giaotrinhjava1234

8/3/2019 giaotrinhJava1234

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GIO TRNH BI GING

MN HC : LP TRNH JAVA


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M U

GII THIU SLC LPTRNH HNG I TNG


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Mc Tiu Bi Hc

Th no l lp trnh hngitng

Tm hiuvtrutngdliu

nhnghalp v itng Constructor v Destructor

Tm hiuv tnh lutr, bao bcdliu,tnh ktha v a hnh

Cc u im caphng php lp trnhhngitng


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Lp Trnh Hng i Tng

Ly i tng lm nn tng c s caphng php lp trnh

Phng php thitk v thchinbng cchphnmm


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Tru Tng D Liu

L tin trnh xc nh v tphp cc tnh chtv cc hnh ng ca mt thc th c lin

quan nngdng Li ch :

Tp trung vo vn

Xc nhnhng tnh cht v hnh ngthityu

Loitrnhng chi tit khng cnthit


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Tru Tng D Liu

Cc tnh chtca mt i

tng Ngi

Tn

a ch

Tui

Chiu cao

Mu tc

Cc tnh cht camt i tng

Khch hng

Tn

a ch


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Tru Tng D Liu (tip theo)

Cc thuc tnh Cc hnh ng

Tn ca khch hng Nhp tn ca khch hng

a ch ca khch hng Nhp a ch ca khch hng

i xe hi mua Nhp i xe hi mua c

Ngi bn xe hi Nhp tn ngi bn xe hi

Lp ho n


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Lp

Lp l mt nhm cc i tng c chungnhng tnh cht v hnh ng

Lp Khch hng

Tn khch hnga ch khch hng

i xe hi mua

Tn ngi bn xe hi

Nhp tnNhp a ch

Nhp i ca xe hi mua c

Nhp tn ca ngi bn xe hi

Lp ha n


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i Tng

i tng l mt th hin ca lp

Ton

Anh

Tun


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i Tng ( tip theo )

Thuc tnh Tnh cht m tmtitng

Hnh ng Dchv m itng c thpng

Phngthc ct cch pngbng hnh ng khi c yu cu

Thng ip Yu cumt hnh ng

Binc

S kch thch titng ny gi sang itng khc


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Lp V i Tng

Lp l mt thc th, cn i tng l mt thcththct

Lp l mt m hnh nimnh r cc tnh chtv cc hnh ng c quy nhbi mt itng, cn itng l mt m hnh thcs

Lp l khun mutitngcto ra

Tt c cc i tng trong cng mt lp c cctnh cht v cc hnh ngnh nhau


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Constructor

Tin trnh to ra mtitngcgi lConstructor

Mt Constructor: Cp pht vng nh

Khi gn nhng thuc tnh (nu c)

Cho php truy cp nhng thuc tnh vphng thc


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Destructor

Tin trnh hy mt i tng gi lDestructor

Mt Destructor:

Gii phngbnh

Cm truy cpthuc tnh vphngthc


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Tnh Lu Tr

Tnh lu tr l khnngca i tng cthlulidliuca n sau khi bhy


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Tnh Bao Bc D Liu

Tin trnh che dunhng chi tithinthcmtitngcgi l tnh baobc

uim: Tt c nhng thuc tnh v phng thc cn

thitucto

Mt lp c th c nhiu tnh cht v phngthcnhngchmts trong chinthcho ngi dng


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Tnh K Tha

LP SINH VIN LP NHNVIN

LP KHCHHNG

Tn Tn Tn

a ch a ch a chim mn 1 Lng Sn phm mua

c

im mn 2 Chc v Nhp tn

Nhp tn Nhp tn Nhp a ch

Nhp a ch Nhp a ch Nhp m sn phmNhp im Nhp lng Lp ha n

Tnh tng s im Tnh lng


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Tnh K Tha (tip theo)

Lp Ngi

Tn

a ch

Nhp tnNhp a ch


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Tnh K Tha ( tip theo )

LP NGI

Tn

a ch

Nhp tnNhp a ch

Thm cc thuc tnh v hnh ngcn thit vo lp khch hng

Nhp m sn phm mua

Lp ha n

Lp Khch Hng+ =


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Tnh K Tha ( tip theo )

Tnh Thak L cch cho php mtlp chia snhngthuc tnh

v nhng hnh ng nh ngha trong mt hocnhiulp khc

Lp con L lpthaktlp khc

Lp cha L lptmtlp khc thak cc ngxca n

athak Khi mtlp con thakt hai hocnhiulp


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Tnh a Hnh

Text Line Picture

How are you?

Hnh ngDisplay

Tnh a hnh l thuc tnh cho php mthnh ng ng x khc nhau trn cc lpkhc nhau


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u im ca phng phphng i tng

Chia s trongphm vi mtngdng y mnh s dng li ca cc i tng

khi hinthcnhngngdngmi V lu di, chi phgimngk Gimli v rcri trongbo tr

iuchnh nhanh hn


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TNG KT

Tip cn hng i tng a ra mt gii phpton din cho mt bi ton cth

Tru tngd liu l mt tin trnh xc nh vtphp cc tnh cht v cc hnh ng c quan hvimtthcthcth

Lp m tmtthcth, cn itng l mtthc

ththct Constructor v Destructor

Tnh lu tr, bao bcd liu, tnh k tha v a

hnh


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Chng 1

Gii thiu ngn ng

lp trnh Java


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Gii thiu

S pht trin ca Java

Hng ti ngi dng

Ging vi C / C++


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Cc c trng ca Java

ngin Hngitng

clpphncng Mnh Bo mt Phn tn

a lung ng


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Cc chng trnh dch

truyn thng


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Chng trnh dch Java


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Java Translation and ExecutionJava source

code

Machinecode

Javabytecode

Javainterpreter

Bytecodecompiler

Javacompiler


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Cc loi chng trnh Java Applets

ngdngclp (console Application)

ngdng giao din (GUI Application)

Servlet

ng dng c s d liu


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My o Java

L mtphnmmda trn cs my tnho

L tp hp cc lnh logic xc nh hotngca my tnh

c xem nh l mthiu hnh thu nh N thitlplptrutng cho:

Phncng bn di Hiu hnh M bin dch


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Qu trnh dch chng trnh Java

Trnh bin dch chuyn m ngun thnh tpcc lnh khng phthuc vo phncng

Trnh thng dch trn mi my chuyn tplnh ny thnh chng trnh thc thi

My oto ra mt mi trngthc thi cclnhbng cch:

Np cc file .class

Qun l b nh

Dnrc


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Trnh dch Java

Java Development Kit Java 1.0

Java 1.1

Java 2

..............


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B cng c JDK

Trnh bin dch, 'javac'

javac [options] sourcecodename.java

Trnh thng dch, 'java' java [options] classname

Trnh dch ngc, 'javap'

javap [options] classname

Cng c sinh ti liu, 'javadoc'

javadoc [options] sourcecodename.java


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Chng trnh tm li - Debug, 'jdb

jdb [options] sourcecodename.javaOR

jdb -host -password [options]

sourcecodename.java

Chng trnh xem Applet ,

'appletviewer appletviewer [options]sourcecodename.java / url


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Cc gi chun ca Java java.langGeneral support java.applet - Creating applets for the web java.awt - Graphics and graphical user interfaces

java.io java.utilUtilities java.net - Network communication java.awt.event

java.rmi java.security java.sql


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Chng 2

Cc kin thc c bn Cu trc chng trnh ca

ngn ng Java


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Cc thnh phn c bn

1. TP K T CA JAVA

2. T KHO

3. TN, LI CH THCH4. CU LNH V DU CHM CU

5. CU TRC CA CHNG TRNH JAVA

6. MT S CHNG TRNH JAVA MU


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Tp k t ca java

Mi ngn ng u c xy dng trn b k t. B k tca Java nh sau:+ Cc ch ci in hoa: A, B, C, Y, Z+ Cc ch ci in thng: a, b, c, y, z+ Cc ch s: 0, 1, 2, ,9

+ Cc du cu: , ; : / ? . [ ] { }! ~ @ # $ % ^ & * ( )- + = < >+ Cc du ngn cch khng nhn thy: du cch, du

tab, du xung hng enter+ Du gch ni di _

Ch :+ Java phn bit ch in hoa v ch in thng.+ C th dng cc k t khc nh , , , , , hay

c ting Vit trong chng trnh Java


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B t kha ca Java


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Tn v Li ch thch

* Tn :- Tn dng xc nh cc i lng khc nhau trongmtchng trnh.- Mi tn c s dng trong chng trnh uphic khai bo.- Tn hpl l dy ktlin nhau, c thgm cc chci (a..,z, A..,Z), cc chs (0..9), ktgchdi (_).- Tnphibtubngch ci hocdugchdi.

- Tn khng c trng vit kho.Vd : Nghiem_x, hoan_doi, y_1, y2,.. l tn hpl.


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Tn v Li ch thch* Lich thch :

- Khng c tc dngto ra m cachng trnh, gip ddng trong vic tm kim,kim tra, sachng trnh

- Li ch thch c th c t bt k u trongchng trnh

- Cch ghi li ch thch:

Cch 1 : Ch thch cho nhiu dng

/* li ch thch

--------------*/

Cch 2 : Ch thch cho mt dng

//li ch thch


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Cu lnh v Du chm cu

Mt cu lnh thnggmphn m td liu v phnlnh theo quy nhca Java. C hai loi:

+ Cu lnhngin: l nhng lnh khng cha cc

lnh khc : lnh gn, lnhgiphngthc, ...+ Cu lnh cu trc: gm khi lnh, lnh r nhnh,lnhlp

Khilnh l gmnhiulnhct trong du { } Cc cu lnh cch nhaubidu; Duchmphy; dng ngn cch cc lnh,ngha l

cuimilnh,mi khai bo u c chmphy


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Cu lnh v Du chm cu

cu lnh

cu lnh n gin

cu lnh cu trc

php gn

li gi phng thc

lnh nhy

khi lnh

lnh la chn

lnh lp

if (...) else ...switch ...

for (...) ...

do ... while ( )while (...) ...


