Lap Trinh Java Coban

8/13/2019 Lap Trinh Java Coban

1/441

1

Lp trnh Java cbn

Cao c Thng - Trn Minh [email protected], [email protected]


2/441

2

Bi 1. Tng quan lp trnh Java

Gii thiu ngn ngJava

Kin trc ca Java Ni dung mt chng trnh Java c bn Cc kiu d liu c bn & ton t Cc cu trciu khin Nhp d liu tbn phm

Cng c son tho Bi tp


3/441

3

Gii thiu ngn ngJava

Lch spht trin ca Java

Ra i ti Sun Microsystems bi James Gosling 1991: Version u tin vi tn Oak 1995: Tn chnh thc l Java

Mcch ca Java Dng pht trin ng dng cho cc thit bin tthng minh

To cc trang web c ni dung ng (web applet) Hin nay, Java c sdng pht trin nhiu

loing dng khc nhau: cs d liu, mng,Internet, vin thng...


4/441

4

Gii thiu ngn ngJava

cim ca Java

n gin Hngi tnga nhim

An ton Garbage Collection My o (bin dch v thng dch)

Kh chuyn (Portability) Phn tn


5/441

5

Kin trc ca Java

Java Platform Java Virtual Machine (Java VM) Java Application Programming Interface (Java API)

Hardware-Platform

Java VM

Java API

myProgram.java

Java Platform

M ngun


6/441

6

Kin trc ca Java

Java Development Kit JDK

B cng c pht trin Java (jdk) gmtrnh bin dch, thng dch, tr gip, sonti liu v cc thvin chun

Ngoi ra cn mt sthvin khc nhJSP, JavaMail, Java TAPI

1995: Version JDK 1.0 1998: Version JDK 1.2 (Java 2ndPlatform) 2004: Version JDK 1.5


7/441

7

Pht trin ng dng Java

Hai loing dng Java

Application: ng dng c lp Applet: ng dng chy trn Web

Thvin lp Java

B JDK bao gm rt nhiu lp chun c xy dng sn. Lp trnh vin thng sdng cc lp

chun pht trin ng dng.


8/441

8

Pht trin ng dng Java

Cc bc pht trin

`

public class Hello {

public static

}

Hello.java

Bin dch

Thng dch

-----------------------

------------------

------------------------

Hello.class

(bytecode)

javac Hello.java

java Hello01001011


9/441

9

Mt chng trnh Java c bn

1 // Tn file : Hello.java2 /* Tc gi : Cao c Thng*/3

4 public class Hello

5 {

6 // Phng thc main, im btu ca chng trnh7 public static void main( String args[ ] )

8 {

9 System.out.println( Hello World" );10

11 } // Kt thc phng thc main12

13 } // Kt thc lp Hello

Du hiu ch thch =>Lm cho chng trnh dhiu hn. Trnh bin dch sb qua nhng dng c du

ch thch

Khai bo lp

Mi CT phi c t nhtmt khai bo lp

Tn lp cha hm main phiging tn file

im btu v kt thc ca lp

Phng thc main() s c giutin. Mi CT thc thi phi c mtphng thc main()Hin th dy k t ra mn hnh

Cc cu lnh phi kt thc bng du chm phy


10/441

10


Bin dch chng trnh

Vo ch Console ca Windows G cu lnhj a v a c H e l l o . j a v a Nu khng c thng bo li, file Hello.class

s c to ra Thc thi chng trnh G cu lnhj a v a H e l l o(khng cn .class)


11/441

11


Thayi cch hin th

public class Hello{

public static void main(String args[])

{

System.out.print( Chao\tmung\nban\nden\tvoi\nlap trinh Java\n" );}

}

Chao mung

banden voi

lap trinh Java


12/441

12

Cc kiu d liu c bn

Java c hai kiu d liu

D liu gc chun: L cc kiu d liucnh ngha trong ngn ngnhsnguyn, sthc, k t, logic

D liu dn xut: Do ngi dng t nhngha nhmng, lp, giao tip

V d khai bo bin

int x; Person ps;


13/441

13

Cc kiu d liu c bn

Kiu snguyn

Kiu sthc

-264264 164 bitslong

-232232 132 bitsint

-327683276716 bitsshort

-2562558 bitsbyte

Khong gi trKch thcKiu

-1.7e3081.7e30864 bitsdouble

-3.4e383.4e3832 bitsfloatKhong gi trKch thcKiu


14/441

14

Cc kiu d liu c bn

Kiu boolean: Nhn gi tr true hoc false Kiu char: Kiu k ttheo chun Unicode

Mt shng k t

Nhyn\

Du enter\r

Xung hng\n

Tab ngang\tK tUnicode\uxxxx

nghaHng


15/441

15

Cc kiu d liu c bn

Kiu mng Khai bo: int[] iarray; hoc int iarray[]; Cp pht: iarray = new int[100]; Khi to:

int[] iarray = {1, 2, 3, 5, 6};char[] carray = {a, b, c};

Ch : Lun khi to hoc cp pht mng trc khisdng

Mt skhai bo khng hp l:int[5] iarray;int iarray[5];


16/441

16

Cc kiu d liu c bn

Kiu mng Truy cp mng

iarray[3] = 0;carray[1] = z;Ch : Chsca mng c tnh t0

Ly sphn tmng: iarray.length


17/441

17

Cc kiu d liu c bn

Quy tct tn bin

Btu bng mt chci, mt du gchdi (_) hoc mt du dollard ($) Khng c khong trng gia tn

Sau k t u c th dng k t, s, dudollard, du gch di Khng trng vi cc tkho V d: a_1234_d, 1awas, _asdc, a sas,

$erd, %ats Ch : Java phn bit chhoa ch thng


18/441

18

Cc ton t

>>>=>>=>>>


19/441


20/441

20

Cc cu trciu khin

Lnh switch

import javax.swing.JOptionPane;public class TestSwitch{

public static void main(String[] args){

char c;String str=JOptionPane.showInputDialog(null,"Nhap vao ky tu?");c = str.charAt(0);


21/441

21

Cc cu trciu khin

Lnh switch

switch(c){case 'a': case 'e': case 'i': case 'o': case 'u':

System.out.println("Ky tu nay la nguyen am");break;

default:System.out.println("Ky tu nay la phu am");

}System.exit(0); // kt thc chng trnh

}}


22/441

22

Cc cu trciu khin

Vng lp for

for(; ; );

// Chng trnh tnh tng cc s l t1 n 100public class TestFor

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

int tong = 0;

for(int i=1; i


23/441

23

Cc cu trciu khin

Vng lp while while ()

;

// Tnh tng cc s l t1 n 100int tong = 0, i = 1;

while (i


24/441


25/441

25

Nhp d liu tbn phm

V d nhp mt snguyn v mt sthc

import java.io.*;public class TestInput{

public static void main(String[] args) throws Exception{

BufferedReader inStream =new BufferedReader(new InputStreamReader(System.in));

System.out.print("Nhap mot so nguyen:");

String siNumber = inStream.readLine();int iNumber = Integer.parseInt(siNumber);


26/441

26

Nhp d liu tbn phm

System.out.print("Nhap mot so thuc:");

String sfNumber = inStream.readLine();float fNumber = Float.parseFloat(sfNumber);

System.out.println("So nguyen: + iNumber);

System.out.println("So thuc: + fNumber);}}


27/441


28/441

28

V d vi tng Circle

Cch 2: Sdng mt file vi 2 lp ring bit public class TestCircle { public static void main(String[] args) { Circle c = new Circle(5); System.out.println("Area = " + c.getArea()); System.out.println("Circumference = " + c.getCircum()); } }

class Circle { ... }


29/441

29

V d vi tng Circle

Cch 3: Sdng hai file ring bit // file TestCircle.java public class TestCircle

{ public static void main(String[] args) { ... } }

// file Circle.java class Circle { ... }


30/441

30

Cng c son tho

Notepad

Jbuilder Eclipse EditPlus

JCreator


31/441

31

Ch dn thc hnh

t bin mi trng PATH: Trong Windows: Nhy phi trn My

Computer, chn Properties, chnAdvanced, chn Enviroment Variables,chn bin PATH v edit, thm vo ng

dn ti thmc bin ca b JDK. Trong ch Console: G lnh

set Path=%Path%;ng dn ti bin

Nn tham kho java/docs khi lm vic


32/441

32

Bi tp

1. Vit chng trnh tnh tinin thoi: Tin thu bao hng thng l 27000. Tpht gi thnht n pht th200 gi

cc l 120 /pht. Tpht gi th201 n pht th400 gi

cc l 80 /pht. Tpht gi 401 n pht cui gi cc l

40 /pht.


33/441

33

Bi tp

2. Vit chng trnh gii phng trnh bc haiax2 + bx + c = 0 vi a,b,c nhp tbn

phm.3. Vit chng trnh nhp vo mt dy cc s

nguyn khc 0, kt thc nhp khi gp s0.

Sau tnh trung bnh cng ca dy s.Tm s ln nht, snh nht ca dy s.4. Vit chng trnh tnh tng

E = 1 + 1/1 + 1/2 + 1/3 + + 1/nvi n nhp vo tbn phm


34/441

34

Bi tp

5. M rng lp Circle : thm d liu to tmhnh trn v phng thc kim tra mt im

cho trc c nm trong hnh trn hay khng.6. Vit chng trnh nhp vo mt hnh trn,

sau pht sinh 100 im ngu nhin v

cho bit c bao nhiu im nm trong hnhtrn va nhp.


35/441

1

Lp trnh Java cbn



36/441

2

Bi 2. OOP trong Java

Cc phng php lp trnh Gii thiu v OOP Ktha (Inheritance)a hnh (Polymorphism)

Giao tip (Interface) Lp tru tng (Abstract) Gi (Packages)

Java vs C++ Bi tp


37/441

3

Cc phng php lp trnh

Step-by-Step Programming Lp trnh tng bc Machine Language, Assembly Language

1101011100111101101000011101110101101110110010101000100100101011...

MOV BX, CSSUB BX, 10hJNE label1LOOP label2...


38/441

4

Cc phng php lp trnh

Procedural Programming Thit ktop-down.

