

우저

, or

appl

etvi

ewer interpret


>>> Introduction

Java 개요 (Cont.)• 자바의 버젼

– Java 1.1.5: announced in 1997, improved user interface, event processing, ...

– Java2: beta-testing in 1997; Released in late 1998 (JDK 1.2); Swing, Drag&Drop, improved sound utility, ...

– Java2: SDK Standard Edition 1.3 (2000), 1.4 (2002), J2SE 5.0 (tiger), J2SE6.0(mustang), …

– http://java.sun.com

• 자바 툴– Kawa, Eclipse, ..

– Symantec Visual Cafe, Borland JBuilder, SuperCede, Rogue Wave JFactory, Natural Intelligence Roaster, Metro Works Code Warrior, SunSoft Java Workshop, …

• Related Terms– http://webopedia.internet.com/

– applet, AWT, bytecode, CGI, HotJava, interpreter, JAR, JavaBeans, JavaScript, JDBC, JDK, Jini, JIT, JNI, picoJava, Python, RMI, Smalltalk, thin client, virtual machine, JavaOS, JavaRing, JavaCard, EJB, Java Station, …


>>> Introduction

Java 2 Standard Edition• Java 2 Standard Edition includes

– Java runtime environment: • A Java virtual machine for the platform you choose

• Java class libraries for the platform you choose

– Java compiler

– Java class library (API) documentation (as a separate download)

– Additional utilities, such as utilities for creating Java archive files (JAR files) and for debugging Java technology programs

– Examples of Java technology programs


>>> Introduction

Product Life Cycle• Seven Stages

– Analysis: investigate a problem and determine its scope and major components

– Design: create blueprints (specs) for components that will be developed

– Development

– Testing: unit tests (individually) and integrated test (together)

– Implementation: ship a product, making the product available to customers

– Maintenance

– End-of-life (EOL)


>>> Introduction

A Sample Program• a Java program

– source program• .java

• text file format

• pico, vi, emacs, ... in Unix; notepad, edit, ... in Windows

class HelloWorld {

// 주석 부분 public static void main (String args[]){

String msg = "World";

System.out.print("Hello ");System.out.println(msg);

}}

– javac HelloWorld.java• creates HelloWorld.class

– java HelloWorld

#include <stdio.h>

char msg[ ]={‘W’,‘o’,‘r’,‘l’,‘d’};/* comments here */main (int argc, char **argv) {

printf(“Hello ”); printf(“%s\n”, msg);}

참고 : C program


>>> Introduction

Object-oriented Programming• Program

– a set of classes and interactions among them

– not procedure-oriented

• Class– a framework for objects (or instances) of similar characteristics

– properties (or, attributes, status variables)

– behavior (or, method, function)• retrieve/update the attribute values of instances, execute an action, etc

– Class example: Student, Employee, Vehicle, Truck, ...

• Example: a monster, called Jabberwock, in a storybook– Making a class for Jabberwork : a simplest form

class Jabberwock { }

– Attributes• color (orange, yellow, ...), sex (m, f), status (full, hungry), …

– Behavior• get angry, cool down, eat a peasant, skip a meal, take a rest, …


>>> Introduction

Jabberwock 예제• 속성 추가

class Jabberwock {String color; // 표준 클래스

String sex;boolean hungry; // true 또는 false 값

}

• Method 추가 : 먹이주기void feedJabberwock( ) {

if (hungry == true) {

System.out.println("Yum -- a peasant!");

hungry = false;

} else

System.out.println("No, thanks -- already ate.");

}


>>> Introduction

Jabberwock 예제 (Cont.)• Method 추가 : 속성 보여주기

void showAttributes( ) {

System.out.println ("This is a " + sex + " " + color + " jabberwock.");

if (hungry == true)

System.out.println("The jabberwock is hungry.");

else

System.out.println("The jabberwock is full.");

}


>>> Introduction

Jabberwock 예제 (Cont.)• 클래스 완성 (?)

class Jabberwock { String color; String sex; boolean hungry;

void feedJabberwock() { if (hungry == true) { System.out.println("Yum -- a peasant!"); hungry = false; } else System.out.println("No, thanks -- already ate."); }

void showAttributes() { System.out.println("This is a " + sex + " " + color + " jabberwock."); if (hungry == true) System.out.println("The jabberwock is hungry."); else System.out.println("The jabberwock is full."); }

}


>>> Introduction

Jabberwock 예제 (Cont.)• % javac Jabberwock.java

% java JabberwockIn class Jabberwock: void main (String argv[ ]) is not defined

• 방안– main( ) 메쏘드에서 Jabberwock 클래스를 이용하도록 한다

• main ( ) 메쏘드를 Jabberwock 클래스에 추가 , or • main( ) 메쏘드를 갖는 새로운 클래스를 만든다

public static void main (String arguments[]) { Jabberwock j = new Jabberwock( ); // 새로운 객체 생성 j.color = "orange"; j.sex = "male"; j.hungry = true; // 객체 이용 System.out.println("Calling showAttributes ..."); j.showAttributes( ); // 객체 이용 System.out.println("-----"); System.out.println("Feeding the jabberwock ..."); j.feedJabberwock( ); System.out.println("-----"); System.out.println("Calling showAttributes ..."); j.showAttributes( ); System.out.println("-----"); System.out.println("Feeding the jabberwock ..."); j.feedJabberwock( ); }


