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. Java Programming i

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1.6.1 Java Virtual Machine....................................................................................................................................111.6.2 Java Runtime Environment...........................................................................................................................121.6.3 Java Development Kit...................................................................................................................................13

1.7 JL............................................................................................................................................. 151.8 #;...........................................................................................................................16

1.8.1 Java Platform, Standard Edition...................................................................................................................181.8.2 Java Platform, Enterprise Edition.................................................................................................................181.8.3 Java Platform, Micro Edition........................................................................................................................19

1.9 ............................................................................................................................................... 201.9.1 UJ#..................................................................................................................201.9.2 U5................................................................................................................22

1.10 VL Java API...................................................................................................................................................... 24JY....................................................................................................................................................... 25

2 .................................................................................................................................272.1 ;5#..........................................................................................................272.2 #)Z........................................................................................................................................... 29

2.2.1 5# ...................................................................................................................................................... 292.2.2 Identifier........................................................................................................................................................ 302.2.3 ;##........................................................................................................................................................... 31

ii Java Programming .

2.2.4 ))#Z........................................................................................................................................... 322.2.5 LL ......................................................................................................................................................... 332.2.6 UVL;\.................................................................................................................................................. 33

2.3 UVY......................................................................................................................................... 332.3.1 UV.......................................................................................................................................... 352.3.2 UV)).....................................................................................................................................352.3.3 UV)Z5 ........................................................................................................................362.3.4 UV)..............................................................................................................................37

2.4 )L;\................................................................................................................................................. 382.4.1 Z)\ZL .............................................................................................................................................392.4.2 L;\............................................................................................................................................................ 412.4.3 )L;\....................................................................................................................42

2.5 )Z ......................................................................................................................................................... 452.5.1 )Z#.......................................................................................................................462.5.2 )Z))#............................................................................................................................482.5.3 )Z#......................................................................................................................502.5.4 )Z....................................................................................................................................522.5.5 Z)Z))Z..............................................................................................................53

2.6 UV.............................................................................................................................................. 542.6.1 UVZ)\ZL...............................................................................................................552.6.2 Typecasting................................................................................................................................................... 57

2.7 UVU........................................................................................................................................... 582.7.1 String................................................................................................................................................... 602.7.2 Math................................................................................................................................................... 62

2.8 Z)\J#J........................................................................................................................................ 642.8.1 System.out.println()...................................................................................................................................... 642.8.2 )UVU Command Line.......................................................................................................65

JY....................................................................................................................................................... 66 3 %................................................................................................................................................. 69

. Java Programming iii

3.1 Z)\UJ......................................................................................................................................... 693.2 UZ..........................................................................................................................................70

3.2.1 Z)\ if........................................................................................................................................................... 703.2.2 Z)\ if..else.................................................................................................................................................. 723.2.3 Z)\ if U..........................................................................................................................................743.2.4 Z)\ switch.................................................................................................................................................. 78

3.3 UZYZ .............................................................................................................................................803.3.1 Z)\ while.................................................................................................................................................... 813.3.2 Z)\ do..while.............................................................................................................................................. 833.3.3 Z)\ for........................................................................................................................................................ 84

3.4 UU (Nested Structure)................................................................................................................863.4.1 Z)\ break, continue label ...............................................................................................................88

JY....................................................................................................................................................... 90

4 ,-.............................................................................................................................................934.1 #5#.............................................................................................................93

4.1.1 5#....................................................................................................................................................... 934.1.2 .............................................................................................................................................................. 944.1.3 J) ................................................................................................................................................... 954.1.4 ........................................................................................................................................................... 97

4.2 ;5#U...............................................................................................984.2.1 ..........................................................................................................................................984.2.2 J)................................................................................................................................994.2.3 ........................................................................................................................................ 994.2.4 U5#..................................................................................................................1014.2.5 ;U5#................................................................................................................102

4.3 J)L5#........................................................................................................1044.3.1 LJU ................................................................................................................................................... 1044.3.2 ................................................................................................................................................ 106

iv Java Programming .

4.3.3 ;UV..................................................................................................................................1074.4 ;5#\U abstract #................................................109

4.4.1 abstract......................................................................................................................................1094.4.2 #................................................................................................................................................. 111

4.5 5................................................................................................................................................................ 1134.5.1 U5........................................................................................................................114

4.6Unified Modeling Language................................................................................................................................1154.6.1 .................................................................................................................................1164.6.2 5#............................................................................................................................116

4.7 )Y)...............................................................................................................................117JY..................................................................................................................................................... 119

5 003............................................................................................................1215.1 Java Foundation Class ........................................................................................................................................ 121

5.1.1 5 AWT............................................................................................................................................. 1225.1.2 5 Swing............................................................................................................................................ 124

5.2 Container ....................................................................................................................................1255.2.1 Frame................................................................................................................................................ 1255.2.2 Panel.................................................................................................................................................. 1275.2.3 Dialog................................................................................................................................................ 1285.2.4 JFrame............................................................................................................................................... 128