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Cu trc mt chng trnh Java

Xc lp thng tin mi trng Khai bo lp i tng (Class)

Cc thnh phn (Tokens): nh danh T kha/ t d phng

K t phn cch Hng (Literals) Ton t


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Java Program Structurepublic class MyProgram

{

}

public static void main (String[] args)

{

}

// comments about the class

// comments about the method

method headermethod body


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Chng trnh Java mu

// This is a simple program called Ex1.java// import java.lang.*;class Ex1

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

System.out.println(My first program in Java);

}}


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Bin dch chng trnh java

..\jdk\bin>javac Ex1.java

..\jdk\bin>java Ex1

Ktqu:My first program in Java


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Truyn i s dng lnh

class Ex2{

public static void main(String s[])

{System.out.println(s[0]);System.out.println(s[1]);System.out.println(s[2]);

}}


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Truyn i s trong dng lnh

(Tip theo)


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Chng trnh tnh cn bc hai ca m

import java.io.*;public class canbachai{

public static void Tinhcb2(int m){

double n=0.0;n=Math.sqrt(m);System.out.println("Can bac hai cua " +m+ "la" +n);

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

// tao doi tuong de goicanbachai t=new canbachai();t.Tinhcb2(9);t.Tinhcb2(16);

}}


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Chng trnh tnh n10

import java.io.*;class Tinh_n_mu10{

public static long Tinh(int n){

long tg=1;for(int i=1;i


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Chng trnh kim tra mt s c phi bi ca 5 khng

import java.io.*;public class Boi5

{public static void Kiemtraboi5(int m){

if(m%5!=0)System.out.println(m+"Khong la boi so cua 5");

else System.out.println(m+"La boi cua 5");}public static void main(String[] args){

Boi5 dt1=new Boi5();// tao doi tuong dt1

dt1.Kiemtraboi5(9);Boi5 dt2=new Boi5();// tao doi tuong dt2dt2.Kiemtraboi5(10);

}}


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Chng trnh nhn cc k t g vo t bnphm v ch nhn cc k t s.

class Convert{public static void main (String [] args) throws java.io.IOException {System.out.print ("Please enter a number: ");int num = 0;int ch;

while ((ch = System.in.read ()) != '\n')if (ch >= '0' && ch


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Kiu d liu

Kiu d liu c s (Primitive Data Types)

Kiu d liu tham chiu (Reference data types)

Kiu d liu c s


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Kiu d liu c s 4 kiu integers:

byte, short, int, long 2 kiu s thc:

float, double

1 kiu characters: char

1 kiu boolean :

boolean


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Kiu d liu c s

Type

byte

short

intlong

float

double

Storage

8 bits

16 bits

32 bits64 bits

32 bits

64 bits

Min Value

-128

-32,768

-2,147,483,648< -9 x 1018

+/- 3.4 x 1038 with 7 significant digits

+/- 1.7 x 10308 with 15 significant

digits

Max Value

127

32,767

2,147,483,647> 9 x 1018

Ch t


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57

Characters Character literals are delimited by single

quotes:'a' 'X' '7' '$' ',' '\n'

The ASCII characters :

uppercase letterslowercase lettersPunctuationdigits

special symbolscontrol characters

A, B, C, a, b, c, period, semi-colon, 0, 1, 2,

&, |, \, carriage return, tab, ...

B l


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58

Boolean A boolean value represents a true or

false condition

A boolean can also be used to represent any

two states, such as a light bulb being on oroff

The reserved words true and falseare the only valid values for a boolean type

boolean done = false;


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Kiu d liu tham chiu

Mng (Array)

Lp (Class) Interface


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Cc ton t

Cc loi ton t: Ton tshc (Arithmetic operators)

Ton tdng Bit (Bitwise operators) Ton t so snh (Relational operators)

Ton t logic (Logical operators)

Ton tiukin (Conditional operator) Ton t gn (Assignment operator)


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Ton t s hc

Arithmetic Operators+ Addition (Php cng)

- Subtraction (Php tr)

* Multiplication (Php nhn)

/ Division (Php chia)

% Modulus (Ly s d)

++ Increment (Tng dn)

-- Decrement (Gim dn)


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+= Php cng v gn

-= Php tr v gn

*= Php nhn v gn

/= Php chia v gn

%= Php lysd v gn


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Ton t so snh

(Relational Operators)== So snh bng

!= So snh khc

< Nh hn> Ln hn

= Ln hn hoc bng


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Ton t Bit

(Bitwise Operators)~ Ph nh (NOT)

& V (AND)

| Hoc (OR)

^ Exclusive OR (XOR)

>> Dch sang phi (Shift right)


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Ton t Logic

(Logical Operators )&& Logical AND

|| Logical OR

! Logical unary NOT


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Ton t iu kin

(Conditional Operator) C php

Biuthc 1 ? Biuthc 2 : Biuthc 3;

Biuthc 1

iukinkiu Boolean trv gi tr True hoc False

Biuthc 2

Trv gi trnuktqucamnh 1 l True Biuthc 3

Trv gi trnuktqucamnh 1 l False


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Ton t gn

(Assignment Operator)= Assignment (Php gn)

Gi tr c th c gn cho nhiu bin s

V da = b = c = d = 90;

Th t u tin ca cc ton t


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Th t ca cc ton t c th c thay i bngcch sdng cc dungocn trong mnh

Th t Ton t

1. trong ngoc tnh trc

2. Cc ton t n nh +,-,++,--

3. Cc ton t s hc v cc ton t dchnh *,/,+,-,

4. Cc ton t quan h nh >,=,


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Operator Precedence What is the order of evaluation in the

following expressions?a + b + c + d + e

1 432

a - b / c + d * e

3 241

a / (b + c) - d % e

2 341

a / (b * (c + (d - e)))

4 123

Assignment Revisited


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The assignment operator has a lowerprecedence than the arithmetic operators

First the expression on the right hand

side of the = operator is evaluated

Then the result is stored in the

variable on the left hand side

answer = sum / 4 + MAX * lowest;

14 3 2



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Assignment Revisited The right and left hand sides of an

assignment statement can contain the samevariableFirst, one is added to theoriginal value ofcount

Then the result is stored back into count

(overwriting the original value)

count = count + 1;


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p kiu (Type Casting)

Kiu d liu ny c chuyn i sang mt kiu dliu khcC php: (kiu_mi)biu_thc;

V d : int m=8, n=2;float x1,x2;x1 = m/n; // x1 nhn gi tr l s nguyn;x2 = m/float(n); // x2 nhn gi tr l sthc;

V d :float c = 34.29675;

int b = (int)c + 10;


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Cc k t nh dng xut d liu(Escape Sequences)

Escape

SequenceM t

\n Xung dng mi\r Chuyn con tr n u dng hin hnh

\t Chuyn con tr n v tr dng Tab k tip(k t Tab)

\\ In du\

\ In du nhy n ()

\ In du nhy kp ()


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Hng, Bin, Biu thc

* Hng : Hng l i lng c gi tr khng thay i trong

sut qu trnh thc thi ca chng trnh

* Bin : Bin l i lng c gi tr thay i trong sut qu

trnh thc thi ca chng trnh Khai bo bin chng trnh dnh ring vng

nh thch hp cho bin . Mi lnh truy cp n bin l truy cp n gi trca n.


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Hng, Bin, Biu thc

* Bin:

C php khai bo bin :datatype identifier [=value][, identifier[=value]...];

Khai bo bin s gm 3 thnh phn: Kiu d liu ca bin s

Tn bin Gi tr ban u ca bin (khng bt buc)


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Hng, Bin, Biu thc

* Biu thc :

L mt dy cc ton t v ton hng

+ Ton hng: c th l hng, hm, bin, ...+ Ton t : +, -, *, / , $ , %, & ...