Chng trnh c chiathnh cc hm, th tc.

Pascal, C

Hn ch: dng d liuton cc, kh pht trin,kh m t cc thc th

trong thc t

Program

Proc3

Proc1

Proc2


39/441

5

Cc phng php lp trnh

Object-OrientedProgramming Chng trnh bao gm

cc i tng. Cc itng tng tc vi

nhau thng qua ccphng thc ca chng D m t cc thc th

D pht trin, m rngchng trnh

Object A

Object CObject B

Object D


40/441

6

Lp trnh hng i tng-OOP

Lp v i tng D liu v cc thao tc trn d liu c kt

hp trong cng mt i tng (object) Lp (class) nh ngha cc tnh cht ca mt

tp hp cc i tng cng kiu

i tng l cc th hin (instances) ca lpc im ca OOP

Tnh ng gi (Encapsulation) Tnh ktha (Inheritance) Tnh a hnh (Polymorphism)


41/441

7

V d v OOP trong Java

Lp Time v TimeTest nm trong cng thmc Lp Time nm trong file Time.java. N cha

cc nh ngha v thi gian. Lp TimeTest nm trong file TimeTest.java.

N dng kim tra lp Time. Lp TimeTest

cha hm main. Khi chy ch cn g:

javac TimeTest.java

java TimeTest Java s tng tm v dch file Time.java


42/441

8

// File Time.javaimportjava.text.DecimalFormat;public class Time{

private int hour; // 0 - 23private int minute; // 0 - 59private int second; // 0 - 59

// Cau tu

public Time() { setTime( 0, 0, 0 ); }// Ham thiet lap du lieupublic void setTime( int h, int m, int s ){

hour = ( ( h >= 0 && h < 24 ) ? h : 0 );minute = ( ( m >= 0 && m < 60 ) ? m : 0 );second = ( ( s >= 0 && s < 60 ) ? s : 0 );

}

Lp Time


43/441

9

// Chuyen sang khuon dang thoi gian quoc tepublic String toUniversalString(){

DecimalFormat twoDigits = new DecimalFormat( "00" );return twoDigits.format( hour ) + ":" +

twoDigits.format( minute ) + ":" + twoDigits.format( second );}

// Chuyen sang khuon dang thoi gian thong thuongpublic String toStandardString(){

DecimalFormat twoDigits = new DecimalFormat( "00" );

return ( (hour == 12 || hour == 0) ? 12 : hour % 12 ) + ":"+ twoDigits.format( minute ) + ":" + twoDigits.format( second )+ ( hour < 12 ? " AM" : " PM" );

}

}// Ket thuc lop Time

Lp Time


44/441

10

Lp Time

D liu Mi d liu phi c mt phm vi nht nh

Phng thc Cu tc tn trng vi tn lp

Cu tkhng c kiu tr v C th c nhiu cu t(overloading) Mi phng thc phi c mt phm vi

nht nh


45/441

11

// File TimeTest.javaimportjavax.swing.JOptionPane;public class TimeTest{

public static void main( String args[ ] ){Time time = new Time(); // Tao mot doi tuong kieu Time

// Lay thoi gianString output = "The initial universal time is: "

+ time.toUniversalString()+ "\nThe initial standard time is: + time.toStandardString();

// Dat lai thoi gian

time.setTime( 13, 27, 6 );output += "\n\nUniversal time after setTime is: "+ time.toUniversalString()+ "\nStandard time after setTime is: "+ time.toStandardString();

Lp TimeTest


46/441

12

// Dat lai thoi giantime.setTime( 99, 99, 99 );

output += "\n\nAfter attempting invalid settings: "+ "\nUniversal time: " + time.toUniversalString()+ "\nStandard time: " + time.toStandardString();

JOptionPane.showMessageDialog( null, output,"Testing Class Time1", JOptionPane.INFORMATION_MESSAGE );

System.exit( 0 );}// Ket thuc ham main

}// Ket thuc lop TimeTest

Lp TimeTest

Ch Ti T t


47/441

13

javac TimeTest.java java TimeTest

Chy TimeTest

Ph i t


48/441

14

Phm vi truy cp

private Ch truy cp c ttrong lp khai bo.

protected Truy cp c ttrong lp khai bo, lp

con ca ca lp khai bo v cc lp cng

gi vi lp khai bo. public Truy cp c tmi ni.

Mc nh Truy cp c ttrong lp khai bo vcc lp cng gi vi lp khai bo.

T kh thi


49/441

15

Tkho this

Tkho this chi tng hin thipublic class Time

{private int hour; // 0 - 23private int minute; // 0 - 59private int second; // 0 - 59

// Viet lai ham setTimepublic void setTime( int hour, int minute, int second ){

this.hour = ( ( hour >= 0 && hour < 24 ) ? hour : 0 );

this.minute = ( ( minute >= 0 && minute < 60 ) ? minute : 0 );this.second = ( ( second >= 0 && second < 60 ) ? second : 0 );

}

N h h khi t


50/441

16

// Ham khoi tao khong tham sopublic Time() { this( 0, 0, 0 ); }

// Ham khoi tao mot tham sopublic Time( int h ) { this( h, 0, 0 ); }

// Ham khoi tao hai tham sopublic Time( int h, int m ) { this( h, m, 0 ); }// Ham khoi tao ba tham sopublic Time( int h, int m, int s ) { setTime( h, m, s ); }

// Ham sao chep

public Time( Time time ){ this( time.hour, time.minute, time.second ); }// Su dung cac cau tuTime t1 = new Time(); // 00:00:00Time t2 = new Time( 2 ); // 02:00:00

Time t3 = new Time( 21, 34 ); // 21:34:00Time t4 = new Time( 12, 25, 42 ); // 12:25:42Time t5 = new Time( 27, 74, 99 ); // 00:00:00Time t6 = new Time( t4 ); // 12:25:42

Np chng hm khi to

Mt s t kho


51/441

17

Mt stkho

Tkho final p dng cho lp, phng thc, bin.

Lp final: l lp khng th c lp conpublic final class NoChild {...}

Bin final: l bin khng th thayi khi

gn gi trprivate final int MAX = 100; Phng thc final: l phng thc khng

th np chngpublic final void NoOverride();

Mt s t kho


52/441

18

Mt stkho

Tkho staticc dng vi phng thc v bin.

Bin static: l bin chung cho miitng ca lp, n c truy cp qua itng ca lp hoc qua tn lp.

private static char TAB = \t; Phng thc static: l phng thc chc php truy cp ti cc bin static ca

lp, n c th gi ngay c khi cha citng no ca lp. public static void Welcome() {...}

K tha (Inheritance)


53/441

19

Ktha (Inheritance)

Ktha l vic xy dng lp mi da trnlp c sn

Lp c sn l lp cha: superclass Lp mi l lp con: subclass

V d: Hnh vung ktha thnh chnht

Con ch ktha t loi ng vt di nc Ch :

Tnh ktha th hin quan his a, khc viquan hhas a (composition)

Composition: mt i tng cha cc i tngthuc lp khc. V d: t c cc bnh xe

Cy k tha


54/441

20

Cy ktha

Animal

Cat Horse Chicken

TerrestrialAnimal AquaticAnimal

Fish Octopus

V d v k tha trong Java


55/441

21

V d v ktha trong Java

Xy dng lp Hnh cu (Sphere) k tha tlp Hnh trn (Circle)

// File Circle.javapublic class Circle{

protected int radius; // radius co the duoc truy cap tu Spherepublic Circle( int radius ){

this.radius = radius;}

public int getRadius() { return radius; }

public double getArea() { return Math.PI*radius*radius; }public double getCircum() { return 2*Math.PI*radius; }

}



56/441

22


// File Sphere.javapublic class Sphere extends Circle{

public Sphere( int radius ){

super(radius);// Goi cau tu cua lop cha}

// Ham tinh dien tich bet mat. Nap chong ham getArea()public double getArea(){ return 4*Math.PI*radius*radius; }

// Ham tinh the tich

public double getVolume(){ return (4.0d/3)*Math.PI*radius*radius*radius; }}

Sphere k tha tCircle



57/441

23


// File InheritanceTest.javapublic class InheritanceTest{


Circle circle = new Circle(5);Sphere sphere = new Sphere(2);

System.out.println(Radius of circle: " + circle.getRadius());System.out.println("Radius of sphere: " + sphere.getRadius());System.out.println("Area of circle: " + circle.getArea());System.out.println(Area of sphere: " + sphere.getArea());

System.out.println("Volume of sphere: " + sphere.getVolume());}

}

T kho super


58/441

24

Tkho super

Tkho super chi tng ca lp cha super(radius): Gi cu tca lp cha

Question: Thm phng thc tnh din tchmt ct qua tm hnh cu ?

Answer: chnh l din tch hnh trn// Them phuong thuc nay trong lop Spherepublic double getAreaCut() { return super.getArea(); }

// ...

// Ham main, goi Tinh dien tich mat catSystem.out.println(Area cut of sphere: " + sphere.getAreaCut());// ...

a hnh (Polymorphism)


59/441

25


V d:class A{

public void method(){ System.out.println(method of A); }}

class B extends A

{ public void method(){ System.out.println(method of B); }

}

class C extends A{public void method()

{ System.out.println(method of C); }}

// Cu lnh trong mainA a = new A();

a.method();

a = new B();a.method();

C c = new C();a = c;a.method();

// Kt qu mn hnh

method of Amethod of Bmethod of C



60/441

26


Tnh a hnh th hin qua vic: cng mtphng thc nhng c ni dung thc hin

khc nhau trn cc i tng khc nhau. Phng thc gi c xc nh thng quai tng c tham chiu, khng thng

qua kiu khai bo ca tham chiu. Trong Java, cc phng thc lun mang

tnh a hnh.

Lp tru tng (abstract)


61/441

27

Lp tru tng (abstract)

Lp tru tng chc dng lm lp cha chocc lp khc, n khng c cc th hin

(instance). Lp tru tng nh ngha cc thuc tnh chungcho cc lp con ca n.