5.3 ))Lm...............................................................................................................1315.3.1 BorderLayout.............................................................................................................................................. 1325.3.2 FlowLayout................................................................................................................................................. 1355.3.3 GridLayout.................................................................................................................................................. 137

5.4 Lm5 Swing..............................................................................................................1385.4.1 JButton............................................................................................................................................. 1405.4.2 JLabel............................................................................................................................................... 1415.4.3 JTextField........................................................................................................................................ 144

. Java Programming v

5.4.4 JTextArea.........................................................................................................................................1455.4.5 JcheckBox JRadioButton........................................................................................................1475.4.6 JComboBox..................................................................................................................................... 1505.4.7 JList.................................................................................................................................................. 151

5.5 UV........................................................................................................................................................ 1535.5.1 U JMenuBar...................................................................................................................................1545.5.2 U JMenu......................................................................................................................................... 1545.5.3 U JMenuItem..................................................................................................................................1555.5.4 JCheckBoxMenuItem......................................................................................................................1575.5.5 UVL......................................................................................................................................... 159

5.6 J) Component......................................................................................................................161JY..................................................................................................................................................... 163

6 ,-.........................................................................................................1656.1 ................................................................................................................................................................. 165

6.1.1 ;U........................................................................................................................................1656.1.2 LL argument ..................................................................................................................................1666.1.3 )L;\L)..................................................................................................................................1726.1.4 modifier .................................................................................................................................... 172

6.2 ;U)LJU.............................................................................................1736.2.1 Accessor..................................................................................................................................1756.2.2 ;## this.................................................................................................................................................. 178

6.3 ;U)...........................................................................................1796.3.1 ;\VU...................................................................................................................................1826.3.2 ;## protected ...................................................................................................................................... 1836.3.3 ;\\ Object........................................................................................................................................ 1846.3.4 ;## super .............................................................................................................................................. 185

6.4 ;UV.......................................................................................................................................... 1866.4.1 Dynamic Binding........................................................................................................................................ 186

vi Java Programming .

6.4.2 ZU;;;\L).......................................................................................................1876.4.3 Virtual Method Invocation..........................................................................................................................1906.4.4 LL argument UV.............................................................................................................1906.4.5 )Z instanceof.............................................................................................................................1916.4.6 Casting 5#................................................................................................................................192

6.5 Constructor.......................................................................................................................................................... 1946.5.1 ; Constructor..................................................................................................................................1956.5.2 )YZZ)\ new ..............................................................................................................1966.5.3 Constructor Overloaded.....................................................................................................................1976.5.4 this()............................................................................................................................................... 1986.5.5 super().............................................................................................................................................. 1996.5.6 )YZ Constructor............................................................................................................200

6.6 ;\\ Object...............................................................................................................................2026.6.1 toString()......................................................................................................................................... 2026.6.2 equals()............................................................................................................................................ 203

6.7 Wrapper....................................................................................................................................... 2046.7.1 Autoboxing.................................................................................................................................................. 205

6.8 ;##\ ;\Z)........................................................................................................................................... 2066.8.1 J) static.................................................................................................................................2066.8.2 static.........................................................................................................................................2076.8.3 Static Initializer........................................................................................................................................... 2086.8.4 ;## final................................................................................................................................................ 209

6.9 ......................................................................................................................................................... 2106.9.1 ;\VL.....................................................................................................................2106.9.2 ;\VL...................................................................................................................212

6.10 Generic Types.................................................................................................................................................... 2136.10.1 Generic..................................................................................................................................214

6.11Annotation.......................................................................................................................................................... 2156.11.1 Annotation Document...............................................................................................................................216

. Java Programming vii

6.11.2 Annotation ;\U#..............................................................................................................217JY..................................................................................................................................................... 218

7 %.3...........................................................................................................................2217.1 J#............................................................................................................................................................. 2217.2 AWTEvent........................................................................................................................................................... 2237.2.1 ActionEvent...................................................................................................................................................... 2247.2.2 WindowEvent................................................................................................................................................... 2257.2.3 MouseEvent...................................................................................................................................................... 2257.2.4 ItemEvent.......................................................................................................................................................... 2267.2.5 Event \ ....................................................................................................................................................... 2277.3 # Listener..............................................................................................................................2277.4 ))J#.......................................................................................................................................2307.4.1 U5#..............................................................................................................2317.5 U5#....................................................................................................................2327.5.1 U5#;)..........................................................................................................2347.5.2 )wJ#J#.................................................................................................................2357.5.3 Event Adapter..........................................................................................................................2377.5.4 U anonymous .....................................................................................................................238JY..................................................................................................................................................... 239

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8.2.1 \)#UVY.................................................................................2428.2.2 U)#UVY...........................................................................................2438.2.3 ;U#......................................................................................................................2458.2.4 ZL\UU)# ...........................................................................................2468.2.5 UZ)\ for \U#.............................................................................................247

viii Java Programming .