Mi biu thc s c gi tr thuc mt kiud liu no

u tin cao nht cho biu thc con trongcp ngoc n


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Khai bo mng

* Mng mt chiu: datatype identifier [ ];

datatype identifier [ ] = new datatype[size];

datatype identifier [ ]= {value1,value2,.valueN};

* Mng hai chiu :

datatype identifier [ ][ ];

Datatype [ ][ ] identifier;


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Lp v phng thc(Classes & Methods)


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Lp trong Javapublic class MyProgram

{

}

// comments about the class

class header

class body

Comments can be added almost anywhere


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Lp trong Java

C php khai bo lp (Class)

class tnlp

{kiu tnbin;:

met_datatype tnphngthc([dsthams]):}


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Cc lp ni (Nested Classes)

Mt lpcnhngha bn trong mt lpkhc. Lpcgi llpni(Nesting)

Cc kiulpni: Static

Non-static


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Phng thc

(Methods in Classes) Phng thc c nh ngha nh l

mt hnh nghocmt tc vthts

caitng C php

access_specifier modifier datatype method_name(parameter_list)

{

//body of method

}


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V d v s dng phng thcclass Ex3{

int x = 10; // variablepublic void show( )

{ System.out.println(x);

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

Ex3 t = new Ex3( ); // tao doi tuong tt.show( ); // method call

Ex3 t1 = new Ex3( ); // tao doi tuong t1t1.x = 20;t1.show( );

}}


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Cc ch nh truy xut ca phng

thc (Access specifiers) Cng cng (public)

Ring t (private)

Bo v (protected)


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Nhng phng thc c np chng :(Methods Overloading)

Nhng phng thc c np chng : Cng trong mt lp

C cng tn Khc nhau v danh sch tham s

Nhngphngthcc npchng l

mt hnh thc a hnh trong qu trnhbin dch (compile time)


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Ph th khi t


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Phng thc khi to

(Class Constructors) L mtphng thccbit dng khito gi tr cho cc bin thnh vin ca lpitng

C cng tn vi tn lp v khng c gi trtrv

cgi khi itngcto ra C 2 loi:

Tng minh (Explicit constructors) Ngmnh (Implicit constructors)


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Phng thc khi to ca lp dn xut(Derived class constructors)

C cng tn vi lp dn xut (subclass)

Nu lp dn xut mun gi hm

constructor ca lpcs th cu lnhgi hm constructor calpcsphil cu lnh u tin trong hm

constructor calpdnxut Dng t kho super


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Cc lnh iu khin

iu khin r nhnh:

Mnhif-else

Mnhswitch-case

Vng lp (Loops):

Vng lpwhile

Vng lpdo-while

Vng lpfor


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Lnhswitch-case

C phpswitch (expression)

{

case 'value1': action1 statement(s);

break;

case 'value2': action2 statement(s);

break;

:

:case 'valueN': actionN statement(s);

break;

default: default_action statement(s);

}


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Lnh lp do-while

C php

do

{action statements;:

:}while(condition);


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Vng lp for

C php

for(initialization statements ; condition ; increment statements)

{

action statements;

:

:

}


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Chng 3

Gi & Interface

(Packages & Interfaces)


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Gii thiu Nhng thnh phn c bn ca chng trnh Java:

Gi (Packages)

Giao din (Interfaces)

Nhng phn ca mt chng trnh Java:

Lnh khai bo gi(package )

Lnhchnh gi c dng (Lnh import)

Khai bo lp public (mt file java chcha 1 lp public

class) Cc lp khc (classes private to the package)

Tp tin ngun Java c thchattchocmtvi trong s cc phn trn.


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Interfaces

Interface chnh l lp abstract thun tu

Khai bo nhng phng thc m lp s dng

Trong Java 1 lp ch c th dn xut t 1 lpduy nht ti cng mt thi im, nhng cth dn xut cng lc nhiu Interface

Trong Interface khng cha nhng phng

thc c th (concrete methods) interface cn phi c implements.


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Cc bc to interface

nh ngha Interface Bin dch Interface

Implements Interface

Tnh cht ca interface:

Ttcphngthc trong interface phi lpublic. Cc phng thc phi c nh ngha

trong lpdnxut interface .


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Nhng lu khi to gi:


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Nhnglu khi to gi: M ngun phibtubnglnh package

M ngunphinm trong cng thmc mang tnca gi

Tn gi nn btubng k tthng (lower case) phn bitgia tn lpitng v tn gi

Nhng lnh khc phivit pha di dng khai bogi l mnh import, k n l cc lnh nhnghalpitng

Nhng lpi tng trong gi cnphic bin

dch. chng trnh Java c th s dng nhng gi

ny, ta phiimport gi vo trong m ngun


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Import gi (Importing packages):

C 2 cch:

Xc nh lp hoc interface ca gi cnc import.

- Hoc c th import ton b gi

vd : import java.util.Vector;import java.util.*;

Cc bc to ra gi


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Cc bc to ra gi

(Package) Khai bo gi Import nhng gi chun cn thit

Khai bo v nh ngha cc lp itng c trong gi

Lu thnh tp tin .java, v bin dch

nhng lp i tng c nhngha trong gi.

S d h i d i d h


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S dng nhng gi do ngi dng nhngha (user-defined packages)

M nguncanhngchng trnh ny phicng th mc ca gi do ngi dng nhngha. Nu khng ta phithitlpngdn.

nhng chng trnh Java khc s dngnhng gi ny, import gi vo trong m ngun

Import nhnglpitngcn dng

Import ton b gi To tham chiunnhng thnh vin ca gi


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Thit lp ng dn - xc lp CLASSPATH

L danh sch cc th mc, gip chovic tm kim cc tp tin lpitng

tngng Nn xc lp CLASSPATH trong lc

thc thi (runtime), v nhvy n s xc

lp ng dn cho qu trnh thc thihin hnh

Gi v iu khin truy xut


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Gi v iu khin truy xut(Packages & Access Control)


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Gi java.lang

Gi java.lang c import mc nh.

Nhng lp Wrapper cho cc kiu dliu nguyn thy:


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Lp String

Phng thc khi to (Constructor): String str1 = new String();

String str2 = new String(HelloWorld); char ch[ ] = {A,B,C,D,E};

String str3 = new String(ch);

String str4 = new String(ch,0,2);


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String Pool

String Pool i din cho tt c cc kt c to ra trong chng trnh

Khi nimString Pool

S


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Nhng phng thc ca lp String

charAt( )// startsWith() endsWith( )

copyValueOf( ) toCharArray( ) indexOf( ) toUpperCase( )

toLowerCase( ) trim( ) equals( )


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Lp java.lang.Math

abs()

ceil()// lam tron tren

floor()// lam tron duoi max()

min()

round()

random()

sqrt()

sin() cos()

tan()


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Lp Runtime

ng gi (Encapsulates) mi trngthc thi Dng qun l bnh, v thi hnh nhng

tin trnh cng thm

Phngthc: exit(int) freeMemory( ) getRuntime( )

gc( ) totalMemory( ) exec(String)

Lp System


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Cung cpnhnglungchunnhnhp (Input), xut(Output) v cc lungli(ErrorStreams)

Cung cpkhnng truy xutnnhng thuc tnhcahthngthc thi Java, v nhngthuc tnh mitrngnh phin bn,ngdn, nh cung cp

Phngthc:

exit(int)

gc()

getProperties()

setProperties() currentTimeMillis()

arraCopy(Object, int, Object, int, int)


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L Obj


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Lp Object

L lp cha ti cao ca tt c cc lp Phng thc:

equals(Object) finalize()

notify()

notifyAll()

toString() wait()

i


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Gi java.util

Cung cp phn ln nhng lp Javahu dng v thng xuyn cn ntrong hu ht cc ng dng

Giithiunhnglptrutng sau: Hashtable

Random

Vector StringTokenizer


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Nhng phng thc ca lp


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Nhng phng thc ca lpHashtable

clear()

done()

contains(Object) containsKey(Object)

elements()

get(Object key)

isEmpty()

keys()

put(Object, Object)

rehash() remove(Objectkey)

size()

toString()


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Nhng phng thc ca lp


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Nhng phng thc ca lpRandom

nextDouble()

nextFloat()

nextGaussian() nextInt()

nextLong()

setSeed(long)

L V t


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Lp Vector

Cung cp kh nng co gin cho mng khithm phnt vo mng

Lutrnhng thnh phncakiu Object

Mt Vector ring r c th lu tr nhngphnt khc nhau, l nhng instance canhnglp khc nhau

Phngthckhito (Constructors): Vector(int) Vector(int, int) Vector()

Nhng phng thc ca lp


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Nhng phng thc ca lpVector

addElement(Object) capacity( ) clone( ) contains(Object) copyInto(Object [ ]) elementAt(int) elements( ) ensureCapacity(int) firstElement( )

indexOf(Object) indexOf(Object, int) insertElementAt(Object,

int)

isEmpty( ) lastElement( ) lastIndexOf(Object) lastIndexOf(Object, int) removeAllElements( )

removeElement(Object) removeElementAt(int) setElementAt(Object,

int)

setSize(int) size( ) toString( ) trimToSize( )

L St i T k i


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Lp StringTokenizer

C thc dng tch mtchui thnh nhngthnh phncu thnh ca n (constituent tokens)

K t phn cch c th c ch nh khi mt i

tngStringTokenizerckhito Phngthckhito (Constructors):

StringTokenizer(String)

StringTokenizer(String, String)

StringTokenizer(String, String, Boolean) Lp StringTokenizer s dng giao din lit k

(enumeration interface)

Nhng phng thc ca lp


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g p g t c ca pStringTokenizer

countTokens( )

hasMoreElements( )

hasMoreTokens( ) nextElement( )

nextToken( )

nextToken(String)


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Chng 4

X l bit l

Gii thi bit l


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Gii thiu v bit l

L mtkiulicbit N xy ra trong thi gian thc thi on

lnh Thng thng cc iu kin thc thi

chng trnh gy ra bitl Nu cc iukin ny khng cx

l, th vic thc thi c thkt thc tngt


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X l bit l


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X l bit l

Khi mtbitlxy ra, itngtngngvibitlscto ra.

itng ny sau ctruyntiphngthc

ni m bitlxy ra. itng ny cha cc thng tin chi titvbitl.

Thng tin ny c thnhnc v x l.

Lp throwable m Java cung cp l lp trn nht

calpbitl.


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Cu trc ca m hnh x l bit l


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Cu trc ca m hnh x l bit l

C phptry { . }catch(Exception e1) { . }catch(Exception e2) { . }catch(Exception eN) { . }finally { . }

M hnh Catch and Throw nng cao


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M hnh Catch and Throw nng cao

Ngi lp trnh ch quan tm ti cc likhi cnthit.

Mt thng bo li c thc cung cptrong exception-handler.

Khi try v catch


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Khi try v catch

csdng thchin trong mhnh catch and throwcax l bitl.

Khi lnh try gm tp hp cc lnhthc thi

Mthocnhiukhilnhcatch c thtip theo sau mtkhilnhtry

Cc khi lnh catch ny bt bit ltrong khilnhtry.

