Java Programming (Part 1) Introduction

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Java Programming (Part 1)Introduction

• ???
• http//www.ywdeng.idv.tw
• joseph.deng_at_gmail.com

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????

• Java ????
• Java ????
• ??????Hello Java !
• Java ??????
• ???????
• ???????
• ????
• ????? Java ??
• ????????? Hello Java !

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????

• ??? ?,Java SE6 ????,????,2007?,??
  ACL023000,ISBN 9789861811321
• ??? ?, Java SE 6.0????????,????,2009?,??
  AEL006900 ,ISBN 9789861816104

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Java ????Java ???

• 1995 ??? by Sun Microsystems
• ?? Oak,Project Green,?????????
• ?? James Gosling
• Java ???????
• Java Applet??????????
• JavaScriptNetscape, ????????

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Java ??????????

• ?????? I/O??? Pointer
• ???Java ???????(VM)???,????????????,????? Java
  ??
• ???????????
• API ??,????????,??????
• ??,??? Exception Handling ??
• ????(Multithread)
• ??????

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Java ????Java ????

• Java ?????????????
• ???????????? Java ??,??????? Java ??????????
• ????????(The College Board)???????????????????????
  ,??? Java ???????????

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Java ????Java ???

• JAVA SE(Java Platform, Standard Edition)
• ???????GUI????????
• JAVA EE(Java Platform, Enterprise Edition)
• N-Tier Applications?Web Applications?
• JAVA ME(Java Platform, Micro Edition)
• PDA????Smart Card?

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JAVA ????

• JDK 1.21.4 ?????,?? J2SE(Java 2 Platform,
  Standard Edition)
• J2SE 5.0(Java 2 Platform Standard Edition
  5.0)??JDK??J2SE Development Kit 5.0
• ?Java SE 6(Java Platform, Standard Edition
  6)???JDK6????Java SE Development Kit 6
• ????2????,???6?1.6.0???
• 6?????(Product Version),?1.6.0??????(Developer
  Version)

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Java Platform Edition
??http//thisjava.blogsome.com/2005/03/28/java-tec
hnology/
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Java Platform Products
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Java ????Java ????
??http//www.sun.com/training/certification/java/i
ndex.xml
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JAVA ????

• JDK
• http//java.sun.com
• ???,?? JAVA_HOME ????
• Online Document
• NetBeans
• http//www.netbeans.org
• Eclipse
• http//www.eclipse.org

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??JDK (1)

• JDK Java Development Kit ????
• JRE Java Runtime Environment ????
• ??JRE?????????????
• JDK???????JRE
• ??JDK??????jre????
• JDK?????JRE???JRE???Server?VM(Virtual
  Machine)????

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??JDK (2)
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JDK?????

• ?bin???
• JDK?????
• ?demo???
• ????
• ?jre???
• JDK?????JRE
• ?db???
• Apache Derby???,?Java???????

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JDK?????

• ?lib???
• ???????????Java????
• JDK??????,?????Java?????
• bin?????????,???????(Wrapper)
• ??javac.exe????,?????lib???tools.jar??????

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JDK?????

• src.zip
• Java???API???????????

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?? JAVA_HOME ????

• JAVA_HOME ??????? JDK ?????

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?? Path ???? (1)

• ???javac????
• ???????? Path ????

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?? Path ???? (2)

• Windows???JRE?,??java.exe????C\Windows\System32\?
  ????,??????Path?????????

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?? CLASSPATH ???? (1)

• Java???????????,??????????????????Java??
• ??Path???????????????????(??Windows ?? exe)
• ??classpath???????Java?????????Java??(JVM
  ??class)

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?? CLASSPATH ???? (2)

• JDK 6 ??????????,??JDK??lib??????Java??
• Classpath ????????? JAR ???
• ????????????
• javac -classpath path1path2
• ????????????
• java -classpath path1path2

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?? CLASSPATH ???? (3)
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?? Windows ????????????
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Java ????

• ??????Hello Java !
• Java ??????
• ???????
• ???????
• ????
• ????? Java ??
• ????????? Hello Java !

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??????Hello Java !
public class Hello public static void
main(String args) System.out.println("Hell
o Java !")
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Java ??????

• ???????????(Class)
• Source file ??????? Class ?????,?????????,????
  .java?
• public static void main(String args) ???????
• main method ?????? public static
  void,???????????? class loader ??,??????????,?????
  ?????
• System ?????,out ? stdout,println ????????
• JRE class loader ???? class name ????????

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????

• CD ????(Change Directory)
• CD C\
• DIR ??????(Directory)
• javac ?? JAVA ???(Java Compiler)
• javac Hello.java
• java ?? JAVA
• java Hello

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????? Java ??

• To compile
• javac Hello.java
• To run
• java Hello
• javaw Hello (GUI ?)