8.2.6 U ArrayIndexOutOfBoundsException .......................................................................2488.3 #UV..................................................................................................................................249

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. Java Programming ix

10.1 Stream ............................................................................................................................................................... 28910.1.1 5 java.io..........................................................................................................................................29010.1.2 Byte Stream.......................................................................................................................29210.1.3 InputStream.....................................................................................................................................29210.1.4 OutputStream..................................................................................................................................29410.1.5 Character Stream...............................................................................................................295

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x Java Programming .

. Java Programming xi

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public class HelloWorld {public static void main(String args[]){ System.out.println("Hello World");}

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22 VUYU .

import java.awt.*;import javax.swing.*;public class HelloWorldApplet extends JApplet {

public void paint(Graphics g) {g.drawString("Hello World",20,20);

}}

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HelloWorld Example

1.13 * 1.3 -

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28 Y .

public class Main {public static void main(String args[]) { Student s1 = new Student(); s1.sayHi(); }

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. Y 29

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30 Y .

/* This program is to show how to write comments */public class CommentDemo {

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. Y 31

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. Y 33

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. Y 35

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. Y 37

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38 Y .

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. Y 39

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40 Y .

public class VariableAssignDemo {public void showDemo() {

int x,y; boolean b1; float z = 3.414f; /* The program will not be

compiled successfully if a character f is missing */

double w; x = 5; y = 4; b1 = (x > y); w = x * 3.2; System.out.println("x = " + x + " y = " + y); System.out.println("b1 = " + b1);

System.out.println("z = " + z + " w = " + w); }}-----------------------------------------------------------------public class Main {

public static void main(String args[]) { VariableAssignDemo obj = new VariableAssignDemo(); obj.showDemo(); }

}

2.3 * 2.3

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. Y 41

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42 Y .

public class ConstantDemo {public void showDemo() {

final int MAXIMUM = 10;final double MIN_GPA;System.out.println("Maximum is " + MAXIMUM);MIN_GPA = 2.00;System.out.println("Minimum GPA is " + MIN_GPA);

// MIN_GPA = 3.00; //illegal}

}--------------------------------------------------------public class Main {

public static void main(String args[]) { ConstantDemo obj = new ConstantDemo(); obj.showDemo(); }

}

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. Y 43

public class VariableScopeDemo {public int i; // object variablepublic void method1() {

int j = 4; // local variableint k = 2; // another local variable

}public void method2() {

int j = 0; // local variableSystem.out.println(i); // calling an object variable i

// System.out.println(k); // illegal}

}

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44 Y .

public class ScopeExample {private int i=1;public void method1() {

int i=4, j=5;this.i = i+j;method2(7);

}public void method2(int i) {

int j=8;this.i = i+j;

}}----------------------------------------------------------public class TestScoping {

public static void main(String args[]) {ScopeExample scope = new ScopeExample();scope.method1();

}}

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public void demoMethod(){int x = (int)(Math.random()*10);int y,z;if (x > 5) { y = 6;}z = x+y;

}

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. Y 45

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46 Y .

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. Y 47

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48 Y .

public class IncrementDemo {public void showDemo() {

int x;int y;x = 5;y = x++;System.out.println("x = "+x+" y = "+y);y = ++x;System.out.println("x = "+x+" y = "+y);

}}------------------------------------------------------public class Main {

public static void main(String args[]) { IncrementDemo obj = new IncrementDemo(); obj.showDemo(); }

}

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50 Y .

public class BooleanDemo { public void showDemo() {

int x = 5; int y = 4; boolean b1;

b1 = (x != y); System.out.println("x not equal y is " + b1);

System.out.println("y less than 0 is " + (y < 0)); }}----------------------------------------------------------------public class Main {

public static void main(String args[]) { BooleanDemo obj = new BooleanDemo(); obj.showDemo(); }

}

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. Y 51

)Z;\;\ && || ;L )Z# short circuit ;\ && y AND L x\L & ;\ && J;;U#)y5 L;) || ;\y OR L x\L | ;\ || J;;U#)y )LL

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Ly 0111 L\ >>, >>> > 32);

x\) x 0 LL 32

\ >> y\\ x\UUyL 1 5LL 1 LUyL 0 5LL 0 L\ >>> >) Z5UL 2 Z)Z;\\ L\U ( 1 128/21 = 64-128 >> 4 -128/24 = -8128 ) (R to L) ++, --, +, -, ~, ! (data type)2 >)) (L to R) *, /, %3 >)) (L to R) +, -4 >)) (L to R) , >>>5 >)) (L to R) , =, instanceof6 >)) (L to R) ==, !=7 >)) (L to R) &8 >)) (L to R) ^

. Y 53

9 >)) (L to R) |10 >)) (L to R) &&11 >)) (L to R) ||12 )>) (R to L) ?:

13 )>) (R to L) =, +=, -=, *=, /=, %=, =, >>>=, &=, ^=, |=

)LL Z)\x = 2+3*4-(7+2);

Z)#Z));Y1. Z)#L 7+2 ZUU

x = 2+3*4-92. Z)#L 3*4 ZUU

x = 2+12-93. Z)#L 2+12 ZUU

x = 14-94. Z)#L 14-5 ZUU

x = 5

2.6 ,

##;)VZ# ;\;UVyL UZU)##y);Y

;;\)VZ)Y);UVy double ) ZUU)#;\;UVy double

;;\)VZ)Y);UVy float ) ZUU)#;\;UVy float

;;\)VZ)Y;UV;\L) ;)UV (type conversion) );Yo U)VZ)x\;UVy double )VZ;)x\VU;