Khi lnh try v catch (tt)


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Khi lnh try v catch (tt)

btbtkloibitl no, ta c thch rakiubitl l Exceptioncatch(Exception e)

Khi bit lb bt khng bit thuckiu no,chng ta c th s dng lp Exception btbitl.

Li s c truyn thng qua khi lnh try

catch cho ti khi chng bt gp mt catchtham chiuti n, nu khng chng trnh sbkt thc


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Khi lnh cha nhiu Catch


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(tt) Khi s dng cc try lng nhau, khi try

bn trong cthc thi trc. Bt k bit l no b chn trong khi lnh

try s b bt trong khi lnh catch tipngay sau. Nukhilnhcatch thch hp khng c

tm thy, th cc khi catch ca khi try

bn ngoi sc xem xt Ngcli, Java Runtime Environment sx

l bitl.


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Danh sch cc bit l (tt)


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Danh sch cc bit l (tt)

NumberFormatException

AWTException

IOException FileNotFoundException

EOFException

NoSuchMethodException InterruptedException


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AWT bao gm cc lp interfaces v cc gi


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AWT bao gm cc lp, interfaces v cc gikhc

Components


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Components

Ttc cc thnh phncu to nn chngtrnh GUI cgi l component.

VdContainers,

textfields, labels, checkboxes, textareas

scrollbars, scrollpanes, dialog


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Panels


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Panels

L cc vng cha trong mtcas.

Hin th trong mt ca s m trnh duythoc appletviewer cung cp v khng cngvin.

c s dng nhm mt s cc thnhphn

Mt panel khng th nhn thy v th chngta cnphi thm n vo frame.


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Cc Components khc


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Cc Components khc

Vd

textfields, labels, checkboxes, textareas

scrollbars, scrollpanes, dialog

Label


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Label

c dng hin th chui (String) Cc hm todng:

Label( )

Label(String labeltext) Label(String labeltext, int alignment)

Cc phng thc: setFont(Font f)

setText(String s) getText( )

TextField

L iu khin text cho php hin th text hoc


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L iukhin text, cho php hinth text hoc

cho user nhpdliu vo. Cc hm dng: TextField( )

TextField(int columns)

TextField(String s) TextField(String s, int columns)

Cc phngthc: setEchoChar(char) setText(String s)

getText( )

setEditable(boolean)

isEditable( )


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TextArea (tt)


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TextArea (tt)

Cc hm dng: TextArea( )

TextArea(int rows, int cols )

TextArea(String text)

TextArea(String text, int rows, int cols)


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Button


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Button

Cc nt n l cch dnht ly ccskincangi dng.

Cc hm todng: Button( )

Button(String text)


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FlowLayout


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FlowLayout l layout manager mcnh chocc applet v cc panel

Vi FlowLayout cc component s c

spxpt gc tri trn n gc phidica mn hnh theo tng hng. Cc constructor:

FlowLayout mylayout = new FlowLayout();FlowLayout exLayout = newflowLayout(FlowLayout.RIGHT);

BorderLayout BorderLayout mc nh cho Window,

F Di l


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Frame v Dialog

Trnh qun l ny c thb tr containerthnh 5 vng, NORTH, EAST, SOUTH,WEST v CENTER.

V d: thm mt thnh phn vovng North ca containerButton b1= new Button(NorthButton);

setLayout(new BorderLayout( ));add(b1, BorderLayout.NORTH);

CardLayout


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y

C th lu tr mt danh sch cc kiulayout khc nhau

Mi layout c xem nhmtth (card)

Ththng l itng Panel Mt thnh phnc lpnh button siukhin cc th ct pha trn nht

Cc bcto CardLayout: B tr layout ca panel chnh l CardLayout Lnlt thm cc panel khc vo panel chnh


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GridBagLayout


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B tr cc thnh phn mt cch chnhxc Cc thnh phn khng cn c cng kch

thc Cc thnh phncspxp trong mt

licha cc dng v cc ct Th t t cc thnh phn khng tun

theo hng t tri-sang-phi v trn-xung-di Hm constructor

GridBagLayout gb = new GridBagLayout( );


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LpGridLayout


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Lp GridLayout cung cp cc hm to lp sp hng cc thnh phn giao

din:GridLayout()

GridLayout(int rows, int columns)

GridLayout(int rows, int columns, int hoiongap, int verticalgap)

To ra mt li hnh chnht c rows columns c khong cch gia cchng cc ct lhorizongap, verticalgap. Mt trong hai isrowshoccolumnsc th l 0, nhng khng thc hai, GridLayout(1,0) l to ra li c mt hng.


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//To ra li hnh chnht c 4 v tlayout spxp cc thnh phn //xLabel, xInput, yLabel, yInput


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, p , y , y p

setLayout(new GridLayout(2,2));

add(xLabel); //t xLabel vo thnht

add(xInput); //t xInput vo thhai

add(yLabel); //t yLabel vo thba

add(yInput); //t yInput vo tht

}

}


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Scrollbar sb1=new Scrollbar(Scrollbar.VERTICAL,0,10,-50,100);

Scrollbar sb2=new Scrollbar(Scrollbar VERTICAL 0 10 50 100);


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Scrollbar sb2=new Scrollbar(Scrollbar.VERTICAL,0,10,-50,100);

setLayout(new BorderLayout());

add(nutVe, BorderLayout.NORTH);//tnutVe trn (NORT)

add(msg, BorderLayout.SOUTH); //tmsg di (SOUTH)

add(vungVe,BorderLayout.CENTER);//tvungVe gia (CENTER)

add(sb1, BorderLayout.WEST); //tsb1 bn tri (WEST)

add(sb2, BorderLayout.EAST); //tsb2 bn phi (EAST)

}

}


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X l cc s kin


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Cc bccn tun thsdng m hnhEvent Listener:

Ci t Listener tngng

Nhn din c tt c cc thnh phn to skin

Nhndincttc cc skincx l

Ci t cc phngthcca listener, v vit cc

on m x l skin trong cc phngthc

Interface nh ngha cc phng thc khcnhau x l miskin


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c/ItemEventCc thnh phnca GUI gy ra cc skinv cc mcgm c:

Ch kb khi t thi h ki t Ch kb th i


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Checkbox - khi trng thi cahpkim tra Checkbox thay i

CheckboxMenuItem - khi trng thi cahpkim tra Checkbox ngvimccathcn thay i,Choice - khi mtmc trong danh sch cchnhocbloibList - khi mtmc trong danh sch cchnhocbloib.

LpItemEvent c hm:Object getItem()

Cho liitngcchn hay vabloib.d/ TextEventCc thnh phnca GUI gy ra cc skinvtextgm c:

TextArea - khi kt thc bngnhn nt ENTER,TextField - khi kt thc bngnhn nt ENTER.

Kiuskin Ngun gy ra

s kinCc hm n nhn v di

di cc s kinGiao din Listener tng

ng


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AcitionEvent

AdjustmentEvent

ItemEvent

TextEvent

ButtonListTextFieldScrollbar

ChoiceCheckboxCheckboxMen

uItemListTextAreaTexField

addComponentlistener

remove ActiontListener

addAdjustmentListenerremoveAdjustmentListener

addItemListenerremoveItemListener

addTexListener

removeTextListener

AcitionListener

AdjustmentListener

ItemListener

TextListener

2. Cc s kin mc thpa/ ComponentEvent

Skin ny xuthin khi mt thnh phnb che giu,hinth hay thay ili kch thc Lp ComponentEvent c hm:


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li kch thc. LpComponentEvent c hm:

Component getComponent()Cho liitng tham chiukiuComponent.b/ ContainerEvent

Skin ny xuthin khi mt thnh phncb sung hay bloibkhiphntcha (Container).

c/ FocusEvent

Skin ny xuthin khi mt thnh phnnhncmt nt tbn phm.d/ KeyEventLpKeyEvent l lp con calptrutngInputEvent csdngxl cc skin lin quan n cc phm ca bn phm.

int getKeyCode()i vi cc s kin KEY_PRESSED hoc KEY_RELEASED, hm ny

csdngnhnli gi tr nguyn tngngvi m ca phm trnbn phm.

char getKeyChar()ivi cc skin KEY_PRESSED, hm ny csdngnhnli gitr nguyn, m Unicodetngngvi k tca bn phm.