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JAVA ????????
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????? Java ??????
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JAVA ??????
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?????????????

• boolean The value is true or false. ??
• char 16-bit Unicode. ?????
• byte 8-bit signed integer. ????
• short 16-bit signed integer.
• int 32-bit signed integer.
• long 64-bit signed integer.
• float 32-bit signed floating point number. ???
• double 64-bit signed floating point number.

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Wrapper Classes????

• Character
• ?????? char
• Integer, Short, Byte and Long
• ?????? int, short, byte, long
• Float and Double
• ??????? float, double

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Scalar V.S. Object

• 123 ? Literal(???)
• int n 123 ? Scalar(??)
• String s "123" ?????
• Integer n new Integer(123) ?????

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Scalar V.S. Object(?)

• ???????????
• String s "123"
• String z s s // z ??? "123123"
• double d Double.parseDouble(s)
• int i Integer.parseInt(s)
• double x d i // x ??? 123123 246
• ??????? Collection(??)??
• Vector v new Vector()
• v.add(new Integer(123))

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Autoboxing ?????????
public class Boxing public static void
main(String args) Integer i new
Integer(10) System.out.println(i.intValue
() 10)
public class AutoBoxing public static void
main(String args) Integer i 10
System.out.println(i 10)
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?????????

• TypeName variableName INI_VALUE
• double mathScore 75.5
• ClassName variableName INI_VALUE
• String authorName "Bill Day"
• ClassName varName new ClassName() // ????
• Hashtable ht new Hashtable()
• ????
• ClassName ???????????
• variableName ???????????(Camel Naming ?????)
• CONSTANT_NAME ????????

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?????????(Constant Literal)

• final int PASS_SCORE 60
• final long LONG_ONE 14L
• final int HEX_MASK 0x0e
• final int OCT_MASK 016
• final float PI 3.14F
• final double PI 3.14
• final double PI 314e-2
• final String LANGUAGE "Java"

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????

• ????
• gt lt gt lt
• ??????
• !
• ??(???????????)
• ??(???????????)

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????

• ????
• - /
• ???????
• 5 2 ??? 1

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??????????????
15 L ., , (args), (post), (post)-- 14 R
(pre), --(pre), (Positive), -(negative), ,
! 13 R new, (type) 12 L , /, 11 L ,
- 10 L ltlt, gtgt, gtgtgt 9 L lt, lt, gt, gt,
instanceof 8 L , ! 7 L 6 L 5 L
4 L 3 L 2 R ? 1 R , , /,
, , -, ltlt, gtgt, gtgtgt, , ,
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??????????

• int x 5
• x x 1
• x ltlt 2
• boolean hitTop false
• String baseName null
• x
• abs (a gt 0) ? a -a

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????if-then-else
if (a gt b) // A else // B // C
if (a gt b) // A // C
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public class EvenOdd public static void
main(String args) if (args.length !
1) System.err.println("????????")
System.exit(1) int
i Integer.parseInt(args0) String msg
(i 2 0) ? "??" "??"
System.out.println("" i " is an "
msg " number.")
args.length ? args ???? Integer.parseInt()
???????? ???????? ??????? System.err ?
stderr????????
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???????

• ??????(stdin)
• ??? Console(???)
• ???? Input Redirect(??????)????(Keyboard)
• ??????(stdout)
• ??? Console(???)
• ???? Output Redirect(??????)????(tty)
• ??????(stderr)
• ??? Console(???)
• ??? Output Redirect
• ?? http//en.wikipedia.org/wiki/Standard_streams

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????nested if-else, switch-case
switch (a) case 0 // A break
case 1 // B break case 2
// C break default // D
if (a 0) // A else if (a 1)
// B else if (a 2) // C else
// D
if (a 0) // A else if (a 1)
// B else if (a 2)
// C else
// D
Nested ??
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??

• ?????????????
• ?? gt 60 ???
• ?? lt 59 ????
• ?? gt 100 ? lt 0 ??????
• ???????? String args ??
• ????
• java Score 80
• java Score 123
• java Score 59

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????while ? do-while ??
while (A) // B
do // B while (A)
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????for ??
for (A B C) // D
for (int i 0 i lt names.length i)
System.out.println("Hello "namesi)
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??

• ???
• ???????????????
• ????
• java Echo 1 2 3 4??1 2 3 4

• ???
• ?????????
• ????
• java Echo 1 2 3 4??4 3 2 1

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????break ? continue
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??

• ????????????????????
• ???????????
• ?????,???????
• ?????????????
• 0 ???

• ????
• java Even 1 2 3 4??2 4
• java Even 2 3 0 -1 4 5??2 0

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??

• ???? Java ??,??????????????????
• ????
• java Sum 1 2 3 4????? 10??? 2.5

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??