UVy double ))o U)VZ)YLU;UVy double L;)VZ)x\;\;UV

54 Y .

y float )VZ;)x\VU;UVy float ))o U)VZ)YLU;UVy double float L;)VZ)x\

;\;UVy long )VZ;)x\VU;UVy long ))

o ;\ )VZ)YU;UVy int

)UU5UL)#;\UZ## ;UVy int yLU ))YZ)\L;Y

byte b1, b2, b3;b1 = 2;b2 = 4;b3 = b1+b2; // illegal

xyZ)\;\LVU \ b1+b2 UL)#;\;UVy int x\LZLU));\;UVy byte U

2.6.1 DD0ZUZ)\ZLU;UV)UUUV#

UU) Lint i = 4;double x = 3.0;

;;\)#;UV;\L) #ZUV)YUU) UV;V

1. UV;\UxY (widening conversion) UV;\;5LyUV;\;LL

2. UV;\ (narrowing conversion) UV;\;LLyUV;\;5 x\;U;;UVL

ZUVL ;\UVUUxYU )V;\ 2.8 x\;));Y

UV)Z5UyUV)U UV float UyUV double U UV)Z5;;)U);Y

. Y 55

byte short int long

UV char UyUV int U UV boolean L;))#)UVY\

2.8 *

Z)\ZL U)##yUV;\;5LUV) ZUVUyUV))L))L Z)\

int i = 4;long l = i;

# i V)UV int Uy long ))

Z)\double x = 3;

#;\;Ly 3 V)UV int Uy double ))

;;\Z)\ZL;UV);\;5L UV# LUV#Uy;\5L)UV))) L#UU)Y# (compile error) )LL Z)\

int amount = 123L;

float f = 4.0;L#LU \UV#;LLUV)

;\ 2.9 )LUUV x\ZU;YL# LU

56 Y .

( 2.9 %%1

2.6.2 TypecastingZUV UyUV;\;5U U;;\;L

typecasting x\;V);Y(targetType) expression

;\ targetType UV;\U

U typecasting LZU;\;Z)\x\ZyUUVU;5#LU LZUUVLV;

)LL Z)\int amount = (int)3.0;

Z# 3.0 ;\;UVy double Uy 3 ;\;UVy int

)LZ)\int x;double y = 1.25;x = (int)y;

Z# y ;\;L 1.25 U;UVy int ;\;L 1 LZU);\yL

. Y 57

public class PromotionDemo {public void showDemo() {

int i;long l;float fl = 4.2f;i = 4;l = i;fl = i;double x = fl;fl = 4.2; //illegal

}}

;\2.10 )LU typecasting UV # b1+b2 U)#;\;UVy int xUUVUy byte \;\ZLU)) b3 x\;UVy byte U L;))L 3.2 x\;UVy double VUVUy float

( 2.10 typecasting 1

2.7 ,,

)L;\;\yUV\ x\LLUVY yUV Ux\55# Ly

1. UV;\y2. UV;\y#)LUV;\y UV String String LLUVY L

y;\U Java API L Z)\String id;

yZ)\) id Uy5# String Z))LUV;\y#VLx;\ 8

58 Y .

public class TypecastingDemo {public void showDemo() {

byte b1 = 4;byte b2 = 3;byte b3;b3 = (byte) (b1 + b2);float f1;f1 = (float) 3.2;

}}----------------------------------------------------------------public class Main {

public static void main(String args[]) { TypecastingDemo obj = new TypecastingDemo(); obj.showDemo(); }

}

UVU;;5UVLZ;\L 5UVUVY )Y;YUV;\5LZUVUyZLU;\5UVLZ L;UVY UV;\5LZyLUV L Z)\

int x = 7;String s = new String(Thana);

y);\;UVY int ;\\ x U5Ly 7 y)UVU (x\55#) s String U5LyUL Thana x\))Y);5UVLZ)V;\ 2.9 x\L;\5) x yLUV;\yL 7 LL) s yZLULZ;\U5UL Thana

2.9 %-*%

) (5#) UVUy;\) ( 5#) LL;Y;\LZ\5UV ;;\))LyJ) 5# J) ZZLU\UU;Ly null )) x\Y;\LZ\5UVL )UVUVUxY \;;UZ)\ new L Z)\

Date d;

yZ)\) (5#) d Uy Date ;\ZU Java API ULLZ)V;\ 2.10 ()

Z)\d = new Date(16, 8, 2002);

yZ)\Y;\LZ\5J)5#;\\ d ;\;VL 3 ) day, month year x\;UVy int )V;\ 2.10 ()

. Y 59

()

() 2.10 %-*%

2.7.1 String String y;\ZU Java API );\;UVy String 55#x\

x\ String ;UL5#)\ );Y String y5#;\;L;\UVx\5U ;\VL\ double quote

( ) )LL This is a java course

String y5#;\VUxYZLULZyUUZ)\ new )LL UZ)\

String s = Thana;