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Vd: Xy dngngdng c giao dinha GUI


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import java.awt.*;import java.awt.event.*;import java.applet.*;interface IGeometryConstants { // nh ngha Interface gm cc hng cho

t


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192

trc

int SQUARE = 0;int CIRCLE = 1;int ELLIPSE = 2;String[] shapeNames = {"Square", "Circle" , "Ellipse"};int SMALL = 0;int MEDIUM = 1;int LARGE = 2;String[] sizeNames = {"Small", "Medium" , "Large"};

}public class DemoApplet extends Applet implements

IGeometryConstants {// Khai bo mtPanelcha cc Checkboxtngngvi cc loi hnh shapePanel shapePanel;// Khai bo mtPanelCheckboxGroup shapeCBG; // Khai bo mtCheckboxGroupCheckbox squareCB; // Khai bo mtCheckboxngvi hnh vungCheckbox circleCB; // Khai bo mtCheckboxngvi hnh trnCheckbox ellipseCB; // Khai bo mtCheckboxngvi hnh ellipse// Khai bo mtPanelcha cc Labelv cc TextFieldPanel xyPanel; // Khai bo mt Panel xyPanelLabel xLabel; // Khai bo mt Label xLabelTextField xInput; // Khai bo mt TextField xInputLabel yLabel; // Khai bo mt Label yLabel

TextField In ut; // Khai bo t TextField In ut

// Khai bo mtPanelcha cc Label, Choice v CheckboxPanel sizePanel;Label sizeLabel;Ch i i Ch i


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Choice sizeChoices;

Checkbox fillCB;// Khai bo mtPanel chashape, coordinates, size and fill Panel leftPanelPanel leftPanel;// Khai bo mtPanel chaMassage display, draw button and canvasPanel rightPanel;Button drawButton;DrawRegion drawRegion;TextField messageDisplay;

// nhnghali hm init()public void init() {

makeShapePanel();makeXYPanel();makeSizePanel();makeLeftPanel();makeRightPanel();

// Gi hm x l cc skinaddListeners();//a cc Panelvo hthngadd(leftPanel);add(rightPanel);

}

// a cc thnh phnv cc shapevo shapePanelvoid makeShapePanel() {shapePanel = new Panel();


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p ();shapeCBG = new CheckboxGroup();

squareCB = new Checkbox(shapeNames[SQUARE], shapeCBG, true);circleCB = new Checkbox(shapeNames[CIRCLE], shapeCBG, false);ellipseCB = new Checkbox(shapeNames[ELLIPSE], shapeCBG, false);shapePanel.setLayout(new FlowLayout());shapePanel.add(squareCB);shapePanel.add(circleCB);shapePanel.add(ellipseCB);

}//a cc thnh phnv cc x,y coordinatesvo xyPanelvoid makeXYPanel() {

xyPanel = new Panel();xLabel = new Label("X Coordinate:");yLabel = new Label("Y Coordinate:");xInput = new TextField(5);yInput = new TextField(5);xyPanel.setLayout(new GridLayout(2,2));xyPanel.add(xLabel);xyPanel.add(xInput);xyPanel.add(yLabel);xyPanel.add(yInput);

}

//a cc thnh phnvsizevfillvo sizePanelvoid makeSizePanel() {

sizePanel = new Panel();


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sizeLabel = new Label("Size:");

sizeChoices = new Choice();sizeChoices.add(sizeNames[0]);sizeChoices.add(sizeNames[1]);sizeChoices.add(sizeNames[2]);fillCB = new Checkbox("Fill", false);sizePanel.setLayout(new FlowLayout());

sizePanel.add(sizeLabel);sizePanel.add(sizeChoices);sizePanel.add(fillCB);

}//a cc thnh phn vo leftPanelvoid makeLeftPanel(){

leftPanel = new Panel();

leftPanel.setLayout(new BorderLayout());leftPanel.add(shapePanel, "North");leftPanel.add(xyPanel, "Center");leftPanel.add(sizePanel, "South");}

//a cc thnh phn vo rightPanelvoid makeRightPanel(){

rightPanel = new Panel();


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rightPanel new Panel();

messageDisplay = new TextField("MESSAGE DISPLAY");messageDisplay.setEditable(false);messageDisplay.setBackground(Color.yellow);

drawButton = new Button("Draw");drawButton.setBackground(Color.lightGray);

drawRegion = new DrawRegion();drawRegion.setSize(150, 150);drawRegion.setBackground(Color.white); rightPanel.setLayout(new BorderLayout());rightPanel.add(drawButton, BorderLayout.NORTH);

rightPanel.add(messageDisplay, BorderLayout.SOUTH);rightPanel.add(drawRegion, BorderLayout.CENTER);}

// X l cc skintngngvi cc victhchin trn cc thnh phnhavoid addListeners(){

drawButton addActionListener(new ActionListener(){


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drawButton.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent evt){int shape, xCoord, yCoord, width;messageDisplay.setText("");if(squareCB.getState())

shape = SQUARE;else if (circleCB.getState())

shape = CIRCLE;else if (ellipseCB.getState())

shape = ELLIPSE;else {messageDisplay.setText("Unknow shape");return;

}try{

xCoord = Integer.parseInt(xInput.getText());

yCoord = Integer.parseInt(yInput.getText());}catch(NumberFormatException e){messageDisplay.setText("Illegal coordinate");

return;}

switch(sizeChoices.getSelectedIndex()){

case SMALL: width = 30; break;case MEDIUM: width = 60; break;case LARGE: width = 120; break;


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198

default:

messageDisplay.setText("Unknow size");return;

}

messageDisplay.setText("Drawing..."+shapeNames[shape]);

drawRegion.doDraw(shape,xCoord,yCoord, fillCB.getState(),width);}

});xInput.addTextListener(new TextListener(){

public void textValueChanged(TextEvent evt){checkTF(xInput);

}});yInput.addTextListener(new TextListener(){

public void textValueChanged(TextEvent evt){checkTF(yInput);

}});

}// Kt thc hm addListener()

void checkTF(TextField tf){

messageDisplay.setText("");try{

Integer.parseInt(tf.getText());


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Integer.parseInt(tf.getText());}catch(NumberFormatException e){messageDisplay.setText("Illegal coordinate ");

}}

}//nhnghalpDrawRegion mrnglpCanvasvsdng cc hng giaodinclass DrawRegion extends Canvas implements IGeometryConstants{private int shape,xCoord, yCoord;

private boolean fillFlag;private int width;public DrawRegion(){

setSize(150, 150);setBackground(Color.white);}

//nhngha hm doDraw() v

public void doDraw(int h, int x, int y, boolean f, int w){this.shape = h;this.xCoord = x;this.yCoord = y;this.fillFlag = f;this.width = w;repaint();

}

public void paint(Graphics g){

switch(shape){case SQUARE:


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if(fillFlag) g.fillRect(xCoord, yCoord, width,width);else g.drawRect(xCoord, yCoord, width,width);

break;case CIRCLE:if(fillFlag) g.fillOval(xCoord, yCoord, width,width);else g.drawOval(xCoord, yCoord, width,width);

break;case ELLIPSE:if(fillFlag) g.fillOval(xCoord,yCoord,width,width/2);else g.drawOval(xCoord, yCoord, width,width/2);

break;}

}}

Menus


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Cc loi menu : Pull-down

Pop-up menu

Ch c tht cc thanh menubar votrong cc Frame m thi

Cc thnh phnca menu:

Menubar MenuItems

Thnh phnMenuLpabstract class MenuComponent l lpcscho ttc cc lpthchinnhngvn lin quan nthcn (menu).

LpMenuBarci t thanh thcn v trong c thcha cc thcn pull-down.LpMenuItem nhnghatngmccathcn.


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202

p g g

LpMenu ci t cc thcnpull-down c tha vo mtthcnbtk.LpPopUpMenu biudin cho thcn pop-up .LpCheckboxMenuItem cha cc mccchnkim tra trong cc mc.Victolpmt thanh thcn cho mtframe cthchinnhsau:1. To ra mtthanh thcn,MenuBar thanhThDon = new MenuBar();

2. To ra mtthcn,Menu thucDon = new Menu(Cac loai banh);

3. To ra cc mc trong thcn v a vo thcn,MenuItem muc = new MenuItem(Banh day);thucDon.add(muc); //amucvo thucDon

4. a cc thcn vo thanh thcn,thanhThDon.add(thucDon); //athucDonvo thanhThDon

5. To ra mtframe v a thanh thcn vo frame .Frame frame = new Frame(Cac mon an);frame.add(thanhThDon); //athanhThDonvo frame

Thnh phnMenuVd: Tolp v sdng cc thcn.import java.awt.*;

import java.applet.*;


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public class MenuDemo extends Applet{public static void main(String args[]){

MenuBar thanhThDon = new MenuBar();

Menu thucDon = new Menu("Cac loai banh");

MenuItem b1 = new MenuItem("Banh day");

thucDon.add(b1);

MenuItem b3 = new MenuItem("Banh khoai");

thucDon.add(b3);

thucDon.addSeparator();// To ra mt thanh phn cchMenuItem b4 = new MenuItem("Banh gio");

thucDon.add(b4);

thucDon.add(new CheckboxMenuItem("Banh ran"));thanhThDon.add(thucDon);

Frame frame = new Frame("Cac mon an");

frame.setMenuBar(thanhThDon);

frame.pack();frame.setVisible(true);}

}


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Chng VI

Applets


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Cu trc applet


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nhnghamt applet tbnskinxy ratrong qu trnh thc thi

ivimiskincnhnghabimt

phngthctngng. Cc phngthc: init( ) start( )

stop( ) destroy( )

Cc phngthc khc:


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paint( ) repaint( )

showStatus( )

getAppletInfo( )

Cc phng thc init(), start(), stop(),destroy(), and paint() cthakt applet.

Mi phng thc ny mc nh l rng. V

th cc phng thc ny phi c npchng.

Bin dch v thc thi applet


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Mt applet th c bin dch theo c phpsau

javac Applet1.java

thc thi mt applet, tomttp tin HTMLc sdngth applet Th applet c hai thuc tnh:

Width Height

truyn tham s ti applet, s dng thparam, v tip theo l thvalue

Applet c th c thc thi bng appletviewer

im khc bit gia applet v mt ng dng Cc ngdng khi thc thi phisdng trnh

bin dch Java, trong khi cc applets thc thic trn bt k trnh duyt no m h tr


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c trn btk trnh duyt no m h trJava, hoc s dng AppletViewer trongJDK.

Mt ng dng bt u vi phng thcmain(). Cn i vi applet th khng sdngphngthc ny

MtngdngsdngSystem.out.println()hinth, trong khi mt applet th sdngcc phngthccalp Graphics.

Nhng hn ch v bo mttrong applet


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g pp Khng thchocvit cc tp tin trn h

thngtp tin cangisdng

Khng th giao tipvimt site trn internet.