V d c th thit k lp Hnh trn, Hnhvung... ktha t lp tru tng Hnh. LpHnh c thuc tnh l tn hnh, cc phng thctnh din tch, chu vi...

Lp tru tng


62/441

28

Lp tru tng

Lp tru tng (abstract) thng c t nht mtphng thc tru tng, l phng thc khng cci t.public abstract void draw();

Khai bo lp tru tngpublic abstract class ClassName {}

Cc lp con ca mt lp cha tru tng phi cit tt c cc phng thc tru tng. Nu khngn cng s tr thnh lp tru tng.

Khng th to cc i tng ca mt lp tru

tng nhng c th khai bo bin thuc kiu lptru tng tham chiu n cc i tng thuclp con ca n.

Lp tru tng


63/441

29

Lp tru tngpublic abstract class Shape{

static final double PI = 3.14159;public abstract double getArea();

public abstract double getVolume();}class Circle extends Shape{

double radius;

public double getArea() { return PI*radius*radius; }public double getVolume() { return 0; }

}class Cube extends Shape{

double a, b, c;public double getArea() { return 2*(a*b+b*c+c*a); }public double getVolume() { return a*b*c; }

}

Giao tip (interface)


64/441

30


Giao din ch ra cc tnh cht m mt itng c th c, trong mt ngcnh no .

Mt ngi c th khi nh l mt ngi con, trng l mt sinh vin, lp l mt ngi bn.

Giao din trong Java c thc dng th

hin sa ktha nhtrong C++.



65/441

31

p ( )

Khai bo giao tipinterface Name {...}

Mt giao tip thng ch cha cc hng static vcc phng thc public cha ci t.

Mt giao tip c th tha kmt giao tip khc.

Mt lp c th ci t (implements) mt haynhiu giao tip nhng ch c th tha k(extends) tmt lp.



66/441

32

p ( )

interface Drawable{

public void draw();}

public abstract class Shape {...}

public class Circle extends Shape implements Drawable{...public void draw() {...}

}


67/441

Gi (package)


68/441

34

(p g ) Sdng package cch 1: Khai bo import

V d 1: import Transport.Car; V d 2: import Transport.*;

V d 3: importjava.awt.Point; Point p = new Point(1,2);

Sdng package cch 2: Sdng trc tip

java.awt.Point p = newjava.awt.Point(1,2); javax.swing.JOptionPane.showMessageDialog(...);

Ch : Ch c th truy cp c n cc lp public trong

cc package Package java.lang.* c tng import vo mi

chng trnh

Java vs C++


69/441

35

1. Mt chng trnh Java chy chm hn so vi mtchng trnh C tng ng khong 20 ln.

2. Java khng c kiu lit k (enum), kiu cu trc

(struct) hay hp (union), n ch c class. Mi binhay hm ca Java u nm trong mt class no .

3. Java khng c ton tphm vi (scope) ::

4. C ca cc kiu d liu nguyn thu (primitive) trongJava khng ph thuc vo my. c bit kiu char cc 16 bit (Unicode).

5. Biu thc logic trong Java ch nhn gi tr boolean.

6. Trong Java, mi bin khng thuc kiu nguyn thuu phi to ra bng tkho new.7. Java khng c tin x l (preprocessor)

Java vs C++


70/441

36

8. Java khng c con tr.9. Java khng c hu t(destructor), n ch c phng

thc finalize() c gi bi Garbage Collector.10. Java khng h tri smc nh.11. Java ch h tr ktha n, tt c mi lp u mc

nh ktha t lp Object.

12. Java khng c template.13. Java khng c tkho virtual. Tt c mi phng

thc non-static u lun dng dynamic binding.14. Java khng c qu ti ton t(operator overloading).15. i sca hm lun c xl nhi sgi tr

(value argument)

Bi tp


71/441

37

1. Ci t li cc ni dung l thuyt hc.

2. Xy dng lp Candidate (Th sinh) gm cc

thuc tnh: m, tn, ngy thng nm sinh,im thi Ton, Vn, Anh v cc phngthc cn thit.

3. Xy dng lp TestCandidate kim tralp trn: Nhp vo 10 th sinh In ra thng tin v cc th sinh c tngim ln

hn 15

Bi tp


72/441

38

4. Xy dng lp Point c d liu l 2 tox,y v cc phng thc cn thit. Thm

phng thc toString tr v mt Stringc dng [x, y].5. Xy dng lp Rect c d liu l im trn

tri v di phi. Qu ti cc cu tcung cp nhiu cch khi to. Thm ccphng thc: Kim tra 1 im c nmtrong hnh chnht hay khng. Tnh giao

ca 2 hnh chnht.

Bi tp


73/441

39

6. Xy dng lp TestRect: Sinh ngu nhin 10hnh chnht v tnh giao i mt ca

chng.7. Xy dng lp Triangular c 3 phng thcstatic tnh din tch tam gic theo 3cch khc nhau: cnh y v chiu cao,cng thc Heron, di 2 cnh v gc.

Bi tp


74/441

40

8. Xy dng lp Employee c name vphng thc tru tng l earnings(). Xy

dng lp Boss ktha tEmployee ccch tnh lng l mt khon cnh hngthng. Xy dng lp PieceWorker c cchtnh lng da trn ssn phm lm c,lng mt sn phm l $ 0.5. Xy dnglp CommissionWorker c cch tnh lngl mt khon cnh + tin hoa hng trn

ssn phm bn c, mi sn phmc $ 0.1 hoa hng.

Bi tp


75/441

41

9. Xy dng lp tru tng Animal c d liul name v weight, phng thc o l grow

(tng trng lng).10.Xy dng lp Chicken k tha tAnimal,ci t phng thc o mi ln grow thtrng lng tng 0.3 kg. Xy dng lpSparrow ktha tAnimal, mi ln tngtrng lng 0.05 kg.

11.Xy dng giao din Flyable c phng thc

fly(). Ci t giao din ny trong lpSparrow.


76/441

Lp trnh Java cbn

1


Bi 3. Lp trnh GUI (Applet)
mailto:[email protected]:[email protected]:[email protected]:[email protected]


77/441

2

Gii thiu cc loi ng dng Thvin AWT

To cc appleti tng hoGraphics

Kthut khung hnh ph Bi tp

Hai loing dng Java


78/441

3

Applet Chng trnh Java chy trong mt trang

web nh vo trnh duyt h tr Java. Stand-alone Application

Giao din dng lnh (console): Tng tcvi ngi dng thng qua cc dng k t.

Giao din ho (GUI): Tng tc vingi dng bng nhiu cch khc nhaunhhnhnh, nt nhn, biu tng Vicx lng dng da trn cc skin.

Thvin AWT


79/441

4

AWT (Abstract Windowing Toolkit) L b thvin dng xy dng ccng

dng giao din ho (GUI) Cc thnh phn giao din ho nmtrong gijava.awt

Cc thnh phn ca AWT


80/441

5

Component

Button TextComponent Container MenuComponent

TextField TextArea Panel Window

Applet Frame Dialog

Menu MenuBar MenuItem

...

Cc thnh phn ca AWT


81/441

6

Cc thnh phn container: dngchav qun l cc thnh phn khc Applet

Frame Dialog

Cc thnh phn khc: nm trong cc thnh

phn containerNt nhn (Button) Thcn (Menu)

vn bn (TextField) Nt chn (Radio button)

Nhn (Label) Danh sch (List)Vng vn bn (TextArea) La chn (Choice)

.

Mt sphng thc ca Component


82/441

7

void setVisible(boolean): hin thhoc n component Dimension getSize(): tr v kch thc ca component void setSize(Dimension): thayi kch thc

void setEnabled(): bt hoc tt component void repaint(): cp nht li component void update(Graphics g): c gi qua repaint()

void paint(Graphics g): c gi qua update() void setBackground(Color): t mu nn ...

Xy dng cc applet


83/441

8

Lp Applet Java c lpjava.applet.Applet ktha

tlp java.awt.Component cho php tora cc applet trong Web. Mi lp applet do ngi dng to ra u

phi ktha tlp Applet.

Xy dng cc applet


84/441

9

V d1: To file TestApplet.java

Dch: javac TestApplet.java

importjava.applet.Applet;importjava.awt.Graphics;

public class TestApplet extends Applet{

public void paint( Graphics g)

{g.drawString(Hello world!, 50, 25);

}}

Xy dng cc applet


85/441

10

Thc thi applet Cch 1: To file TestApplet.html c ni

dung nhsau:

Mfile ny bng trnh duyt WEB Cch 2: Dng cng c appletviewer.

G lnh:appletviewer TestApplet.html


86/441

11

importjava.applet.Applet;importjava.awt.Graphics;

public class TestApplet extends Applet{

public void init() {}

public void start() {}public void stop() {}public void destroy {}public void paint( Graphics g) {}

}


87/441

Hotng ca Applet


88/441

13

Vngi ca mt Applet Np mt applet: appletc khi to v

thc thi Chuyn hoc tr v trang Web: Ccphng thc stop v start s c gi

Np li applet: nhqu trnh np applet Thot khi trnh duyt: phng thc stop

v destroy s c gi

Lp Graphics


89/441

14

java.awt.Graphics l lp cung cp ccphng thc v ho c bn:

ng thng (Line)ng oval (Oval) Hnh chnht (Rectangle)

a gic (Polygon) Vn bn (Text)

Hnh nh (Image) ...