LZy;\UUZ)\String s = new String(Thana);

;;\LUZ)\ new ZZLULZU;\J\ ( ) String Pool L;UVLL ;5UZLU;\YZ) LU)L;5UUxYLZZLUU)Y L;;\UZ)\ new UULY;\LZ ;\ 2.11

60 Y .

)LUZL5# String )Y;;\ULUZ)\ new 5# s1 s2 ;UVLZyZLU;\;) L s3 ;UVLZyZLU;\L)\;UUxYL)V;\ 2.11

( 2.11 )9 String

2.11 %-* String %

String y5#;\;\LLU (Immutable Object) ZLU)5# String L y;\ZLULZ5#)L LLU;;\LZLU )LL Z)\

String s1;s1 = Thanachart;s1 = Somchai;

;ZUZLULZ5# s1 ;\ )V;\ 2.12 x\y

. Y 61

public class StringDemo {public void showDemo() {

String s1 = "Thana";String s2 = "Thana";String s3 = new String("Thana");

}}-------------------------------------------------------------public class Main {

public static void main(String args[]) { StringDemo obj = new StringDemo(); obj.showDemo(); }

}

)L;\ZLU5UV String LZ

2.12 %%*-*

String y5#;\;)Z;\U\UUUU) U\ + L

String s1 = Hello+ World;

)Z\UU\UV String ))VZ;\yUV\ ;\LL String U x\UV)LUy String ))L Z)\

String s1 = This;String s2 = s1+ is a test ;String s3 = s1+4;

ZUUU) s2 y This is a test s3 y This4)Z\\U;)ZL;\U\ += \\U UZL5# String U\L Z)\

String s1 = This;s1 += is a test;

yZ)\\U5# s1 )U;\L is a test U55# s1 L ZU s1 ;Uy This is a test

2.7.2 MathJava API UZU; Math ;\VL5 java.lang x\;L ))

w#)Z)\#L Math y final J y (;;## static VL x\Lx;\ 6) ;UL;YZULZyUU 5# L;L\UL Math.exp(4.0); yZL exponential

62 Y .

4.0 Math UL;\));Y

- final static double E = 2.7182818284590452354;- final static double PI = 3.14158265358979323846;

x\;U Math.E ;Ly 2.718281828 Math.PI ;Ly 3.141582653

\ Math ;\Z););Y- static int abs(int x);- static long abs(long x);- static float abs(float x);- static double abs(double x);- static double acos(double x);- static double asin(double x);- static double atan(double x);- static double atan2(double x, double y);- static double ceil(double x);- static double cos(double x);- static double exp(double x);- static double floor(double x);- static double log(double x);- static int max(int x, int y);- static long max(long x, long y);- static float max(float x, float y);- static double max(double x, double y);- static int min(int x, int y);- static long min(long x, long y);- static float min(float x, float y);- static double min(double x, double y);- static double pow(double x, double y);- static double random();- static double rint(double x);- static int round(float x);- static long round(double x);- static double sin(double x);- static double sqrt(double x);- static double tan(double x);

. Y 63

2.8 D,%.%

#)\ U;LUVU\U ;Z)#;\U LUVU)#;L J/#J (Input/Output) ;;;))J/#J ;;\;\U)J/#J L;L ;x\UJ (Standard Input) U #J (standard output) ;5#;\yJ/#J5# System.in, System.out System.err

5# System.in y5#;\;Z)LUVJ#J x\)\5;##

5# System.out y5#;\;Z)UVJ##J x\)\

5# System.err y5#;\;Z)U (Error) J#;\UU x\)\Zy

2.8.1 System.out.println()5# System.out x5#;\\ out x\yJ) System 5#;\

\ out y5# PrintStream ;\;;\;\U)VL L;\ U)\

print(String s) println(String s)x\)YUUV;\; argument yUV String

println() ;UxY)L)#UV;\U print() println() ) argument ;\yUV\ x\yUV String U)))LL Z)\

int x = 3;System.out.println(x);

yJZ)\#L) x ;\;UVy int UV int Uy String Ux#U ;\ 2.12 )LUZ)\

64 Y .

System.out.print() System.out.println() \UVL )V;\ 2.13

( 2.12 ()

2.13 * 2.12

2.8.2 Command Line main() ;\yZL\UZJ# ; argument y String

args[] x\x)# (Lx;\ 8) args ;\;UVy String x\) argument ;\LL command line U;)LZ)V;\ 2.14 x\yZU args[0];Ly Tommy ) args[1] ;Ly boy ;\ 2.13 y)LJ command line U

. Y 65

public class PrintDemo {public void showDemo() {

int x = 3, y = 4, z = 5;System.out.print("x = "+x);System.out.println(" y = "+y);System.out.println("z = "+z);

}}---------------------------------------------------------------public class Main {

public static void main(String args[]) { PrintDemo obj = new PrintDemo(); obj.showDemo(); }