>>> Introduction

Java Applet• Java Application 과 Java Applet

– main class

• javac Hello.java

• appletviewer hello.htm 실행 , 또는 웹 브라우저로 hello.html 열기import java.awt.*;import java.applet.*;Import java.util.*;

public class Clock extends Applet { private String greeting[] = { "Hello, world" };

public void paint(Graphics g) { g.drawString(greeting[0], 25, 25); }}

<html><head><title>Hello</title></head><body><applet code=Hello.class width=250 height=250></applet></body></html>

Hello.java Hello.html


>>> Introduction

Java 객체지향 프로그래밍 (Cont.)

• 상속성 (Inheritance)

– 한 클래스가 다른 클래스로부터 속성과 메쏘드를 물려받는 성질

– superclass; subclass; inheritance hierarchy;

– Object 클래스

– method overriding

– subclassing

• 패키지 (Package)

– 관련된 클래스와 인터페이스의 그룹핑 • 인터페이스 (Interface): 추상 메쏘드만 갖는 특별한 형태의 클래스

– java.lang 패키지 : 표준 java 클래스

– 다른 클래스의 참조• import java.awt.Color 또는 import java.awt.*

• import java.applet.*


>>> Introduction

Applet 예제 2: Palindrome • 어떤 문장을 display 하는 애플릿 프로그램 작성• 애플릿 정의

public class Palindrome extends java.applet.Applet {

}– 모든 애플릿 클래스는 public 선언

• 폰트 객체 생성Font f = new java.awt.Font("TimesRoman", Font.BOLD, 36);

• 애플릿이 상속 받는 메쏘드– 애플릿 실행 준비 , 마우스 입력 대응 , 애플릿 표시 , 실행 종료용 , ...

– paint ( ) 메쏘드의 재정의 (overriding)

public void paint(Graphics screen) { // Learn later about Graphics class screen.setFont(f); screen.setColor(Color.red); screen.drawString("Go hang a salami, I'm a lasagna hog.", 5, 40);

}


>>> Introduction

Subclassing 예제 : Palindrome • a complete program

import java.awt.Graphics;import java.awt.Font;import java.awt.Color;import.applet.*

public class Palindrome extends Applet { Font f = new Font("TimesRoman", Font.BOLD, 36);

public void paint(Graphics screen) { screen.setFont(f); screen.setColor(Color.red); screen.drawString("Go hang a salami, I'm a lasagna hog.", 5, 40); }}

• <APPLET CODE="Palindrome.class" WIDTH=600 HEIGHT=100></APPLET>


>>> Introduction

환경 설정• JDK 설치 디렉토리

– bin

• javac, java, appletviewer, jar, javah, javap, javadoc, ...

– demo, jre, include, lib, …

• 명령어 경로 지정 (path 변수 )

– javac, java, appletviewer, ...

– Windows 98 예 • autoexec.bat 화일에 set path=%path%; c:\jdk1.4\bin 추가

• 실행 sysedit

– NT/2000, XP 예 • 설정 제어 시스템 고급 탭 에서 path 변수값 변경

– Unix 예 • .cshrc (or .tcshrc) 화일에 set path=($path /usr/local/java/bin) 추가


>>> Introduction

환경 설정 (Cont.)

• 클래스 경로 지정 (CLASSPATH 변수 )

– JDK1.2 이전 버젼의 경우

• set CLASSPATH=.;c:\jdk1.1.7\lib\classes.zip [Windows 의 path 설정참조 ]

• setenv JAVA_HOME /usr/local/jdk

setenv CLASSPATH .:$JAVA_HOME/lib/classes.zip [Unix]

– JDK1.2 이후 버전의 경우

• CLASSPATH 변수를 두지 않거나 또는 . 만 포함해도 됨

– refer to the readme file or installation documents from java.sun.com

• explore.kwangwoon.ac.kr 에 홈페이지 만들기

– Refer to http://explore.kwangwoon.ac.kr

– public_html directory

– explore 서버의 환경은 ? (JDK 버젼 ? 명령어 위치 ? 환경변수 설정 ? ...)


>>> Introduction

환경 설정 (Cont.)• Basic Unix commands

– ls [-al] [files] ---- list information of files

– more filename ---- display the content of a file ( 긴 화일일때 Space 키 , b, q, /, ..)

