Introduction Java Java Sample Programs Lecture Note Java

>>> Introduction Java 소개 Java 개요 Sample Programs 객체지향 프로그래밍 개념 환경 설정 및 명령어 Lecture Note: Java Programming Dept. of MIS, Kwangwoon University

>>> 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") • Java의 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 javac 컴파일러 . java Lecture Note: Java Programming java 브라우저, or appletviewer 인터프리터 Source Code JRE Byte Code. class 2 API classes files, . . . JVM interpret JIT Compiler Machine Code 생성 / 실행 Dept. of MIS, Kwangwoon University

>>> Introduction Java 개요 (Cont. ) • 자바의 버젼 – Java 1. 1. 5: announced in 1997, improved user interface, event processing, . . . – Java 2: beta-testing in 1997; Released in late 1998 (JDK 1. 2); Swing, Drag&Drop, improved sound utility, . . . – Java 2: SDK Standard Edition 1. 3 (2000), 1. 4 (2002), J 2 SE 5. 0 (tiger), J 2 SE 6. 0(mustang), … – http: //java. sun. com • 자바 툴 – Kawa, Eclipse, . . – Symantec Visual Cafe, Rogue Wave JFactory, Metro Works Code Warrior, Borland JBuilder, Super. Cede, Natural Intelligence Roaster, Sun. Soft Java Workshop, … • Related Terms – http: //webopedia. internet. com/ – applet, AWT, bytecode, CGI, Hot. Java, interpreter, JAR, Java. Beans, Java. Script, JDBC, JDK, Jini, JIT, JNI, pico. Java, Python, RMI, Smalltalk, thin client, virtual machine, Java. OS, Java. Ring, Java. Card, EJB, Java Station, … Lecture Note: Java Programming 3 Dept. of MIS, Kwangwoon University

>>> 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 Lecture Note: Java Programming 4 Dept. of MIS, Kwangwoon University

>>> 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) Lecture Note: Java Programming 5 Dept. of MIS, Kwangwoon University

>>> Introduction A Sample Program • a Java program – source program – javac Hello. World. java • . java • creates Hello. World. class • text file format – java Hello. World • pico, vi, emacs, . . . in Unix; notepad, edit, . . . in Windows class Hello. World { #include <stdio. h> // 주석 부분 public static void main (String args[]){ String msg = "World"; char msg[ ]={‘W’, ‘o’, ‘r’, ‘l’, ‘d’}; /* comments here */ main (int argc, char **argv) { System. out. print("Hello "); System. out. println(msg); } } 참고: C program } Lecture Note: Java Programming printf(“Hello ”); printf(“%sn”, msg); 6 Dept. of MIS, Kwangwoon University

>>> 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, … Lecture Note: Java Programming 7 Dept. of MIS, Kwangwoon University

>>> Introduction Jabberwock 예제 • 속성 추가 class Jabberwock { String color; // 표준 클래스 String sex; boolean hungry; // true 또는 false 값 } • Method 추가: 먹이주기 void feed. Jabberwock( ) { if (hungry == true) { System. out. println("Yum -- a peasant!"); hungry = false; } else System. out. println("No, thanks -- already ate. "); } Lecture Note: Java Programming 8 Dept. of MIS, Kwangwoon University

>>> Introduction Jabberwock 예제 (Cont. ) • Method 추가: 속성 보여주기 void show. Attributes( ) { 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. "); } Lecture Note: Java Programming 9 Dept. of MIS, Kwangwoon University

>>> Introduction Jabberwock 예제 (Cont. ) • 클래스 완성 (? ) class Jabberwock { String color; String sex; boolean hungry; void feed. Jabberwock() { if (hungry == true) { System. out. println("Yum -- a peasant!"); hungry = false; } else System. out. println("No, thanks -- already ate. "); } } void show. Attributes() { 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. "); } Lecture Note: Java Programming 10 Dept. of MIS, Kwangwoon University

>>> Introduction Jabberwock 예제 (Cont. ) • % javac Jabberwock. java % java Jabberwock In 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 show. Attributes. . . "); j. show. Attributes( ); // 객체 이용 System. out. println("-----"); System. out. println("Feeding the jabberwock. . . "); j. feed. Jabberwock( ); System. out. println("-----"); System. out. println("Calling show. Attributes. . . "); j. show. Attributes( ); System. out. println("-----"); System. out. println("Feeding the jabberwock. . . "); j. feed. Jabberwock( ); } Lecture Note: Java Programming 11 Dept. of MIS, Kwangwoon University

>>> Introduction Java Applet • Java Application과 Java Applet – main class • javac Hello. java • appletviewer hello. htm 실행, 또는 웹 브라우저로 hello. html 열기 import java. awt. *; import java. applet. *; Import java. util. *; public class Clock extends Applet { private String greeting[] = { "Hello, world" }; public void paint(Graphics g) { g. draw. String(greeting[0], 25); } } Hello. java Lecture Note: Java Programming <html> <head> <title>Hello</title> </head> <body> <applet code=Hello. class width=250 height=250> </applet> </body> </html> Hello. html 12 Dept. of MIS, Kwangwoon University