}

( 2.13 @ command line

2.14 * 2.12

%

y5# ;\;Z;\Z)Z5# ;#;5# 5#;\VU UJ) V;UU\;U5#;UZ)\ new U;U 5# U;\VL x\#LU;YUyLx\

identifier \;\)YxY x\y\ \) \ \

L;\ x\Uy)Y\ )Y\

Z) xYUU))#L Z)) xYUU))#5 U\;\)YxY;L 1 Z xYUZLU))#L UL);##

;## \;\; #UZ)\;\UZZ);##L)

66 Y .

public class InputDemo {public static void main(String args[]) {

System.out.println("My name is "+ args[0] +" and I am a " + args[1]);

}}

UVL;\ Z;\UUV;\y) )) U L UVLy UVY UVU UVY;\U;)Y 8 char, byte, short, int, long,

float, double boolean UV;\5VLLy )L;\ x\)UV;\

;\LUUZ)\ZL LL;\UV;\ZLU;)Y;L;\LU

);\;UVU;\Z;\LUUZ)\ZL L;\ZUL;## final UZ)\\ L;\);\VL5 ;UVL5L)Y )Z;\U;)Y 4

)Z# : +, -, *, /, %, +=, -=, *=, /=, %=, ++ -- )Z# : !, &&, &, || | )Z))# : =, == != )Z : ~, &, |, ^, >>, >>>,

68 Y .

3 %

Y;YyZZ)\;\;\U)UJ x\yJZ)ZZ)\L LxZ)\UJ Z)\UZx\ULZ)\ if,if..else switch Z)\UZYZx\ULZ)\ while, do..while for U;YLxZ)\UJU

3.1 D%

Z)\UJ (Control Structure) yZ)\;\UZZ)ZZ)\L ;UJV

1. UZ) (Sequential Structure)2. UZ (Selection Structure)3. UZYZ (Repetition Structure)

)\Z)\;UJZ) ZZ)Z)\;\;VL x\\Z main()ZZ)\ main()Z;Z)Z)\L\ ;;\;;U5# UZZ)\)Y \YJZ)\JU5)ZZ)\;\;U )V;\ 3.1

3.1 %

. UJ 69

public class Sample {public static void main(String args[]) {

Student s = new Student();String name;name = s.getName();System.out.println(name);

}} public class Student {

String name;public String getName();

return name;}

}

3.2 D

UZyUZJZ)\;;\##;Ly\ x\JZ)\UZUZ)\)L;Y

Z)\ if Z)\ if..else Z)\ if U (nested if) Z)\ switch

3.2.1 D ifZ)\ if ;V);Y

if (logical expression) {statements

}

;\ logical expression ##;\U)#yUVL;\ boolean statements JZ)\

JZ)\;\VL5 { } Z;;\##ULy x\Z)\ if Z)Zy## (flowchart) U)V;\ 3.2

3.2 if

70 UJ .

)LUZ)\ if ;);Yif (radius >= 0) {

area = radius*radius*Math.PI;System.out.println(area);

}

)L;YJZ)\;\VL5 (Z)\ZL) area Z)\) Z;;\# radius >=0 y L) radius ;LLL) 0

;;\JZ)\5 { } ;;Z)\;;\)\ { } UL Z)\if((x > 0) && (x < 10)) { System.out.println(x);}

;LUyif((x > 0) && (x < 10))

System.out.println(x);

LL5;;\;U5 { } \UUL LL\Z)\ (LU;Lx\Z)\UU5 { } )

( 3.1 )() if

. UJ 71

import javax.swing.JOptionPane;public class SampleIf { public void showDemo() { String inputStr = JOptionPane.showInputDialog("Enter value"); int score = Integer.parseInt(inputStr); if (score >= 50) { JOptionPane.showMessageDialog(null, "You pass");

// null to tell that there is no parent frame } }}------------------------------------------------------------------------public class Main { public static void main(String[] args) { SampleIf obj = new SampleIf(); obj.showDemo(); }}

;\ 3.1 y)L;\UZ)\ if ))U5 x\yUV String ;\5VL);\\ inputStr ;U;\\ showInputDialog JOptionPane UxLLy argument Integer.parseInt() \ZUV String UyUV int UZU) score x\Z)\ if LU) score ;LLL) 50 #U You pass 5;\;U showMessageDialog JOptionPane )L)#;\U);\ 3.1 )V;\ 3.3

3.3 * 3.1

JOptionPane

JOptionPane %( DialogBox %%% %() - showConfirmDialog 9)( yes/no/cancel - showInputDialog 9())1 String - showMessageDialog 9

3.2.2 D if..elseZ)\ if L;ZZ)\ U##;Ly5 ))YUUZZ)\Z)\\

##;Ly5 UUZ)\ if..else x\;VZ)\);Yif (logical expression) {

true statements} else {

false statements}

72 UJ .

;\ true statements JZ)\Z)L false statements JZ)\Z)L5

;##ZZ)\;Y)V;\ 3.4

3.4 if..else

)LUZ)\ if..else ;);Yif (radius >= 0) {

area = radius*radius*Math.PI;System.out.println(area);