M ch giao tip vi mt dch v trn trangweb c applet.

Khng thchybtkchng trnh no trnhthngcangic

Khng th load bt k chng trnh noclu trn hthngcangisdng

Chu trnh sng ca applet


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Truyn tham s ti mt applet


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truyn tham s, s dng PARAMtrong th HTML

V d

Lp ha


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c cung cpbi gi AWT

Cung cpmttphp cc phngthcvnh sau:

Oval Rectangle

Square

Circle

Lines

Text in different fonts

Graphical Background


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Cc phngthcvnn : getGraphics( )

repaint( )

update(Graphics g)

paint(Graphics g)

Hin th chui, k t v bytes Phng thcvhochin thmt chui

trn frame


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C php drawString(String str, int xCoor, int yCoor);

Phng thcvhochin th cc k ttrn frame

C php drawChars(char array[ ], int offset, int length, int xCoor, int yCoor);

Phng thcvhochin th bytes trnframe

C php drawBytes(byte array[ ], int offset, int length, int xCoor, int yCoor);

V cc hnh th Phng thc c s dng v

ngthngnh sau


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C php drawLine(int x1, int y1, int x2, int y2);

Cc phng thccsdngv

ng trn nh sauC php drawOval(int xCoor, int yCoor, int width, int height);

setColor(Color c);

fillOval(int xCoor, int yCoor, int width, int height);

Phng thc s dng v hnhvung:

C php


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C php drawRect(int xCoor, int yCoor, int width, int

height);

fillRect(int xCoor, int yCoor, int width, intheight);

Cc phng thc c s dng v hnh vung c gc trn

C php drawRoundRect(int xCoor, int yCoor, int width, int height, intarcWidth, int arcHeight);

fillRoundRect (int xCoor, int yCoor, int width, int height, intarcWidth, int arcHeight);

3D Rectangles & Arcs


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Cc phng thccsdngvhnh 3D C php

draw3DRect(int xCoord, int yCoord, int

width, int height, boolean raised);

drawArc(int xCoord, int yCoord, int width,int height, int arcwidth, int archeight);

fillArc(int xCoord, int yCoord, int width, intheight, int arcwidth, int archeight);

Drawing PolyLines


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Cc phng thc c s dng vnhiu onthngC php

drawPolyline(int xArray[ ], int yArray[ ], inttotalPoints);

g.setFont(new Font("Times Roman",

Font.BOLD,15));

V v t cc hnh a gic


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Cc phng thc v v t cc hnh a gic

C php

drawPolygon(int x[ ], int y[ ], intnumPoints);

fillPolygon(int x[ ], int y[ ], int numPoints);

Mu


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Java sdng mu RGB

Bng cc gi tr mu

Element RangeRed 0-255

Green 0-255

Blue 0-255 C php ca hm dngtomt mu

color(int red, int green, int blue);

Bng trnh by cc gi tr mu RGB thng thng

Color Red Green Blue


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White 255 255 255Light Gray 192 192 192

Gray 128 128 128

Dark Gray 64 64 64

Black 0 0 0

Pink 255 175 175

Orange 255 200 0

Yellow 255 255 0Magenta 255 0 255

Font


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Gi java.awt package cung cp bi lpFont

Cc phng thc ca lp Font: getAllFont( )

getLocalGraphicsEnvironment( )

getFont( )

getFontList( )

Hm dng Font nhn 3 tham s Tn font trong chui nhdng; tn ny c


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g g; ytrong phngthc getFontList( ).

Kiuca font.

V d : Font.BOLD, Font.PLAIN, Font.ITALIC

Kch thcca font. V d

Font f1 = new Font("SansSerif", Font.ITALIC, 16);

g.setFont(f1);

Lp FontMetrics


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o cc k t khc nhau hin th trongcc font khc nhau.

Vic o bao gm height, baseline,

ascent,descent v leadingca font. N khng c th v n l mt lp tru

tng

Lp FontMetrics (tip theo)


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Phng thc: getFontMetrics(f1)

getHeight( )

getAscent( ) getDescent( )

getLeading( )

getName( )


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Chng VII

Lp trnh a tuyn

anhim,tin trnh v lung

Lp trnh a tuyn


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Xl alung trong JavaMcu tin calung

Vn ng b ho v bi ton tc

nghn

Tin trnh, a nhim va lung Tin trnh : l mt chng trnh chy trn h iu

hnh v cqun l thng qua cc th


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Tiu trnh : l mtnvx l cbncahthng.Mttin trnh shunhiutiu trnh

nnhim : timtthiimch c mttin trnh

anhim: cng mt thiim c nhiuhnmttin trnh thc hin ng thi trn cng mt mytnh. C hai kthutanhim:

+ anhimda trn cc tin trnh+ anhimda trn cclung

Tin trnh, a nhim va lung Mt tin trnh c th bao gm nhiu lung.

Cc lungcamttin trnh c thchiasvi


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gnhau vkhng gian achchngtrnh, ccon d liu v mi trngx l, ng thicngc vng dliu ring thao tc.

Trong mi trngnlung,mithiimch cho php mt tc vthc thi.

K thut a nhim cho php tn dng cnhng thi gian ri ca CPU thc hinnhng tc v khc.

anhim c ththchinc theo hai cch:+ Phthuc vo hiu hnh, n c th cho


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tm ngng chng trnh m khng cn thamkho cc chng trnh .

+ Cc chng trnh chbdngli khi chng

tnguynnhngiukhin cho chng trnhkhc. Nhiuhiu hnh hin nay htralung,

Java h tr a nhim da trn cc lung vcung cp cc c tnh mc cao cho lp trnhalung.

a lung (a tuyn)


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L khnng lm vicvinhiulung

a lung chuyn s dng cho victhc thi nhiu cng vicngthi

a lung gim thi gian ri ca hthngnmcthpnht.

To v qun l lung Khi chng trnh Java thc thi hm


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main() tc l lung main cthc thi.Tuyn ny c to ra mt cch tng,tiy :

- Cc lung con scto ra t

- N l lungcui cng kt thc victhcthi. Ngay khi lung main() ngngthc thi,chng trnh bchmdt

Phn chia thi gian gia cc lung


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CPU thc thi chmtlungtimtthiimnhtnh.

Cc lung c u tin bng nhau th

c phn chia thi gian sdngb vix l.

Lp trnh a lung Java Vi Java ta c th xy dng cc chng trnh a

lung


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Mt ng dng c th bao gm nhiu lung,milungcgn cng viccth v cthc thingthivi cc lung khc

Java cung cp hai gii php tolplung:1. Thitlplp con ca Thread2. Ci tlpxl lungtgiao din Runnable.

Lp trnh a lung Java Cch thnht: To ra mtlpkthatlp Thread v ghi

phngthc run calp Thread nhsau:class MyClass extends Thread


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{//Mtsthuc tnhpublic void run()

{// Cc lnhcnthchin theo lung}

//Mts hm khc cvit hay cb sung}

Khi chng trnh chy n s gi mt hm c bit c

khai bo trong Thread l start()btumt lungcto ra.

Lp trnh a lung JavaCch thhai:

+ Java giiquythnch trnbng cch xy dnglpto racc lungthchin trn csci t giao dinhtrlung.


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+ To ra mt lp trin khai t giao din Runnable, ci tphngthc runclass MyClass implements Runnable

{

// Cc thuc tnh//Npchng hay vitmts hmpublic void run()

{

. . .

}}

Trng thi v cc phng thcca lp Thread


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Trng thi: born

ready to run

running

sleeping

waiting

ready

blocked dead

Phng thc: start( )

sleep( )

wait( ) notify( )

run( )

stop( )

Cc trng thi ca ThreadMtlung c thmt trong cc trng thi sau:

+ New: Khi mt lung mi c to ra vi ton tnew()v sn sng hotng.


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g+ Runnable: Trng thi m lungangchim CPU

thc hin, khi bt u th n gi hm start(). B lp lchphn lung ca h iu hnh s quyt nh lung no scchuynvtrng thi Runnablev hotng.Cngcn

lu rngmtthiim,mtlungtrng thi Runnablec thhoc khng ththchin.+ Non runnable (blocked): T trng thi runnable

chuyn sang trng thi ngngthchin(bchn) khi gi

mt trong cc hm: sleep(),

suspend(),

wait(), hay

bchn

liInput/output. Trong trng thibchn c ba trng thicon:

yield

sleep


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Blocked

stop

B chn bi I/O

resume

suspendstart

Runnablenotify

wait

Kt thc I/O

Cc trng thi ca ThreadMtlung c thmt trong cc trng thi sau:

+ Waiting: khi trng thi Runnable, mt


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lung thc hin hm wait() th n s chuyn sangtrng thi chi (Waiting).

+ Sleeping: khi trng thi Runnable, mt

lung thchin hm sleep() th n schuyn sangtrng thi ng (Sleeping).

+ Blocked: khi trng thi Runnable, mtlungbchnlibinhng yu cuv ti nguyn,

nh yu cu vo/ra (I/O), th n s chuyn sangtrngbchn (Blocked).

Cc trng thi ca ThreadMi lungphi thot ra khi trng thi Blocked quay vtrng thi Runnable, khi

+ Nu mt lung c cho i ng (sleep) sau


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khong thi gian bng s micro giy n c truyn votham sca hm sleep(n).

+ Numtlungbchnli v vo/ra v qu trnh nykt thc.

+Nulungbchnli khi gi hm wait(), sau cthng bo tiptcbng cch gi hm notify() hoc notifyAll().+ Nu mt lungb chn li ch monitor ca i

tngangbchimgibilung khc, khi monitor cgii phng th lungbchn ny c thtiptcthchin (khi

nim monitor ccpphn sau).