– cd [path] ---- change the current directory ( 절대 / 상대 경로 )

– mkdir dirname ---- create a directory ( 디렉토리의 삭제 rmdir, 화일삭제 rm )

– chmod [ugo][rwx] file ------ change the permission mode of a file

– pico filename

– vi [filename] ----- cursor-based screen editor• 이동 : h, j, k, l, ^f, ^b, ^u, ^d

• 입력 / 변경 : i, a, I, A, c, cw, cc, ( 입력모드 종료시 ESC 키 필요 )

• 삭제 : x, dw, dd, 5x, 5cw, 5dd ( 붙여넣기 p 직전명령취소 u 직전명령반복 . )

• 저장 / 종료 : :w, ZZ, :wq!, :q!

– man 명령어 ---- on-line 매뉴얼– logout ( 또는 exit)


>>> Introduction

javac 컴파일러• Compiles Java source code into Java bytecodes that can then be used by the

java interpreter, Web browsers, and appletviewers.

• 용법javac [options] [source files] [@sourcelist]

• .java extension for source file names

• Classname.java, if the class is public or is referenced from another source file.

• Generates .class file for every class defined in each source file

• examplesjavac MyProgram.java javac -classpath .:/home/avh/classes:/usr/local/java/classes MyProgram.java javac -d /home/avh/classes MyProgram.java (package 위치 지정 )

• 기타 옵션-g for debugging (jdb)

-encoding … source files encoding name (e.g., KSC5601, SJIS, …)

• man javac


>>> Introduction

java 인터프리터 & javap

• 용법java [options] class 이름 [argument ...]

option: -Dproperty=value

• JIT compiler– Sun Microsystems, Asymetrix SuperCede VM, Kaffe bytecode interpreter, Micr

osoft SDK 2.0 VM, Symantec JIT compiler, ...

– 강의노트의 JITintro.htm 문서 참조

• To disable or override the default JIT compiler – setenv JAVA_COMPILER NONE ( 또는 다른 이름 )

– % java -Djava.compiler=none class 이름

• javap– disassemble the class files

– fields, methods, variables,

– De-compile of bytecode is possible (source is disclosed)


>>> Introduction

jar• jar - Java archive tool

– a Java application that combines multiple files into a single JAR archive file.

– also a general-purpose archiving and compression tool, based on ZIP and the ZLIB compression format.

• SYNOPSIS

jar [ -c ] [ -f ] [ -t ] [ -v ] [ -x file ]

[ manifest-file ] destination input-file [ input-files ]

• example% jar cvf myJarFile *.class

• Manifest file – meta-information about the archive

– automatically generated by the jar tool

– always the first entry in the jar file

– by default, META-INF/MANIFEST.INF

• c.f., tar command in Unix

• % man jar


>>> Introduction

기타 명령어• appletviewer URL_of_HTML

• jdb– dbx, gdb like command-line debugger

• javah– generates C header and source files that are needed to implement native method

s.

• javadoc– Java API Documentation Generator

– parses the declarations and comments in a set of Java source files and produces a set of HTML pages describing, by default, the public and protected classes, interfaces, constructors, methods, and fields.

• javakey– Java security tool which is primarily used to generate digital signatures for archi

ve files.

• javaverify


>>> Introduction

Some Tips

• Java is case-sensitive

• Hello.java.txt when editing in notepad

• 여러 클래스로 구성된 화일의 컴파일과 실행– javac file1.java file2.java ...

– java class_file_having_main_function

• public class– at most one for each file

– the same file name as the class name (except suffix)

• naming convention– MyClassName

– System.out.println

– myFirstMethod


>>> Introduction

연 습 Unix 환경과 Windows 환경에서 각각 다음 내용을 실시하라

- 자신의 홈 디렉토리 ( 또는 ' 내문서 ') 아래에 java_work 디렉토리를

생성하고

- Jabberwock 와 Palindrome 클래스를

작성하여 실행시켜보라 .

Hello.java 의 화일명을 hello.java 로

바꿔서 컴파일하면 ? 또 , Hello.html 에

애플릿 태그가 여러 개 있을 때 , appletviewer Hello.html 의 결과는 ?

jar 명령을 이용하여 압축저장 / 내용보기 / 추출 등을 연습해보라 .

javap, javaverify 등의 각 명령어들을 이용해보고 , Unix 에서 man

명령을 이용하여 on-line 매뉴얼을 살펴보라 .

Java Application Java Applet

Windows DOS browser or appletviewerWindows Kawa

Unix browser

UnixWindows


>>> Introduction

과제 #1

[ 과제 1-2] ‘ 시계’라고 하는 클래스를 생각해보라 . ( 이름 추가할 것 )

1. 어떤 attribute 들이 있겠는가 ? (3 개 이상 ) 그리고 각 attribute 의 가능한

값은 무엇인가 ?

2. 어떤 method 들이 있겠는가 ? (3 개 이상 )

( 날짜 출력하는 프로그램 , Applet+Application, bollen charged charged=false

d, 출력불가 메시지 출력 , 시계 color = )

Due: 다음 주 – URL 강의게시판에 등록 ( 과제제출 – 애플릿만 )

소스코드와 실행스샷은 첨부로 (DOC 로 몰아서 ~!) (9/17 까지 )

lecture note: java programming 1 dept. of mis, kwangwoon university >>> introduction java...

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