} else {System.out.println(Negative radius);

}

)L;YU) radius ;LLL) 0 (#;Ly) ZZL ZL#L) area LU) radius ;LUL 0 (#y5) U Negative radius

. UJ 73

( 3.2 )() if..else

;\ 3.2 y)LUZ)\ if..else #U You pass UL) score ;\)U5 ;LLL) 50 #U You fail UL score ;LUL 50 ;)L)#)V;\ 3.5

3.5 * 3.2

3.2.3 D if Z)\ if if..else ;\UVLUZ)\ if if..else \UL ##;\

V;\ 3.6 x\;)YZ ZJZ)\;\ 3 U##;\ 1 y5 LUy)###;\ 2 x\U;Ly ZJZ)\;\ 1 LU;Ly5ZJ Z)\;\ 2

74 UJ .

import javax.swing.JOptionPane;public class SampleIfElse { public void showDemo() { String inputStr = JOptionPane.showInputDialog("Enter value"); int score = Integer.parseInt(inputStr); if (score >= 50) { JOptionPane.showMessageDialog(null, "You pass"); } else { JOptionPane.showMessageDialog(null, "You fail"); } }}

3.6 if *

##V;\ 3.6 ;\;yZ)\ if UU);Yif (logical expression 1) {

if (logical expression 2) {statements 1

} else {statements 2

}} else {

statements 3}

)LLif (radius >= 0) {

area = radius*radius*Math.PI; if(area >= 500.0) {

System.out.println(Big Circle); } else { System.out.println(Small Circle); }

} else { System.out.println(Negative radius);

}

. UJ 75

3.7 if *

UZU);;;\y)##V;\ 3.7 x\;)YZ ZJZ)\;\ 1 U##;\ 1 y LUy5)###;\ 2 x\U;Ly ZJZ)\;\ 2 LU;Ly5ZJZ)\;\ 3 x\;VZ)\);Y

if (logical expression 1) {statements 1

} else {if (logical expression 2) { statements 2} else { statements 3}

}

;;Y;\;Z)\ if UUL V if..else if..else ;V Z)\);Y

76 UJ .

if (logical expression 1) {statements 1

} else if (logical expression 2) {statements 2

} else {statements 3

}

)LUZ)\ if..else if..else ;);Yif (score >= 80) { System.out.println(A);} else if(score >= 70) { System.out.println(B);} else if(score >= 60) { System.out.println(C);} else if(score >= 50) { System.out.println(D);} else { System.out.println(F);}

)L;Y#)) A U) score ;LLL) 80 #)) B U) score ;L)YL 70 x 79 #)) C U) score ;L)YL 60 x 69 #)) D U) score ;L)YL 50 x 59 #)) F U) score ;L\ZL 50

3.3 UZ)\ if..else if..else

;\ 3.3 )LUZ)\ if..else if..else ;YLL;\U55 #UL Value is one UL;\Uy 1 #UL

. UJ 77

import javax.swing.JOptionPane;public class SampleIfElseIf { public void showDemo() { String inputStr = JOptionPane.showInputDialog("Enter value"); int x = Integer.parseInt(inputStr); if (x == 1) { JOptionPane.showMessageDialog(null, "Value is one"); } else if (x == 2) { JOptionPane.showMessageDialog(null, "Value is two"); } else { JOptionPane.showMessageDialog(null, "Other than 1 and 2 "); } }}

Value is two UL;\Uy 2 #UL Other than 1 or 2 UL;\UyL\

3.2.4 D switchZ)\ switch yZ)\UZ ;V);Y

switch (expression) {case value 1 : statements 1

break;case value 2 : statements 2

break; :

case value N : statements N break;

default : statements N+1 break;

}

;\ expression #;\U;UVy char, byte, short int L)Y value 1 .. value N UVL;\x\;UV;\U)UV expression

Z)\ switch L#;\yUV char, byte, short int ;;\L#;L)L;\ 1 ZJZ)\;\ 1 U;L)L;\ 2 5ZJZ)\;\ 2 U;L)L;\ N 5ZJZ)\;\ N L;;\;LL)L Z)\ case 5ZJZ)\ default JZ)\;\ N+1 x\)YZU)##V;\ 3.8

78 UJ .

3.8 switch

)LUZ)\ switch ;);Yswitch (x) {

case 1 : System.out.println(One); break; case 2 : System.out.println(Two); break; case 3 : System.out.println(Three); break;default : System.out.println(Other);

}

)L;Y#UL x )YL 1 x 3 #UL other UL x yL\ Z)\ switch ;UZL );Y

#U;UVy char,byte,short int L)Y UV#L;\ 1 x N UyUV;) Z)\ break JZ5 { } UL;Z)\ break ZZ)\) )L

. UJ 79

Lswitch (x) {

case 1 : System.out.println(One); case 2 : System.out.println(Two); break; default : System.out.println(Other);

}

#U One U Two ;;\ x ;Ly 1 \ default ;L;5U

;\ 3.4 )LUZ)\ switch x\U)#yUL Value is one U);\U;Ly 1 yUL Value is two U);\U;Ly 2 yUL Other than 1 or 2 U);\U;L\