• ???? Java ??,?????? 1 ? 10 ?????,??1234567
  891055
• ???? Java ??,?????? 1 ? n ?????,?? n
  ?????????????????

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Java Applet

• Application Let
• ??????????????

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HelloApplet.java
import java.applet.Applet import
java.awt. public class HelloApplet extends
Applet public void paint(Graphics g)
g.drawString("Hello Applet !!", 50, 50)
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HelloApplet.html
lthtmlgt ltheadgtlttitlegtApplet Demolt/titlegtlt/headgt ltbo
dygt ltapplet codebase"classes" code"HelloApplet.c
lass" width"350" height"200"gt This browser does
not appear to support Applets. lt/appletgt lt/bodygt lt
/htmlgt
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Applet ???
ltHTMLgtltHEADgtltTITLEgtApplet ???lt/TITLEgtlt/HEADgt ltBODY
gt ltAPPLET CODE"HelloApplet2" HEIGHT"200"
WIDTH"200"gt ltPARAM NAME"name"
VALUE"???"gtlt/APPLETgt lt/BODYgt lt/HTMLgt
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HelloApplet2.java
import javax.swing. import java.awt. public
class HelloApplet2 extends JApplet private
String name null public void paint(Graphics
g) g.drawString(name " ??!", 100, 100)
public void init() this.name
this.getParameter("name")
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??UIJavax.swing.JOptionPane

• showConfirmDialog
• ????, yes/no/cancel.
• showInputDialog
• ????
• showMessageDialog
• ????
• showOptionDialog
• The Grand Unification of the above three.

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JOptionPane
import javax.swing. public class Square
public Square() String s
JOptionPane.showInputDialog("???????") int n
Integer.parseInt(s) int nn n n
JOptionPane.showMessageDialog(null, s "
???? " nn, "?????",
JOptionPane.PLAIN_MESSAGE) public static
void main(String args) Square square new
Square()
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class ConfirmExit implements Application.ExitListe
ner public boolean canExit(EventObject e)
if (dctsdk.isServerOnLine()) int option
JOptionPane.showConfirmDialog(
getFrame(), "Do you really wants
exit?", "Confirmation Required",
JOptionPane.YES_NO_OPTION) if (option
JOptionPane.YES_OPTION)
dctsdk.stopServer() else
return false return true
public void willExit(EventObject e) //
ask for confirmation on exit getApplication().addE
xitListener(new ConfirmExit())
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Object possibleValues IDctSdk.KeyboardCase
Options.ToUpper " ????", IDctSdk.KeyboardCaseO
ptions.ToLower " ????", IDctSdk.KeyboardCaseOp
tions.Intact " ???", IDctSdk.KeyboardCaseOptio
ns.Inverse " ?????" String selectedValue
(String) JOptionPane.showInputDialog(this.getFrame
(), "????????????????", "????????",
JOptionPane.INFORMATION_MESSAGE, null,
possibleValues, possibleValues0) String ss
selectedValue.split(" ") if (ss0.equals(IDctSdk
.KeyboardCaseOptions.ToUpper.toString()))
dctsdk.setKeyboardCase(IDctSdk.KeyboardCaseOptions
.ToUpper.ordinal()) else if (ss0.equals(IDctS
dk.KeyboardCaseOptions.ToLower.toString()))
dctsdk.setKeyboardCase(IDctSdk.KeyboardCaseOptions
.ToLower.ordinal()) else if (ss0.equals(IDctS
dk.KeyboardCaseOptions.Inverse.toString()))
dctsdk.setKeyboardCase(IDctSdk.KeyboardCaseOptions
.Inverse.ordinal()) else
dctsdk.setKeyboardCase(IDctSdk.KeyboardCaseOptions
.Intact.ordinal()) setStatusMessageKeyboardCase
(dctsdk.getKeyboardCase())
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? BufferedReader ? Console ??????
BufferedReader con new BufferedReader( new
InputStreamReader(System.in))
String s con.readLine() int n -1 try
n Integer.parseInt(s) catch
(NumberFormatException ex) ex.
printStackTrace()
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? Scanner? Console ????

• java.util.Scanner

Scanner sc new Scanner(System.in) int i
sc.nextInt()
Scanner sc new Scanner(new File("myNumbers")) w
hile (sc.hasNextLong()) long aLong
sc.nextLong()
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??

• ???? Java ??,?????? 1 ? n ?????,??
  n101234567891055
• ??/????
• ? JOptionPane ?? n ?,JOptionPane ??
• ??
• ? Integer.parseInt() ???????

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??

• ?????,??????????,???????????????????
• ??
• Integer.toBinaryString(number) ???
• Integer.toOctalString(number) ???
• Integer.toHexString(number) ????

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??

• ???????
• ???????
• ????? \t ??