Cc trng thi ca Thread+Numtlungbchnlibiligi hm suspend(),

munthchin th trcphigi hm resume().


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+ Hm suspend() c tc dngtmngngtuyn, t cdng do khng nh ti nguyn ca h thng, d dn ndeaklock.

Nu ta gi cc hm khng ph hpivi cc lung th JVMs pht sinh ra ngoil IllegalThreadStateException.

+ Dead: Lungchuyn sang trng thi cht khi n ktthc hotng bnh thng,hocgpphingoil khng thchintipc. Trong trnghpcbit,bn c thgi hmstop() kt thc (gitcht)mtlung.

Mc u tin ca cc lung Trong Java, milung c mtmcu tin thchinnhtnh. Khi chng trnh chnh thchinsto ra lung chnh, lung cha.

Lung ny sto ra cc lung con, v cthtiptc.


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Theo mcnh,mtlungskthamcu tin calung chaca n. Bn c th tng hay gim mc u tin ca lungbngcch sdng hm setPriority().

Mc u tin ca cc lung c th t li trong khong tMIN_PRIORITY(Trong lp Thread c mc nh bng 1) vMAX_PRIORITY (mc nh bng 10), hoc NORM_PRIORITY(mc nh l 5).

Lung c mcu tin cao nhttiptcthchin cho n khi:+ N nhngquyniukhin cho lung khcbng cch gi hm yield()+ N dngthchin(bdeadhocchuyn sang trng thibchn).

c mtlungvimcu tin cao hn vo trng thiRunnable.

Mc u tin ca cc lung Vnny sinh l chnlung no thchin khi c nhiuhn

mt lung sn sng thc hin v c cng mt mc u tin caonht? Ni chung, mtscssdngblplch lachnngu


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nhin, hoclachn chng thchin theo thtxuthin.Vd:

Chng ta hy xt chng trnh hinth cc qu bng mu xanhhocny(chuyn) theo nhngngnhtnh.

Mi khi nhn nt Blueball th c 5 lung c to ra vimcu tin thng thng (mc 5) hin th v di chuyn ccqu bng xanh.

Khi nhn nt Redball th cng c 5 lungc to ra vimcu tin (mc 7) cao hnmc thng thnghinth v dichuyn cc qu bng .

kt thc tr chibnnhn nt Close.

Mc u tin ca cc lungimport java.awt.*;import java.awt.event.*;import javax.swing.*;public class Bounce{


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public static void main(String arg[]){JFrame fr = new BounceFrame();fr.show();

}}class BounceFrame extends JFrame{

public BounceFrame(){setSize(300, 200);setTitle("Bong chuyen");addWindowListener(new WindowAdapter(){

public void windowClosing(WindowEvent e){

System.exit(0);}});

Mc u tin ca cc lungContainer contentPane = getContentPane();canvas = new JPanel();contentPane.add(canvas, "Center");JPanel p = new JPanel();


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addButton(p, "Blue ball", new ActionListener(){public void actionPerformed(ActionEvent evt){for(int i = 0; i < 5; i++){

Ball b = new Ball(canvas, Color.blue);b.setPriority(Thread.NORM_PRIORITY);b.start(); }

}});addButton(p, "Red ball", new ActionListener(){

public void actionPerformed(ActionEvent evt){for(int i = 0; i < 5; i++){

Ball b = new Ball(canvas, Color.red);b.setPriority(Thread.NORM_PRIORITY + 2);b.start();

}}

});

Mc u tin ca cc lungaddButton(p, "Close", new ActionListener(){public void actionPerformed(ActionEvent evt){

canvas.setVisible(false);System.exit(0);


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}});contentPane.add(p, "South");}public void addButton(Container c, String title, ActionListener a){

JButton b = new JButton(title);c.add(b);b.addActionListener(a);

}private JPanel canvas;

}

Mc u tin ca cc lungclass Ball extends Thread{public Ball(JPanel b, Color c){

box = b; color = c;}public void draw(){


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Graphics g = box.getGraphics(); g.setColor(color);g.fillOval(x, y, XSIZE, YSIZE); g.dispose();

}public void move(){

if(!box.isVisible()) return;Graphics g = box.getGraphics();

g.setXORMode(box.getBackground()); g.setColor(color);g.fillOval(x, y, XSIZE, YSIZE);x += dx; y += dy;Dimension d = box.getSize();if(x < 0){

x = 0; dx = -dx;

}if(x + XSIZE >= d.width){x = d.width - XSIZE; dx = -dx;

}if(y < 0){

y = 0; dy = -dy; }

Mc u tin ca cc lungif(y + YSIZE >= d.height){y = d.height - YSIZE; dy = -dy;

}g.fillOval(x, y, XSIZE, YSIZE);g.dispose();


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}public void run(){

try{for(int i = 1; i


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Chychng trnh trn chng ta nhnthy hnh nhnhngqu bng ny nhanhhn v cc lungthchin chng c mcu tin cao hn.

Lu : Cc lung c mcu tin thphns khng c chithchinnunhnglungcao hn khng nhng, hocnhngbng hm yield(). Nu c nhng lung

angtrng thi Runnable m c mcu tin t nhtbngmcu tin calungvanhng th mt trong s chng cxplchthchin.+ Blplchthng xuyn tnh limcu tin ca cc lungangthchin+ Tm lung c mcu tin cao nhtthchin.


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S ng b

Khi hi t ti d


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Khi nhiu tuyn truy cp ti nguyn dngchung

Ti nguyn khng th chia x, khi ti

nguyn c thb ph hngVd : Mt lungcd liu, trong khi lung

khc li thay i

Cn cho php mt lung hon thnh tc vca n, ri cho php lungktipthc thi

S ng b

Th ti /


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Thm nhp cc ti nguyn/d liubinhiutuyn

Sngb (Synchronization)

S quan st (Monitor)

S ng b thm nhp s quan st ca mt i

tng, lp trnh vin s dng t khasynchronized khi khai bo phngthc.


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Mi mt i tng s c mt b qun lkha, ch cho mt phng thcsynchronized ca i tng chy ti

mtthiim Khi mt tuyn ang c thc thi trong

phm vi mt phng thc ng b(synchronized), bt k tuyn khc hocphngthcngb khc m cgnggin trong thi gian sphii

ng b ho Cc lung chia svi nhau cng mt khng gian

bnh,ngha l chng c th chia svi nhau cc

i


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ti nguyn. Khi c nhiuhnmt lung cng munsdng

mt ti nguyn sxuthin tnh trngcngthng,ch cho php mtlungcquyn truy cp.

cho cc lung chia s vi nhau c cc tinguyn v hotnghiuqu, lun mbonhtqun dliu thphi c cchngb chng.

ng b ho Muchtcasngb l khi nimmonitor

(gim st) hay cn gi l semaphore(chiu)

Khi i h h d


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Khi nimsemaphore thngcsdngiu khin ngb cc hot ng truy cp vonhng ti nguyn dng chung.

Mt lung mun truy cp vo mt ti nguyndng chung (nhbin d liu) th trc tin n

phi yu cu c c monitorring.

Khi c c monitor th lungnh c cchakhomca vo mintranhchpsdngnhng ti nguyn .

ng b ho Cch monitorthchin hai nguyn tcngb chnh:

+ Khng mt lung no khc c phn monitor khi cmt lung

cu

ang chim gi Nhng lung

i hi h h khi i ii h


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yu v . c yucu monitorsphichcho n khi monitor cgii phng.

+ Khi c mtlunggii phng (ra khi) monitor,mtlungang ch monitor c th truy cp vo ti nguyn dng chungtngngvi monitor .

Miitng trong Java u c monitor, miitng c thcsdngnhmt kho loitr nhau, cung cpkhnngngb truy cp vo nhng ti nguyn chia s.

Trong lp trnh c hai cch thchinngb:

+ Cc hm cngb

+ Cc khicngb

ng b hoCc hm ngb Hm ca mt lp ch cho php mt lung c thc

hi hi i h hi kh i b h i d


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hinmtthiim th nphi khai bo synchronized,cgi l hm ngb. Mtlungmunthchin hm ngb th nphich

c c monitor caitng c hm .

Trong khi mtlungangthchin hm ngb th ttc cc lung khc mun thc hin hm ny ca cngmtitng,uphichcho n khi lungthchin xong v cgii phng.

Bng cch ,nhng hm cngbs khng baogibtcnghn.

ng b hoCc hm ngb Nhng hm khng cngbcaitng c th

i th hi i l bi bt k i t


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cgithchinmi lcbibtkitng no. Khi chy,chng trnh s thi hnh tunt cc lnh cho

n khi kt thc chng trnh. Trong Java, hm ngb c th khai bo static. Cc lp

cng c th c cc monitor tngtnhivi cc itng.