( 3.4 )() switch

3.3 DD UZYZ yZ)\;\U)\UJZ)\ ZYZ)Y\;\J x\JZ)\

UZYZUZ)\ Z)\ while Z)\ do..while Z)\ for

80 UJ .

import javax.swing.JOptionPane;public class SampleSwitch { public void showDemo() { String inputStr = JOptionPane.showInputDialog("Enter value"); int x = Integer.parseInt(inputStr); switch (x) { case 1: JOptionPane.showMessageDialog(null, "Value is one"); break; case 2: JOptionPane.showMessageDialog(null, "Value is two"); break; default: JOptionPane.showMessageDialog(null, "Other than 1 and 2"); } }}

3.3.1 D whileZ)\ while ;V);Y

initial statementswhile (logical expression) {

statements update statements

}

;\ initial statements Z)\;\UZL\U logical expression ## update statements Z)\;\U;\L

Z)\ while ZJZ)\Z)\;\L;\VL5 { } ;\##);Ly Z)\;\VL5 { } U;Z)\;\L \;\L##U;Ly5 )YUZZ)\;\VL5L;;\YJ Z)\ while ;y##U )V;\ 3.9

3.9 while

. UJ 81

)LUZ)\ while \#UL Hello World )Y ;);Yint count = 1;while(count

3.3.2 D do..whileZ)\ do..while yZ)\;\yUZYZ;\;ZU)Z)\ while ;V Z

)\);Yinitial statementsdo {

statementsupdate statements

} while(logical expression);

;##ZZ)\;Y)V;\ 3.11 ULZ)\ while )Z)\ do..while Z)\ do..while ZZ)\5 { } LUx\)YUxZ\## ;\Z)\ while Z\##Lx\;LyxZZ)\5 { }

3.11 do..while

)LUZ)\ do..while \#UL Hello World )Y;);Yint count = 1;do {

System.out.println(Hello World); count++;

} while(count

( 3.6 )() do..while

;\ 3.6 )LUZ)\ do..while \#L) 1 x 10 x\U)#L;);\ 3.5

3.3.3 D forZ)\ for yZ)\;\yUZYZ ;\;VZ)\);Y

for(initial statements; expression; update statements) {statements

}

;##ZZ)\;YL;)##Z)\ while V;\ 3.9 Z)\ for U;;\Z)YZYZ;\L LZ)\ while do..while U;;\LZ)YZYZLU

)LLZ)\#U Hello World )Y UZ)\ for LUZ)\ while do..while ;Z)\U);Y

for (int count = 1; count

for (int i = 0, j = 0; i < 4; i++, j += 2) {System.out.println(i + + j);

}

yZ)\;\#L) i j ;\ZxYZ)\ for ;\)Y ) i \LxY;x\ ) j \LxY;

( 3.7 )() for

;\ 3.7 )LUZ)\ for \#) 1 x 10 x\U)#L;);\ 3.5 ;\ 3.6

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( 3.8 )

LUZ)\ for ;;\LZ)YZYZ;\L)LL;\ 3.9 yJL));\;LL 1 x 10 UZJL))YLJL)Y;LL) Math.random() y;\UJLZL 0 x 1 Z)\

. UJ 85

public class SampleFor { public void showDemo() {

for (int i=1; i

i = (int)(Math.random()*10) + 1; yZ)\;\UJL)L 1 x 10 UZLU)) i ;Y;L

UZ)\ while U LL;\;UZ)\ for \LZ)Y;\UJL);\LU

3.9 JL));\;LL 1 x 10

3.4 (Nested Structure)

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for (int i = 1; i

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( 3.10 )() for

3.12 * 3.10

;\ 3.11 )L;\;Z)\U VVL ;YJLZ5L U#) (Prime Number) ;\VLL)Y)Y x\V;\ 3.13 )L)#;\U);\ 3.11

. UJ 87

public class NestedFor { public void showDemo() {

for (int i=1; i

( 3.11 )()1

3.13 %* 3.11

3.4.1 D break, continue label Z)\ break continue yZ)\;\UUZYZ \;\JZZ)\5 { } Z)\ break ZUJYJZUZYZ LZ)\ continue UZZ)\;\5 { } \ZYZLL

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Z)\ continue );Yfor (int i = 1; i

;;\UJZZ)\UJ;\VL UZ label xY ))L;\ 3.13 x\Z label ;\\ outer ;Z)\ break outer; \;\ZUJZZ)\ for U)#)V;\ 3.15

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3.15 * 3.13

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Z)\UJ yZ)\;\UZZ)ZZ)\L ;V UZ) UZ UZYZ

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#y5 LZ)\ if L;ZZ)\U##y5

90 UJ .

public class SampleBreak2 {public void showDemo() {

int i, j, product;outer: for (i=1; i

Z)\ if if..else ;\UVLUZ)\ if if..else \U Z)\ switch ;)UZUx)Z)\ if..else if..else .. L

UV);\ZU)Z)\ switch Uy char, byte, short int L)Y

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