90/441

Lp Graphics


91/441

16

V ng thng public void drawLine(int x1, int y1, int x2, int y2);

V hnh chnht public void drawRect(int x, int y, int width, int height); T mt hnh chnht

public void fillRect(int x, int y, int width, int height); Xo mt vng chnht

public void clearRect(int x, int y, int width, int height);

Va gic public void drawPolygon(int[] x, int[] y, int numPoint); public void drawPolygon(Polygon p);

Lp Graphics

i t j l t A l t


92/441

17

Demoimportjava.applet.Applet;importjava.awt.Graphics;public class DemoRect extends Applet{

public void init(){System.out.println("Demonstration of some simple figures");

}public void paint(Graphics g){

g.drawLine(70, 300, 400, 250);g.drawRect(100, 50, 130, 170);g.fillRect(120, 70, 70, 70);

int[] x = { 280, 310, 330, 430, 370 };int[] y = { 2p0, 140, 170, 70, 90 };g.drawPolygon(x, y, x.length);

}}

Lp Graphics


93/441

18

Lp Graphics

V t / li


94/441

19

V ng trn/elip public void drawOval(int x, int y, int width, int height);

Tng trn/elip public void fillOval(int x, int y, int width, int height);

Vcung trn

public void drawArc(int x, int y, int width, int height,int startAngle, int arcAngle);

Vxu k t

public void drawString(String str, int x, int y); Vnh

public void drawImage(Image img, int x, int y,...);

Lp Graphics

D

import java applet Applet;import java awt Graphics;


95/441

20

Demoimportjava.applet.Applet;importjava.awt.Graphics;

public class DemoOval extends Applet{

public void init(){

System.out.println("Demonstration of some simple figures");}

public void paint(Graphics g){int xstart = 70, ystart = 40, size = 100;g.drawOval(xstart, ystart, size, size);g.drawOval(xstart + (size*3)/4, ystart, size, size);g.drawOval(xstart + size/2, ystart + size/2, size, size);g.drawArc(xstart, ystart, 300, 200, 0, -90);g.drawString("good morning !", xstart + 265, ystart + 90);

}

}

Lp Graphics


96/441

21

Lp Graphics

Demo

import java applet Applet;


97/441

22

Demoimportjava.applet.Applet;importjava.awt.Graphics;importjava.awt.Image;

public class DemoImage extends Applet{public void init(){

System.out.println("Demonstration of imaging");

}public void paint(Graphics g){

Image image = getToolkit().getImage("summer.jpg");

g.drawImage(image, 0, 0, this);}}

Lp Graphics


98/441

23

Cc lp tin ch khc

Lp Point: biu din im trn mn hnh


99/441

24

Lp Point: biu dinim trn mn hnh Lp Dimension: biu din kch thc v

chiu rng v chiu cao ca mt i tng Lp Rectangle: biu din hnh chnht Lp Polygon: biu din a gic

Lp Color: biu din mu sc

Cc lp tin ch khc

Demo

import java.applet.Applet;


100/441

25

Demoimportjava.applet.Applet;importjava.awt.*;

public class DemoColor extends Applet

{ public void paint(Graphics g){

Dimension size = getSize();g.setColor(Color.orange);g.fillRect(0, 0, size.width, size.height);

Color color = new Color(10, 150, 20);g.setColor(color);

g.drawString("I am a colorful string",size.width/2 - 50, size.height/2);

}}

Cc lp tin ch khc


101/441

26

Xl font v

Dat font

import java.applet.Applet;import java.awt.*;


102/441

27

Dat fontimportjava.applet.Applet;importjava.awt. ;

public class DemoFont extends Applet{

public void paint(Graphics g){

Font font = new Font("Arial", Font.BOLD, 30);g.setFont(font);

g.drawString("I am font Arial, bold, size 30", 50, 50);}}

Bi tp ti lp

Bi 1: Sinh 100 ng


103/441

28

Bi 1: Sinh 100 ngthng c tongunhin v mu ngu

nhin

Bi tp ti lp

Bi 2: V s thay i ca mu xanh l cy


104/441

29

Bi 2: Vsthay i ca mu xanh l cy


105/441

Kthut khung hnh ph

V d v s di chuyn b nhy


106/441

31

V dvsdi chuyn bnhy importjava.applet.Applet;importjava.awt.*;

public class DemoMove1 extends Applet{

private int x = 50;private int y = 50;


if(x > 300) x = 50;

g.fillOval(x, y, 100, 100);delay(100);move();

}


107/441

Kthut khung hnh ph

Gii thch l do nhy:


108/441

33

Gii thch l do nhy: Mi ln gi repaint() th update() c gi

update() xo ni dung ca sv gi paint() Khc phc: Vhnh vo mt khung hnh phtrong bnh

thay v vtrc tip ra mn hnh. Khi vxong, khung hnh phc hin thra

mn hnh trong phng thc paint().

Np chng update() trnh vic xo ni dungca s.


109/441

Kthut khung hnh ph

Gii php


110/441

35

Gii phppublic void paint(Graphics g){

//...offGraphics.clearRect(0, 0, 500, 500);offGraphics.fillOval(x, y, 100, 100);g.drawImage(offImage, 0, 0, this);//...

}

public void update(Graphics g){

paint(g);}//...

}

Applet

Kh nng ca Applet


111/441

36

Kh nng ca Applet Applet c t ti mt Server trn mng

Applet c chuyn ti my Client theo mttrang HTML no Khi mt trnh duyt (tng thch vi Java)

nhn c trang web ny, n sti m caApplet v thc thi trn my client

Applet

Gii hn ca Applet


112/441

37

Gii hn ca Applet Khngc np cc thvin hay cc phng

thc sdng m gc (native code). Khngcc v ghi ln cc tp tin ca

myang chy chng. Khngc khing bt k chng trnh

no trn myang chy. Khngcc bt k tnh cht no ca h

thng.

Bi tp

1. Xy dng mt applet v ra mt khunt h h h


113/441

38

y g pp mt nhhnh v sau:

Bi tp

2. V th hm sy = 3*x*x - 6*x+ 1


114/441

39

3. V th hm sy = sin(x)

Bi tp

4. Dng kthut khung hnh phvmtqu bng chuyn ng t do trong mt


115/441

40

qubng chuyn ng tdo trong mtapplet.

5. Mrng bi ton vi 2 qubng.6. Mrng bi ton vi nn applet l mt

hnhnh.7. Mrng bi ton vi qubng l mt hnh

nh v c nhiu qubng chuyn ng

ng thi.

Lp trnh Java c bn


116/441

Lp trnh Java cbn

1

Cao c Thng - Trn Minh Tun

[email protected], [email protected]

Bi 3. Cc thnh phn GUI

Mt v dn gin


117/441

2

g M hnh xl skin

Cc thnh phn GUI cbn Skin chut

Skin bn phm Bqun l trnh by (layout)

Bi tp

V d: Applet tnh tng 2 s

// file TinhTong.javaimportjava.applet.Applet;


118/441

3

p j pp pp ;importjava.awt.*;importjava.awt.event.*;

public class TinhTong extends Applet implements ActionListener{

private TextField txtNum1, txtNum2;private Button button;

// phuong thuc nay duoc goi khi applet khoi taopublic void init(){

txtNum1 = new TextField(8);// tao o nhap so 1txtNum2 = new TextField(8);// tao o nhap so 2button = new Button("Tinh Tong");// tao nut an


Demo

// dua cac thanh phan vao appletadd(txtNum1);


119/441

4

add(txtNum2);add(button);

// khoi tao gia tri cho o nhaptxtNum1.setText("0");txtNum2.setText("0");

// dat nghe su kien bam nutbutton.addActionListener(this);

};

// phuong thuc nay duoc goi khi co mot hanh dong xay rapublic void actionPerformed(ActionEvent event){

repaint();}


Demo

// phuong thuc nay duoc goi khi ve lai cua sopublic void paint(Graphics g)


120/441

5

{int num1, num2, sum;

String s1 = txtNum1.getText();num1 = Integer.parseInt(s1);String s2 = txtNum2.getText();num2 = Integer.parseInt(s2);sum = num1 + num2;g.drawString("Tong cua hai so la: "+sum, 35, 80);

}}


Gii thch appletT tFi ld B tt l l th i


121/441

6

TextField v Button l cc lp thuc gijava.awt

ActionListener v ActionEvent l cc lpthuc gi java.awt.event

TinhTong cn ci t giao din ActionListenerv n strc tip xl skin n ntbutton.addActionListener(this);

C thdng mt lp khc nghe skinthay cho lp TinhTong


122/441

M hnh x l skin

Ba thnh phn chnh ca m hnhEvent source: ngun gy ra s kin


123/441

8

Event source: ngun gy ra skin,thng l cc thnh phn GUI trongchng trnh

Event object: i tng lu thng tin v

skin xy ra Event listener: i tng s nhncthng tin khi c skin xy ra

Event source lu mt danh sch cc Eventlistener v sthng bo cho chng bit mi khic skin xy ra

M hnh x l skin

V d: Ngi dngn mt ntT th ti


124/441

9

To thng tinvskin

EventObjectComponent

Thng bo c skin xy ra

EventListener EventListener

Vic thng bo skin xy ra thc cht l vic gi mt phng

thc ca EventListener vii struyn vo l EventObject.Cc lp con ca EventListener c thcit cc phng thcxl skin.

Mt s lp skin

EventObject (java.util)


125/441

10

AWTEvent

TextEvent ComponentEvent

InputEvent WindowEvent

KeyEvent MouseEvent

ContainerEvent

ActionEvent

(java.awt)

...

(java.awt.event)

Mt slp skin

Skin cp thp: dng cho hu ht ccthnh phn


126/441

11

thnh phn FocusEvent: t/chuyn focus InputEvent: skin phm (KeyEvent) hoc

chut (MouseEvent) ContainerEvent: thm hoc xo cc

component WindowEvent: ng, m, di chuyn ca s

...


127/441

Mt s interface nghe skin

EventListener


128/441

13

ActionListenerContainerListener

ItemListenerFocusListener

TextListenerKeyListener

MouseListener

WindowListener

Cit qun l skin

Xcnhi tng s gy ra skin (eventsource). V d: nt bm.