>>> 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. * Lecture Note: Java Programming 13 Dept. of MIS, Kwangwoon University

>>> Introduction Applet 예제 2: Palindrome • 어떤 문장을 display하는 애플릿 프로그램 작성 • 애플릿 정의 public class Palindrome extends java. applet. Applet { } – 모든 애플릿 클래스는 public 선언 • 폰트 객체 생성 Font f = new java. awt. Font("Times. Roman", 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. set. Font(f); screen. set. Color(Color. red); screen. draw. String("Go hang a salami, I'm a lasagna hog. ", 5, 40); Lecture Note: Java Programming 14 Dept. of MIS, Kwangwoon University

>>> 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("Times. Roman", Font. BOLD, 36); public void paint(Graphics screen) { screen. set. Font(f); screen. set. Color(Color. red); screen. draw. String("Go hang a salami, I'm a lasagna hog. ", 5, 40); } } • <APPLET CODE="Palindrome. class" WIDTH=600 HEIGHT=100> </APPLET> Lecture Note: Java Programming 15 Dept. of MIS, Kwangwoon University

>>> Introduction 환경 설정 • JDK 설치 디렉토리 – bin • javac, java, appletviewer, 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: jdk 1. 4bin 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 Lecture Note: Java Programming 16 Dept. of MIS, Kwangwoon University

>>> Introduction 환경 설정 (Cont. ) • 클래스 경로 지정 (CLASSPATH 변수) – JDK 1. 2 이전 버젼의 경우 • set CLASSPATH=. ; c: jdk 1. 1. 7libclasses. zip [Windows의 path 설정참조] • setenv JAVA_HOME /usr/local/jdk setenv CLASSPATH. : $JAVA_HOME/lib/classes. zip [Unix] – JDK 1. 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? . . . ) Lecture Note: Java Programming 17 Dept. of MIS, Kwangwoon University

>>> 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, 5 x, 5 cw, 5 dd (붙여넣기 p 직전명령취소 u 직전명령반복. ) 저장/종료: : w, ZZ, : wq!, : q! – man 명령어 ---- on-line 매뉴얼 – logout (또는 exit) Lecture Note: Java Programming 18 Dept. of MIS, Kwangwoon University

>>> Introduction javac 컴파일러 • Compiles Java source code into Java bytecodes that can then be used by the java interpreter, Web browsers, and appletviewers. • 용법 javac [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 examples javac My. Program. javac -classpath. : /home/avh/classes: /usr/local/java/classes My. Program. javac -d /home/avh/classes My. Program. java (package 위치 지정) • 기타 옵션 -g for debugging (jdb) -encoding … source files encoding name (e. g. , KSC 5601, SJIS, …) • man javac Lecture Note: Java Programming 19 Dept. of MIS, Kwangwoon University

>>> Introduction java 인터프리터 & javap • 용법 java [options] class이름 [argument. . . ] option: -Dproperty=value • JIT compiler – Sun Microsystems, Asymetrix Super. Cede VM, Kaffe bytecode interpreter, Microsoft 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 class이름 • javap – disassemble the class files – fields, methods, variables, – De-compile of bytecode is possible (source is disclosed) Lecture Note: Java Programming 20 Dept. of MIS, Kwangwoon University

>>> 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 my. Jar. File *. 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 Lecture Note: Java Programming 21 Dept. of MIS, Kwangwoon University

>>> 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 methods. • 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 archive files. • javaverify Lecture Note: Java Programming 22 Dept. of MIS, Kwangwoon University

>>> Introduction Some Tips • Java is case-sensitive • Hello. java. txt when editing in notepad • 여러 클래스로 구성된 화일의 컴파일과 실행 – javac file 1. java file 2. 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 – My. Class. Name – System. out. println – my. First. Method Lecture Note: Java Programming 23 Dept. of MIS, Kwangwoon University

>>> Introduction 연습 ü Unix 환경과 Windows 환경에서 각각 다음 내용을 실시하라 - 자신의 홈 디렉토리 (또는 '내문서') 아래에 java_work 디렉토리를 생성하고 Java Application - Jabberwock와 Palindrome클래스를 Windows DOS 작성하여 실행시켜보라. ü Hello. java의 화일명을 hello. java로 Java Applet Windows Kawa browser or appletviewer Unix browser Unix Windows 바꿔서 컴파일하면? 또, Hello. html에 애플릿 태그가 여러 개 있을 때, appletviewer Hello. html의 결과는? ü jar 명령을 이용하여 압축저장/내용보기/추출 등을 연습해보라. ü javap, javaverify 등의 각 명령어들을 이용해보고, Unix에서 man 명령을 이용하여 on-line 매뉴얼을 살펴보라. Lecture Note: Java Programming 24 Dept. of MIS, Kwangwoon University