129/441

14

Xc nh skin cn xl trn i tng

gy skin. V d: n nt. Xcnhi tng nghe skin (event

listener) v cit cc phng thc tngng. V d: chnh applet snghe skin.

ng ki tng nghe trni tng gy

ra skin. V d:button.addActionListener(...);

Cc event source v event object

Event source Event Ch thchButton ActionEvent Nhn nt

Ch kb It E t Ch b h t it


130/441

15

Checkbox ItemEvent Chn, b chn mt item

Choice ItemEvent Chn, b chn mt itemComponent ComponentEvent n, hin, di chuyn

FocusEvent c chn

MouseEvent Tng tc chutKeyEvent Tng tc bn phm

Container ContainerEvent Thm, bt component

List ActionEvent Nhp kp chut mtitem

ItemEvent Chn, b chn mt item

Cc event source v event object

Event source Skin Ch thch


131/441

16

MenuItem ActionEvent Chn mt menu item

Scrollbar AdjustmentEvent Di chuyn thanh cunTextComponent TextEvent Thayi vn bn

TextField ActionEvent Kt thc thayi vn

bnWindow WindowEvent Thayi ca s

Bng tham khoi tng nghe v phngthc cn cit

Event Class ListenerInterface

Listener Methods

ActionEvent ActionListener actionPerformed()


132/441

17

()

AdjustmentEvent AdjustmentListener adjustmentValueChanged()

ComponentEvent ComponentListener componentHidden()componentMoved()

componentResized()

componentShown()ContainerEvent ContainerListener componentAdded()

componentRemoved()

FocusEvent FocusListener focusGained()focusLost()

ItemEvent ItemListener itemStateChanged()


133/441

ng ki tng nghe

ng ki tng nghe ta sdngtn phng thc c cu trc nhsau:


134/441

19

p g

add + loi skin + Listener(lp nghe skin) V d vi nt Button

addActionListener(ActionListener)

V d vi danh sch List addActionListener(ActionListener) addItemListener(ItemListener)

Mt sthnh phn GUI

EventTextComponent

Checkbox

TextField


135/441

20

Object Component

CheckboxGroup

Checkbox

Container

Label

Button

List

Choice

Panel Applet

Nhn (Label)

Nhn c dng trnh by mtchui vn bn ra mn hnh


136/441

21

Mt sphng thc ca Label: public Label(); // to nhn public Label(String s); // to nhn vi ni dung s

public Label(String s, int align); // to v canh l void setText(String s); // t ni dung nhn void setAlignment(int align); // canh lnhn

...

Nhn (Label)importjava.applet.Applet;

importjava.awt.*;public class DemoLabel extends Applet{


137/441

22

{private Label label;

public void init(){

Font font = new Font("Courier", Font.BOLD, 20);label = new Label("Thu nghiem voi Label");label.setFont(font);add(label);

}public void paint(Graphics g)

{ showStatus("Noi dung cua Label la: + label.getText());}

}

Nhn (Label)


138/441

23

Nt nhn (Button)

Mt sphng thc ca Button Button(); // to nt nhn


139/441

24

Button(String s); // to nt nhn c tn s void setLabel(String s); // i tn nt String getLabel(); // ly tn nt nhn

i tng nghe skin nhn nt cncit giao tipActionListener

Nt nhn (Button)importjava.applet.Applet;

importjava.awt.*;importjava.awt.event.*;

public class DemoButton extends Applet implements ActionListener


140/441

25

public class DemoButton extends Applet implements ActionListener{

private Button blueButton;private Button whiteButton;private Button helloButton;

public void init(){

blueButton = new Button("Blue");whiteButton = new Button("White");helloButton = new Button("Hello");

blueButton.addActionListener(this);whiteButton.addActionListener(this);helloButton.addActionListener(this);


141/441

Nt nhn (Button)


142/441

27

vn bn (TextField)

vn bn cho php nhn d liu tbn phm trn mt dng


143/441

28

Mt sphng thc TextField(...); // cc cu t void setEditable(boolean b); // t/tt chnhp

void setEchoChar(char c); // t k thin thi tng nghe cn ci t 2 giao tip

ActionListener

TextListener Ci t phng thc textValueChanged();

vn bn (TextField)importjava.applet.Applet;


public class DemoTextField extends Applet implements ActionListener


144/441

29

p pp p{

private TextField txtEdit;private TextField txtReadOnly;private TextField txtPass;private final String PASSWORD = "Java";

public void init(){

txtEdit = new TextField("Your name here");txtPass = new TextField(12);

txtPass.setEchoChar('*');txtPass.addActionListener(this);txtReadOnly = new TextField("This text is read only");txtReadOnly.setEditable(false);

vn bn (TextField)add(txtEdit);

add(txtPass);add(txtReadOnly);

}


145/441

30

public void actionPerformed(ActionEvent event){if(txtPass.getText().equals(PASSWORD))

txtReadOnly.setText("Password is valid");else

txtReadOnly.setText("Invalid password !");}

}

La chn (Choice)

Choice cung cp kh nng la chn mttrong scc hng mc sn c Mt s phng thc


146/441

31

Mt sphng thc Choice(); // cu t void addItem(String s); // thm item l s String getItem(int index);// ly item c chsindex

String getSeclectedItem(); // tr v item c chn int getSelectedIndex(); // tr v index ca item

c chn

Lp nghe cit giao tip ItemListener Ci t phng thc itemStateChanged(...)

La chn (Choice)importjava.applet.Applet;


public class DemoChoice extends Applet implements ItemListener


147/441

32

{

private Choice choice;private TextField txtText;private Font font;

public void init(){choice = new Choice();choice.addItem("TimesRoman");choice.addItem("Courier");

choice.addItem("Helvetica");choice.addItemListener(this);

La chn (Choice)txtText = new TextField("Sample Text", 16);

txtText.setEditable(false);font = new Font(choice.getItem(0), Font.PLAIN, 12);txtText.setFont(font);


148/441

33

add(choice);add(txtText);

}

public void itemStateChanged(ItemEvent event){

font = new Font(choice.getSelectedItem(), Font.PLAIN, 12);txtText.setFont(font);

}}

Checkbox (Hpnh du)

Checkbox cung cp cc hp tu chncho ngi dng


149/441

34

Mt sphng thc Checkbox(...); // cc cu t void setLabel(String s); // t nhn mi

boolean getState(); // ly trng thi hin ti Lp nghe cit giao tip ItemListener Ci t phng thc itemStateChanged(...)

Checkbox (Hp nh du)importjava.applet.Applet;


public class DemoCheckbox extends Applet implements ItemListener{


150/441

35

{

private Checkbox checkBold;private Checkbox checkItalic;private TextField txtText;

public void init(){

checkBold = new Checkbox("Bold");checkItalic = new Checkbox("Italic");checkBold.addItemListener(this);

checkItalic.addItemListener(this);txtText = new TextField("Sample Text", 16);Font font = new Font("Courier", Font.PLAIN, 14);txtText.setFont(font);

Checkbox (Hp nh du)add(txtText);

add(checkBold);add(checkItalic);

}

bli id it St t Ch d(It E t t)


151/441

36

public void itemStateChanged(ItemEvent event)

{int valBold = Font.PLAIN;int valItalic = Font.PLAIN;if(checkBold.getState()) valBold = Font.BOLD;

if(checkItalic.getState()) valItalic = Font.ITALIC;Font font = new Font("Courier", valBold + valItalic, 14);txtText.setFont(font);

}}

Checkbox v CheckboxGroup

Cc Checkbox c thc t trongmt CheckboxGroup to ra ccradio button


152/441

37

radio button. V d: To 3 radio button

// To 3 radio button thuc cng mt nhm. Ban u

// radio1 c chn. Ti mi thi im chc thchn mt// trong 3 radio.CheckboxGroup g = new CheckboxGroup();Checkbox radio1 = new Checkbox(Radio1, g, true);

Checkbox radio2 = new Checkbox(Radio2, g, false);Checkbox radio3 = new Checkbox(Radio3, g, false);

Checkbox v CheckboxGroup// Cac import can thiet...

public class DemoRadio extends Applet implements ItemListener{

private Checkbox plain, bold, italic;private CheckboxGroup group;


153/441

38

p p g p;

private TextField txtText;public void init(){

group = new CheckboxGroup();

plain = new Checkbox("Plain", group, true);bold = new Checkbox("Bold", group, false);italic = new Checkbox("Italic", group, false);

txtText = new TextField("Sample Text");

txtText.setFont(new Font("Courier", Font.PLAIN, 14));plain.addItemListener(this);bold.addItemListener(this);italic.addItemListener(this);

Checkbox v CheckboxGroupadd(txtText);

add(plain);add(italic);add(bold);

}


154/441

39

public void itemStateChanged(ItemEvent event){

int mode = 0;if(event.getSource() == plain) mode = Font.PLAIN;

if(event.getSource() == italic) mode = Font.ITALIC;if(event.getSource() == bold) mode = Font.BOLD;txtText.setFont(new Font("Courier", mode, 14));

}}


155/441


156/441

Danh sch (List)public void itemStateChanged(ItemEvent event)

{ List list = (List) event.getSource();showStatus("Item " + list.getSelectedIndex() + " selected");

}public void actionPerformed(ActionEvent event)


157/441

42

public void actionPerformed(ActionEvent event){

List list = (List) event.getSource();String s = list.getSelectedItem();if(s.equals("White")) setBackground(Color.WHITE);

if(s.equals("Black")) setBackground(Color.BLACK);if(s.equals("Yellow")) setBackground(Color.YELLOW);if(s.equals("Green")) setBackground(Color.GREEN);repaint();

}}

Cc skin chut

qun l cc skin chut cn cit giao tip MouseListener


158/441

43

ouse s e e

MouseMotionListener

Cc phng thc ca MouseListener

void mousePressed(MouseEvent e); void mouseClicked(MouseEvent e); void mouseReleased(MouseEvent e);

void mouseEntered(MouseEvent e); void mouseExited(MouseEvent e);

Cc skin chut

Cc phng thc ca MouseMotionListener void mouseDragged(MouseEvent e); void mouseMoved(MouseEvent e);


159/441

44

i tng MouseEvent Cha cc thng tin v skin chut

V d: Chng trnh vn gin

Cc skin chut

// Cac import can thiet...

public class DemoMouse extends Applet implements MouseListener{private Rectangle[] rects;private final int MAX_RECT = 100;


160/441

45

private int numRects;public void init(){

rects = new Rectangle[MAX_RECT];

numRects = 0;addMouseListener(this);setForeground(Color.RED);

}

public void paint(Graphics g){for(int i=0; i< numRects; i++)

g.fillRect(rects[i].x, rects[i].y, rects[i].width, rects[i].height);

}


161/441

Cc skin chut


162/441

47

Cc lp adapter

Khi dng giao tip MouseListener ta phicit tt c cc phng thc ca n,ngay c khi ta ch dng mt trong s .


163/441

48

Java cung cp mt s lp cit snnhng phng thc ny gi l cc lpAdapter). Ta ch cn tha k, citphng thc cn thit. Cc lp adaptercng nm trong gi java.awt.event


164/441

Cc skin bn phm

Mt lp mun nghe skin bn phmphi cit giao tip KeyListener void keyTyped(KeyEvent e);


165/441

50

void keyPressed(KeyEvent e); void keyReleased(KeyEvent e);

Ch : C thsdng KeyAdapter thay chodng giao tip KeyListener

Cc skin bn phm// Cac import can thiet...

public class DemoKey extends Applet implements KeyListener{private String key;


166/441

51

public void init(){addKeyListener(this);key = "";

}


g.setFont(new Font("Arial", Font.BOLD, 72));

g.drawString(key, 100, 100);}

Cc skin bn phm

public void keyTyped(KeyEvent e){key = "" + e.getKeyChar();repaint();


167/441

52

}public void keyPressed(KeyEvent e) {}public void keyReleased(KeyEvent e){}

}

Bi tp ti lp

Bi 1: Vit mt applet thc hin cng vicsau: khi chut c di chuyn vo applet ththng bo Hello Mouse, khi ra khi applet


168/441

53

th thng bo Goodbye Mouse Bi 2: Vit mt applet cho php vngthng bng chut (ging MS Paint)


169/441

Lp FlowLayout

Cc thnh phn c a vo ttrisang phi, theo tng dng, nu htdng ssang dng mi.


170/441

55

Lp FlowLayout

Mt sphng thc ca FlowLayout FlowLayout(...); // cc cu t void setAlignment(int align); // cn l


171/441

56

public void init(){

// tao flow layout can le phaiFlowLayout layout = new FlowLayout(FlowLayout.RIGHT);

setLayout(layout);add(new TextField(15));add(new Button(Press me));

}

Lp BorderLayout

BorderLayout sp xp cc thnh phntheo 5 vng: EAST, WEST, SOUTH,NORTH, CENTER


172/441

57

Lp BorderLayout// ...

public void init(){// tao border layoutsetLayout(new BorderLayout());add(new Button(Up), BorderLayout.NORTH);


173/441

58

add(new Button(Left), BorderLayout.WEST);add(new Button(Right), BorderLayout.EAST);add(new Button(Down), BorderLayout.SOUTH);add(new Label(WELCOME, Label.CENTER),

BorderLayout.CENTER);}

Ch : Khi add mt component theo

BorderLayout cn chr vng, nu khngcomponent skhng c hin th.

Lp GridLayout GridLayout sp xp cc thnh phn trong

mt li c hng v ct. Kch thc cccomponent trong GridLayout l nhnhau.


174/441

59

private Button[] b;public void init(){

// tao grid layoutb = new Button[6];

b[0] = new Button("one");b[1] = new Button("two");b[2] = new Button("three");b[3] = new Button("four");

b[4] = new Button("five");b[5] = new Button("six");setLayout( new GridLayout(3,2) );for(int i=0; i


175/441

60

khung cha.Label 1

Label 2

Button

TextField

Container

Component

Lp Panel (Vng cha) Lp Panel ktha tContainer. N c

thc dng to ra cc giao dintheo mun.


176/441

61

V d: Mt giao din c thc nhiupanel sp xp theo mt layout nhtnh, mi panel li c cc componentsp xp theo mt layout ring.

Ch : Panel c bcc mc nh l

FlowLayout.


177/441

Bi tp

1. Vit applet cho php nhp 3 hsa, b, c(bng TextField) sau gii phng trnhax2 + bx + c = 0 v in kt qu.

2 Vit l t h h h 3 h b


178/441

63

2. Vit applet cho php nhp 3 hsa, b, cv 2 cn x1, x2 sau vthhm sax2+ bx + c = 0 trong on [x1, x2].

3. Vit applet to 3 nt bm. Bm nt 1 thvngu nhin 100 ng thng ra mnhnh. Bm nt 2 th vngu nhin 50 hnh

trn. Bm nt 3 th vngu nhin 50 hnhvung.


179/441

Bi tp

5. Vit applet cho php ngi dng vcc hnh chnht bng chut. Khi ngi dng n chut, kov sau thchut th mt hnh chnht tngng sc vra.M rng chng trnh: to 4 radio cho php


180/441

65

Mrng chng trnh: to 4 radio cho phpchn vOval, Rectangle, Fill Oval, Fill Rectangle.

6. Vit chng trnh cho php ngi dng iukhin mt qubng. Trn mn hnh c cc ntl: To, Nh, Tri, Phi, Ln, Xung. Khi ngidng n 1 nt th kch c/vtr ca qubng s

thay i theo. Yu cu to mt lp Ball ringbit.

Bi tp

7. Vit chng trnh m ttr chi d mn.Trn mn hnh c 3x3 nt bm v mi ntc thl c mn hoc khng (ngu nhin).

Khi ngi dng nhn mt nt nu nt kh th h h i d


181/441

66

Khi ngi dng nhn mt nt, nu nt khng c mn th cho php ngi dng ntip, cn khng th thng bo mn n v

dng li. Lu l mi nt c mt svngi dng c thnhn phm stng ngthay v nhn chut vo nt.

Lp trnh Java cbn


182/441

1


Bi 5. GUI nng cao

TextArea, Canvas CardLayout, GridBagLayout

Frame Menu Dialog


183/441

2

Frame, Menu, Dialog Scrollbar v ScrollPane

Gii thiu cc thnh phn Swing Phng php thit kMVC Bi tp

Cc thnh phnc gii thiuObject

Scrollbar Canvas Container TextComponent

Component


184/441

3

Frame

p

Window TextArea

Dialog

FileDialog

Vng vn bn (TextArea)

Cho php ngi dng nhp vo nhiudng vn bn. Toi tng TextArea

TextArea();


185/441

4

TextArea();

TextArea(int rows, int columns);

TextArea(String s); TextArea(String s, int rows, int columns);

Cc phng thc khc ging nhTextField

Vng vn bn (TextArea)// Cac import can thiet...public class DemoTextArea extends Applet implements ActionListener{

private TextArea textArea1, textArea2;private Button copy;

public void init(){


186/441

5

p (){

textArea1 = new TextArea("Sample Text", 5, 20);textArea2 = new TextArea(5, 20);

copy = new Button("Copy >>>");setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));copy.addActionListener(this);add(textArea1);add(copy);

add(textArea2);}

Vng vn bn (TextArea)public void actionPerformed(ActionEvent event){

textArea2.setText(textArea1.getText());}

}


187/441

6

Khung v (Canvas)

Khung vl mt vng chuyn vho, n khng bche bi cc thnh phngiao din khc.

Khung v c th x l cc s kin ging


188/441

7

Khung vc thxl cc skin gingnhApplet.

sdng khung v, cn to mt lpkhc dn xut tCanvas v cit npchng phng thcpaint().

Nn gi setSize cho khung v. Tovl (0,0) tnh trong khung v.

Khung v (Canvas)// Cac import can thiet...public class DemoCanvas extends Applet implements ActionListener{

private Button rectButton;private Button circleButton;private MyCanvas canvas;

public void init()


189/441

8

public void init(){

setLayout(new BorderLayout());

rectButton = new Button("Draw Rectangle");circleButton = new Button("Draw Circle");rectButton.addActionListener(this);circleButton.addActionListener(this);Panel panel = new Panel();

panel.add(rectButton);panel.add(circleButton);


190/441

Khung v (Canvas)

class MyCanvas extends Canvas{

private int shape;public void paint(Graphics g){

Dimension size = getSize();

g.setColor(Color.BLUE);if (shape == 1)


191/441

10

if(shape == 1)g.fillRect(40, 40, size.width-80, size.height-80);

else if(shape == 2)

g.fillOval(40, 40, size.width-80, size.height-80);}

public void draw(int shape){

this.shape = shape;repaint();

}}

Khung v (Canvas)


192/441

11


193/441

Thanh trt (Scrollbar)

Bi tp: Vit chng trnh cho php iukhin font chthng qua thanh trt. Khithanh trt thay i th cchhin th

(drawString) thay i theo.


194/441

13

Khung cun (ScrollPane)

Khung cun l mt container cho phpcha thnh phn GUI c kch thc lnhn chnh n.

Bi tp: Vit chng


195/441

14

trnh cho php vtrong mt canvas crng ln hn kchthc ca applet.t canvas votrong mt scrollpane.

Bcc nng cao

CardLayout Sp xp cc thnh phn

ging nhcc l bi. Ti

mi thi im chl biu tin c hin th


196/441

15

u tin c hin th. Mi l bi thng l mt

Panel v trn c thdng bt kmt bccno.


197/441

Khung cha Frame

Frame c dng xy dng cc ngdng GUI chy c lp. Frame l mt ca s c thanh tiu v

ccng bin. Bcc mc nh caFrame l BorderLayout


198/441

17

Frame l BorderLayout.

Frame ktha tWindow, n c thnghe cc skin xy ra trn ca skhici t giao tip WindowListener.

Cc ng dng c lp thng to ra casktha tlp Frame.

V dvFrameimportjava.awt.*;

importjava.awt.event.*;

public class DemoFrame{


Frame frame = new Frame(Example on Frame);


199/441

18

Frame frame new Frame( Example on Frame );Label label = new Label("This is a label in Frame",

Label.CENTER);

frame.add(label, BorderLayout.CENTER);frame.setSize(500,500);frame.setVisible(true);frame.addWindowListener(new MyWindowListener());

}}

V dvFrame// Lop nghe doc lap (external listener)class MyWindowListener extends WindowAdapter{

public void windowClosing(WindowEvent event){

System.exit(0);}


200/441

19

}

V dvFrame

importjava.awt.*;

importjava.awt.event.*;public class DemoFrame2{

public static void main(String[] args)

{MyFrame myFrame = new MyFrame("Example on my frame");


201/441

20

myFrame.setSize(250, 300);myFrame.setVisible(true);

myFrame.addWindowListener(new WindowAdapter(){// Lop nghe noi khong ten (anonymous inner class listener)public void windowClosing(WindowEvent e){

System.exit(0);

}});

}}

V dvFrameclass MyFrame extends Frame

{ public MyFrame(String title){

super(title);}

public void paint(Graphics g)


202/441

21


g.setColor(Color.BLUE);

g.fillOval(40, 40, 80, 80);}

}

Ci t listener

Lp nghe c lp: Lp nghe skin l mt lpkhc vi lp cha giao din.

Lp nghe ni khng tn: Lp nghe khng c

tn, chnh ngha phng thc xl skin(actionPerformed)


203/441

22

(act o e o ed)

Lp nghe ni c tn: Lp nghe c khai bo

nm trong mt lp khc. Lp ni c thtruy xut cc phng thc, d

liu ca lp cha n (outer class)

Dng lp nghe ni c tn l mt kthut phbin.

Khung cha Frame

To cc thnh phn GUI v xl skintrong Frame cng ging nhtrong Applet. Ch :

Frame khng c cc phng thc init, startnh trong Applet.


204/441

23

nhtrong Applet. Cc ng dng c lp dng Frame phi c hm

main vc chy trc tip bng lnh java Cn c lnh setSize, setVisible(true)c th

hin thFrame.

cui chng trnh nn c lnh:System.exit(0);

Bi tp ti lp

Bi 1: Vit li chng trnh Tnh Tng 2ssdng Frame. Bi 2: Mrng bi 1 khi ngi dng

ng ca sth sxut hin mt thngbo xc nhn vic ng


205/441

24

bo xc nhn vic ng.

DngJOptionPane.showConfirmDialog

Thc n (Menu)

Object

MenuComponent

M I M B


206/441

25

MenuItem MenuBar

Menu CheckboxMenuItem

Thc n (Menu)

MenuBarMenu


207/441

26

Separator

MenuItem

Thc n (Menu) To thc n

To v gn MenuBar vo ca s MenuBar menuBar = new MenuBar();

myFrame.setMenuBar(menuBar);

To Menu v gn vo MenuBar Menu fileMenu = new Menu(File);


208/441

27

( );

menuBar.add(fileMenu);

To MenuItem v gn vo Menu MenuItem openItem = new MenuItem(Open);

fileMenu.add(openItem);

To ng phn cch fileMenu.addSeparator();

Thcn (Menu)

X l skin trn cc MenuItemi tng nghe cc MenuItem phi citgiao tip ActionListener

Tham kho thm v CheckboxMenuItem


209/441

28

CheckboxMenuItem

PopupMenu


210/441

Hp hi thoi (Dialog)

Dialog ktha tlp Window, n c bcc mc nh l BorderLayout.

Hp thoi c thcha cc thnh phn

GUI v xl cc skin nhmt ca sbnh thng.


211/441

30

g


212/441

V dvFrame, Menu v Dialog


public class DemoFrame3{

public static void main(String[] args

{MyFrame myFrame = new MyFrame("Example on my frame");myFrame.setSize(500, 400);


213/441

32

myFrame.setSize(500, 400);myFrame.setVisible(true);

myFrame.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){

System.exit(0);

}});

}}


class MyFrame extends Frame implements ActionListener{

private MenuBar menuBar;private Menu menu;private MenuItem circleItem, rectItem;

public MyFrame(String title){

super(title);


214/441

33

super(title);menuBar = new MenuBar(); setMenuBar(menuBar);

menu = new Menu("Draw"); menuBar.add(menu);

circleItem = new MenuItem("Circle");rectItem = new MenuItem("Rectangle");menu.add(circleItem);

menu.add(rectItem);circleItem.addActionListener(this);rectItem.addActionListener(this);

}


public void actionPerformed(ActionEvent e){

if (e.getSource() == circleItem){ MyDialog dialog = new MyDialog(this,

"Modeless Dialog: Circle", false);}

}}

class MyDialog extends Dialog


215/441

34

class MyDialog extends Dialog{

MyDialog(Frame parent, String title, boolean isModel){

super(parent, title, isModel);add(new Label("Hi, I am a dialog"), BorderLayout.CENTER);

setSize(300, 200);setVisible(true);addWindowListener(new MyDialogListener(this));

}};

V dvFrame, Menu v Dialog// Co the dat lop nay lam lop noi (inner class) cua lop MyDialog

class MyDialogListener extends WindowAdapter{Dialog dialog;

MyDialogListener(Dialog dia)

{dialog = dia;

}


216/441

35

}

public void windowClosing(WindowEvent e){

dialog.setVisible(false);dialog.dispose();

}}

Gii thiu JFC

JFC (Java Foundation Class) L thvin lp trnh giao din hopht trin da trn thvin AWT

JFC cung cp kh nng to giao din linhng, uyn chuyn hn so vi AWT


217/441

36

JFC c sn trong cc phin bn tJdk 1.2

tri. Cc lp ca JFC nm trong gijavax.swing

Cc thnh phn Swing

Cc thnh phn GUI ca Swing thngbt u bi chJ: JButton, JLabel, JTextArea, JFrame,

JPanel, JCheckBox, JRadioButton, JList,JComboBox, JScrollPane


218/441

37

Cc thnh phn mrng nh:

JTabbedPane, JProgressBar, JTable, JTree Vic xl skin trn cc thnh phn

Swing ging nhtrn cc thnh phnAWT.

V dv Swing

importjava.awt.*;importjavax.swing.*;

public class HelloJFC{


JFrame frame = new JFrame("JFC");Icon icon = new ImageIcon("rose.gif");JButton button = new JButton("Rose", icon);


219/441

38

J utto butto e J utto ( ose , co );button.setMnemonic('R');

button.setToolTipText("Button Rose");

frame.getContentPane().setLayout(new FlowLayout());frame.getContentPane().add(button);frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);frame.setSize(400, 300);frame.setVisible(true);

}}

V dv Swing


220/441

39

Thit kchng trnh Cc thnh phn ca chng trnh

Dliu ca bi ton cn xl (Model) Hin thdliu ca bi ton thng qua giao

din (View) iu khin tng tc vi ngi dng(Controller)


221/441

40

(Controller)

V d: Chng trnh iu khin qubng Model: Dliu vqubng View: Giao din hin thdliu qubng

Controller: iu khin di chuyn qubng

Thit kchng trnh Model: Dliu vbng gm totm (x,y) v

bn knh bng. View: Giao din hin thgm c hnh qubng

v 2 nt iu khin.

Controller: Khi n nt iu khin th qubng dichuyn.


222/441

41

Mt sphng php thit k Big Blob

Tt cModel, View, Controller t trongmt mt lp duy nht.


223/441

42

ControllerModel View

V dvi Big Blob// file TestBall.java tao ra mot big blobpublic class TestBall


MyBallFrame myFrame = new MyBallFrame(Ball Frame);

myFrame.setSize(400, 300);myFrame.setVisible(true);...

}


224/441

43

}}

V dvi Big Blob// MyBallFrame la mot big blob

// No chua ca model, view va controllerclass MyBallFrame extends Frame implements ActionListener{

private int x, y, radius;// du lieu ve qua bong (model)private Button moveLeft, moveRight;// thanh phan GUI (view)

...moveLeft.addActionListener(this);

h dd ( h )


225/441

44

moveRight.addActionListener(this);

...

// xu ly su kien (controller)public void actionPerformed(ActionEvent event)...

}

Mt sphng php thit k Presentation-Model

Tch ring Model v Presentation (gmView + Controller)

ControllerView


226/441

45

ControllerView

Model

V dvi Presentation-Model// file TestBall.java tao model va presentationpublic class TestBall


// tao model

BallModel myBall = new BallModel(50, 50, 20);

// tao presentationBallPresentation myFrame = new BallPresentation(myBall);


227/441

46

y ( y );...

}}

V dvi Presentation-Model// file BallPresentation.java chua view va controller// No co mot thanh phan du lieu la model can xu ly

// Cach 1: Dung top-level listenerpublic class BallPresentation extends Frame implements ActionListener{

private BallModel ball; // model can xu ly

private Button moveLeft, moveRight; // thanh phan GUI (view)...moveLeft.addActionListener(this);moveRight addActionListener(this);


228/441

47

moveRight.addActionListener(this);...

// xu ly su kien (controller)public void actionPerformed(ActionEvent event)...

}

V dvi Presentation-Model

// file BallPresentation.java, cach 2: dung lop nghe la inner classpublic class BallPresentation extends Frame

{private BallModel ball; // model can xu lyprivate Button moveLeft, moveRight; // thanh phan GUI (view)...

moveLeft.addActionListener(new ToLeftListener());moveRight.addActionListener(new ToRightListener());...// xu ly su kien (controller)


229/441

48

class ToLeftListener implements ActionListener

{public void actionPerformed(ActionEvent event){

ball.moveLeft();

repaint();// goi phuong thuc cua lop outer}

}...

}

V dvi Presentation-Model// file BallModel.java chua du lieu va phuong thuc cua qua bong

// Model khong phu thuoc vao Presentationpublic class BallModel{

private int x, y, radius;

BallModel(int x, int y, int radius) ...void moveLeft() ...void moveRight() ...


230/441

49

g ()int getXCenter() ...

int getYCenter() ...int getRadius() ...

}

Mt sphng php thit k Model-View-Controller

Tch ring Model, View v Controller

ControllerView


231/441

50

Model


232/441


233/441

V dvi MVC

// file BallView.javapublic class BallView extends Frame{

private BallModel ball; // model can xu lyprivate Button moveLeft, moveRight;

BallView(BallModel ballModel)

{ ball = ballModel;}

public void paint(Graphics g)


234/441

53

p p ( p g)

{ g.fillOval(...);}// phuong thuc nay duoc goi boi controllerpublic void addToLeftListener(ActionListener al)

{buttLeft.addActionListener(al);

}...

}

V dvi MVC// file BallController.javapublic class BallController

{private BallModel ball; // model can xu lyprivate BallView view; // view can xu ly...BallController(BallModel ballModel, BallView ballView){

// nhan model va view can xu lyball = ballModel;view ballView;


235/441

54

view = ballView;

// dat lang nghe tren viewview.addToLeftListener(new ToLeftListener());view.addToRightListener(new ToRightListener());

}

V dvi MVC// file BallController.java (tiep theo)

// xu ly su kien thong qua inner classclass ToLeftListener implements ActionListener{

public void actionPerformed(ActionEvent event){ball.moveLeft();view.repaint();

}


236/441

55

}

}...

}

V dvi MVC// file BallModel.java chua du lieu va phuong thuc cua qua bong

// Model khong phu thuoc vao View va Controllerpublic class BallModel{

private int x, y, radius;

BallModel(int x, int y, int radius) ...void moveLeft() ...void moveRight() ...int getXCenter()


237/441

56

int getXCenter() ...

int getYCenter() ...int getRadius() ...

}

Case study: Chng trnh i tin

Vit chng trnh cho php tnh slngtin VNtng ng vi mt slng USDcho trc. Bit rng 1 la = 16,798 .

M tgiao din nhsau:


238/441

57

Case study: Chng trnh i tin

ExchangeModel ?

ExchangeView ?

ExchangeController ?

Ci t v thnghim


239/441

58

Ti liu tham kho http://www.dickbaldwin.com/toc.htm

http://leepoint.net/notes-java/index.html

http://java.sun.com/developer/onlineTrainin

g/GUI/Swing2/shortcourse.htm


240/441

59

Bi tp1. Vit chng trnh cho php ngi dng chn

mt trong hai chl Line v Point (dngCheckbox), sau ngi dng c thdngchut vtrong mt Canvas nm giamn hnh (ging MS Paint).

2. Vit li cc chng trnh lin quan tiGraphics s dng Frame


241/441

60

Graphics sdng Frame.3. Vit li cc chng trnh lin quan ti thnh

phn giao din GUI sdng Frame.

Bi tp4. Vit chng trnh to 3 menu trong mt

Frame nhsau:Colors Shapes Help

Red Circle About

Green RectBlue Line

Menu Colors cho php chn mu, menu


242/441

61

Shapes cho php chn hnh. Khi ngi dngchn menu v n nt drawtrn Frame thchng trnh vra hnh v mu c chn.

Menu Help About hin thhp thoi gii thiuvchng trnh.

Bi tp5. Vit chng trnh tnh din tch cc hnh:

To mt Frame trong bn tri c 3 lachn l Circle, Rectangle v Triangular(dng Checkbox). Khi ngi dng chn mttrong cc hnh th bn phi shin thcc nhp liu tng ng: Circle c mt nhpl Radius, Rectangle c 2 nhp l Width v


243/441

62

, g pHeight, Triangular c 3 nhp l 3 cnh a,b, c. Sau ngi dng chn nt Computeth chng trnh tnh v hin thkt qulnmn hnh. (Dng CardLayout)

Bi tp6. Vit chng trnh to 2 menu item l Nhp

hng v Bn hng. Khi ngi dng chnnhp hng th hin thFrame cho php nhpvo tn hng, slng, n gi (lu thngtin ny vo mng). Khi ngi dng chnBn hng th hin thFrame (hoc Dialog)cho php nhp vo tn ngi mua v cho


244/441

63

php chn mua mt trong scc mt hngc sn; sau hin thstin m ngi phi tr. (Thit ktheo MVC)

Lp trnh Java cbn



245/441

1


246/441

X l li v ngoi l

Trong mt sngn ngnhC, vic x l lithng c ci t ngay ti cc bc thchin ca chng trnh. Cc hm s tr v mtcu trc li khi gp li.

V d: Tm kim phn t trong mt danh sch ErrorStruct error = new ErrorStruct();

TableEntry entry = lookup(Marianna, employee, error);


247/441

3

if (entry == null) {

return error;

}

X l li v ngoi l

M lnh v m x l li nm xen k khinlp trnh vin kh theo di c thut tonchnh ca chng trnh.

Khi mt li xy ra ti hm A, tt c cc ligi hm lng nhau n A u phi x l lim A tr v.


248/441

4

X l li v ngoi l

Trong Java, vic x l li c thc ci ttrong mt nhnh c lp vi nhnh chnh cachng trnh.

Li c coi nhnhng trng hp ngoi l(exceptional conditions). Chng cbt/nm (catch and throw) khi c li xy ra.=> Mt trng hp li s chc x l ti


249/441

5

ni cn x l.=> M chnh ca chng trnh sng sa,ng vi thit kthut ton.

V d 1importjava.awt.Point;

public class MyArray{

public static void main(String[ ] args) {

System.out.println("Goi phuong thuc methodeX()");

methodeX();

System.out.println("Chuong trinh ket thuc binh thuong");}

public static void methodeX() {

Point[ ] pts = new Point[10];


250/441

6

for(int i = 0; i < pts.length; i++) {pts[i].x = i;

pts[i].y = i+1;

}

}

}

Kt qu thc thi v d 1

Goi phuong thuc methodeX()Exception in thread "main" java.lang.NullPointerException

at MyArray.methodeX(MyArray.java:14)at MyArray.main(MyArray.java:7)

Gii thch: H thng tung ra mt exception thuc lpNullPointerException khi gp li. Sau chng trnh kt


251/441

7

thc.

V d 2public class MyDivision {

public static void main(String[ ] args) {System.out.println("Goi phuong thuc A()");

A();

System.out.println("Chuong trinh ket thuc binh thuong");

}

public static voidA() {B();

}

public static void B() {


252/441

8

C();}

public static void C() {

float a = 2/0;

}

}

Kt qu thc thi v d 2

Goi phuong thuc A()Exception in thread "main" java.lang.ArithmeticException: / by zero

at MyDivision.C(MyDivision.java:14)at MyDivision.B(MyDivision.java:11)at MyDivision.A(MyDivision.java:8)

at MyDivision.main(MyDivision.java:4)

Gii thch: Phng thc A() gi B(), B() gi C(), C() gy ra li


253/441

9

chia cho 0 v h thng nm ra mt exception thuc lpArithmeticException. Sau chng trnh kt thc.

Ngoi l

Khi mt phng thc gp li no,v d nhchia khng, vt kch thcmng, m file cha tn ti th cc

ngoi l sc nm ra. Chng trnhdng li ngay lp tc, ton b phnm pha sau s khngc thc thi.


254/441

10

Java h tr cch thc x l ngoi l(exception handling) tu theo nhu cuca chng trnh.

X l ngoi l

Khi try/catcht on m c khnng xy ra ngoi ltrong khi try

to

n m x

l ngo

i l

trong kh

icatch

Khi xy ra ngoi l trong khi try, cc culnh trong khi catch sc thc hin


255/441

11

tu vo kiu ca ngoi l. Sau khi thc hin xong khi catch, iu

khin sc tr li cho chng trnh.

Khi try/catch

V d 1:try{

methodeX();

System.out.println(Cau lenh ngay sau methodX());}catch (NullPointerException e){

System.out.println(Co loi trong khoi try);

}


256/441

12

}System.out.println(Cau lenh sau try/catch);

Khi try/catch

t {

try {A();

} catch (Exception e) {

System.out.println(Co loi trong A());}

V d 2:

V d 3:


257/441

13

try { x = System.in.read();System.out.println(x = + x);

} catch (IOException e) {System.out.println(Error: + e.getMessage());

}

Khi try/catch

try{

String s = buff.readLine();

int a = Integer.parseInt(s);x[i++] = a;} catch (IOException e) {

System.out.println(Error IO: + e.getMessage());} catch (NumberFormatException e) {

S stem o t p intln(E o Fo mat + e getMessage())

V d 4:


258/441

14

System.out.println(Error Format: + e.getMessage());} catch (ArrayIndexOutOfBoundsException e) {System.out.println(Error Index: + e.getMessage());

}

Khi finally

Khi mt ngoi l xy ra, chng trnh dngli, mt scng vic dn dp c th skhng c thc hin (v dnhng file).

Khi finally m bo rng cc cu lnh trong

lun c thc hin, k c khi ngoi lxy ra.

try

{


259/441

15

{ doSomething(); // phng thc ny c th gy ra ngoi l} finally {

cleanup();}

Tm tt v x l ngoi l

Cc ngoi l xy ra khi gp li. C th bt v x l cc ngoi l bng cch

sdng khi try/catch. Nu khng chngtrnh s kt thc ngay (vi ng dng

console) hoc tip tc tn ti (vi ng dngGUI).

Khi bt ngoi l, phi bit r kiu ngoi l

cn bt C th dng kiu cha Exception


260/441

16

cn bt. C th dng kiu cha Exception. chc chn vic dn dp lun c thc

hin, dng khi finally. C th kt hp

try/catch/finally.

Mt s lp ngoi l

ClassNotFoundException

Throwable

Error Exception

RuntimeExceptionAssertionError IOException

Object


261/441

17

NullPointerException ArithmeticException

Mt s lp ngoi l

Lp Throwable C mt bin String lu thng tin chi titv ngoi l xy ra

Mt sphng thc c bn Throwable(String s); // To mt ngoi l ctn l s.

String getMessage(); // Ly thng tin vngoi l


262/441

18

ngoi l void printStackTrace(); // In ra tt c cc

thng tin lin quann ngoi l

Mt s lp ngoi l

Lp Exception C nhiu ngoi l thuc lp con caException.

Ngi dng c th to ra cc ngoi l ktha tException.

Lp Error

Ch nhng li nghim trng v khng d


263/441

19

Ch nhng li nghim trng v khng don trc c nhThreadDead,LinkageError, VirtualMachineError...

Cc ngoi l kiu Error t c x l.

Mt s lp ngoi l

RuntimeException: Ch cc ngoi l cth xy ra khi JVM thc thi chng trnh NullPointException: con tr null

OutOfMemoryException: ht b nh ArithmeticException: li ton hc, li chiakhng

ClassCastException: li p kiu


264/441

20

ClassCastException: li p kiu ArrayIndexOutOfBoundsException: vtqu ch smng

...

Hai loi ngoi l

Lap Trinh Java Coban

Documents

Transcript of Lap Trinh Java Coban