Mtlung yu cu monitor calptrc khi n c ththchinvi mt hm cngb tnh (static) no

trong lp,ngthi cc lung khc munthchinnhng hm nhthca cng mtlp thbchnli.

ng b haVd: Hthng ngn hng c 10 ti khon, trong c cc giao

dch chuyn tin gia cc ti khon vi nhau mt cch ngunhin. Chng trnh to ra 10 lung cho 10 ti khon. Mi giao

d h t l h h t l ti


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dch c mt lungphc v s chuyn mt lng tin ngunhin tmt ti khon sang ti khon khc.Nuchng trnh thchinvi 10 lunghotng khng ng

bchuyntingia cc ti khon trong ngn hng. Vnsny sinh khi c hai lungngthimunchuyntin

vo cng mt ti khon. Gis hai lung cng thchin:accounts[to] += amount;

Cu lnh ny cthchinnh sau:1. Np accounts[to] vo thanh ghi.2. Cngstin trong ti khon accounts vi amount3. Luliktqu cho accounts[to].

ng b haChng ta c thgi thit lung thnht thchinbc 1 v 2vi amount = 500, sau nbngt. Lungth hai c ththchintrnvnc babc trn vi amount = 1000, sau lung

th ht kt th i ht b h th hi t b 3


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263

thnhtkt thc viccpnhtbng cch thchinntbc 3.Qu trnh ny c m tnhhnh sau :Lung 1 Lung 2 accounts[to]

Thanh ghi 1 Thanh ghi 2

NpCng NpCng

Luli LuliKt thc lungthnht,accounts[to]c 6000, nhng ngay sau lungth hai kt thc th cng chnh ti khon cha chuyn tin i u c,nhnglich cn 5500. ng ra nphi l 6500

5000

5500

5500

5000

6000

6000

5000

5000

5000

5000

6000

5500

ng b haJavasdngcchngb kh hiuqu l monitor. Mthm s khngbngtnubn khai bo n l synchronized.public synchronized void transfer(int from, int to, int

amount){if(accounts[from] < amount) return;


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if(accounts[from] < amount) return;accounts[from] -= amount;accounts[to] += amount;numTransacts++;if(numTransacts % NTEST == 0) test();

}public synchronized void test(){

int sum = 0;for(int i = 0; i < accounts.length; i++)

sum += accounts[i];

System.out.println("Giao dich: " + numTransacts+ " tong so: " + sum);

}

ng b haKhi c mtlunggi hm cngb th n cmborng hm ny

phi thchin xong th lung khc micsdngivi cng mtitng.

Hot ng ca cc lung khng ng b v ng b ca hai lung thc hin


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Hotngca cc lung khng ngb v ngbca hai lungthchingi hm transfer()

Khng cngb cngb

Thread 1 Thread 2 Thread 1 Thread 2

transfer() transfer()

transfer()

transfer()

Cc kho i tngKhi mt lunggimt hm cngb th i

tngca nbkho,gingnh kho ca phng.

Nh khi t l kh i h


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Nhvy, khi mt lung khc mungi hm cngb ca cng i tng th s khng mc.

Sau khi thc hin xong, lung bn trong gii

phng hm cngbvasdng, ra khiitng v a cha kho ra ngoibccanhnglung khc c thtiptc cng vicca mnh.

Cc kho i tng Mtlung c thginhiu kho itngcng mtthiim,

nhtrong khi angthchinmtligi hm ngbcamtitng, n ligitip hm ngbcaitng khc.

Nhng ti mi thi im mi kho i tng ch c mt lung h


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Nhng,timithiim,mi kho itngchcmtlungshu.Chng ta hy phn tch chi tithnhotngcahthng ngnhng. Mt giao dch chuyn tin s khng thc hin c nukhng cn tin. N phichcho n cc ti khon khc chuyn

tinn v khi c th mithchinc giao dch.public synchronized void transfer(int from, int to, int amount){while(accounts[from] < amount)

wait();//Chuyntin

}


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Cc kho i tngNhng lunga ra khi danh sch hng i scb lp lch kchhot chng. Ngay tckhclung no chimc kho itng th sbtuthchin. Nhvy, trong hm transfer() chng ta gi notifyAll()khi kt thc vicchuyntinmt trong cc lung c thctiptc

thc hin v trnh b tc.


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thchin v trnh btc.Cui cng chng trnh sdngcchngbcvitlinh sau.public class SynBankTransfer{

public static void main(String arg[]){Bank b = new Bank(NACCOUNTS, INI_BALANCE);

for(int i = 0; i < NACCOUNTS; i++){TransferThread t = new TransferThread(b, i, INI_BALANCE);t.setPriority(Thread.NORM_PRIORITY + i % 2);t.start();

}

}public static final int NACCOUNTS = 10;public static final int INI_BALANCE = 10000;

}

Cc kho i tngclass Bank{

public static final int NTEST = 1000;private int[] accounts;private long numTransacts = 0;public Bank(int n int initBalance){


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public Bank(int n, int initBalance){accounts = new int[n];for(int i = 0; i < accounts.length; i++)

accounts[i] = initBalance;numTransacts = 0;

}public void transfer(int from, int to, int amount){

while(accounts[from] < amount) wait();accounts[from] -= amount;accounts[to] += amount;

numTransacts++;notifyAll();if(numTransacts % NTEST == 0) test();

}

Cc kho i tngpublic synchronized void test(){int sum = 0;for(int i = 0; i < accounts.length; i++)

sum += accounts[i];

System out println("Giao dich: " + numTransacts + " tong so: " + sum);


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System.out.println( Giao dich: + numTransacts + tong so: + sum);}

public int size(){return accounts.length;

}}class TransferThread extends Thread{

private Bank bank;private int fromAcc;private int maxAmount;

public TransferThread(Bank b, int from, int max){bank = b;fromAcc = from; maxAmount = max;

}

Cc kho i tngpublic void run(){

try{

while(!interrupted()){

int toAcc = (int)(bank.size() * Math.random());


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int toAcc (int)(bank.size() Math.random());int amount = (int)(maxAmount * Math.random());

bank.transfer(fromAcc, toAcc, amount);

sleep(1);

}

}catch(InterruptedException e){}

}

}

Nubn chy chng trnh vi cc hm transfer(), test() cngb th

mivicsthchin chnh xc ng theo yu cu. Tuy nhin, bncng cthnhnthychng trnh schychmhn cht tbi vphitr gi cho cchngbnhmmbo cho hthnghotng chnh xc, mbonhtqun dliu,hoc trnh gy ra tcnghn.

Deadlock

Mt deadlock xy ra khi hai tuyn c


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Mt deadlock xy ra khi hai tuyn cmtphthuc vng quanh trn mtcpitngngb

Vn cht tcC ch ng b trong Java l rt tin li, kh mnh,

nhng khng giiquytcmivnny sinh trong qutrnh xl alung.

V d : Account 1 c 2000$ Account 2 c 3000$ v Thread 1


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Vd : Account 1 c 2000$, Account 2 c 3000$ v Thread 1cn chuyn 3000$ t Account 1 sang Account 2, ngc liThread 2 cnchuyn 3500$ tAccount 2 sang Account 1.

Khi , Thread 1 v Thread 2 ri vo tnh trng cht

tc,hoctcnghn v chng chnln nhau.Mththngm ttc cc lung(tin trnh) bchnli

chln nhau v khng mtlung(tin trnh) no thchintipth cgil hthngbchttc(tcnghn).

Trong tnh hungtrn,c hai lunguphigi wait()xl hai ti khonu khng stinchuyn.

Vn cht tcTrong chng trnh SynBankTransfer.java, hin

tngtcnghn khng xuthinbimt l do ngin. Migiao dchchuyntinnhiunht l 10000$.

C 10 ti khon vi tng s tin l 100000$ Do mi


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C 10 ti khonvitngstin l 100000$. Do ,mithiimu c t nhtmt ti khon c khng t hn 10000$,ngha l lungph trch ti khonc php thchin.

Tuy nhin, khi lp trnh ta c th gy ra tnh hung khcc th lm xuthintcnghn

Vn cht tcVd :Trong SynBankTransfer.java thay v gi

notifyAll() ta ginotify().

Nh trn phn tch notifyAll() thng bo cho


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Nh trn phn tch, notifyAll() thng bo chottc cc lungangch c tinchuyni c thtiptcthchin, cn notify()ch bo cho mtlungctiptc.

Khi ,nulungc thng bo li khng ththchin,v khng tin chuyn chng hn, th tt c cc lungkhc cngsbchnli.

Vn cht tc Chng ta hy xt kchbn sau:

+Account 1: 19000$

+ Ttc ccAccount cn liu c 9000$

+ Thread 1: chuyn 9500$ tAccount 1 sangAccount 2

+ Ttlung khc uchuyn sang ti khon khc mtlngtin l 9100$.


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g y gCh c Thread1tinchuyn cn cc lung khc bchnli. Thread1thchin

chuyntin xong ta c:+Account 1: 9500$

+Account 2: 18500$

+ Ttc ccAccount cn liu c 9000$

GisThread 1ginotify(). Hm ny ch thng bo cho mtlungngu nhin n c th tip tc thchin. Gis l Thread3. Nhng lung ny cng khng chuync v khng tinti khonAccount3, nn phich(giwait()). Thread 1vntiptcthchin. Mt giao dchmingu nhin licto ra. Vd

Thread 1: chuyn 9600$ tAccount1 sangAccount 2.

By giThreadligiwait(), v nhvyttc cc lunguri vo tnh trngtcnghn.

Qua vd trn cho thy,mtngn nglp trnh c cchhtrngb l chagiiquytvntcnghn. Quan trng l khi thitkchng trnh, ta phimborngmithiim c t nhtmtlung(tin trnh) tiptcthchin.

Phngthc finalize()

Java cung cp mt cch lm sch mt tintrnh trc khi iu khin tr li h iu hnh


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Java cung cpmt cch lm schmttintrnh trc khi iukhintrlihiu hnh Phng thc finalize(), nu hin din, s

c thc thi trn mi i tng, trc khi

sdn rc Cu lnhcaphngthc finalize() nh sau: protected void finalize( ) throws Throwable

Tham chiu khng phi l sdn rc; ch ccitngmicdn rc

Ch VIII


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Chng VIII

Cc lung I/O

Cc lung

Cc lung l nhng ng ng gi v


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Cc lung l nhng ng ng gi vnhn thng tin trong cc chng trnh java.

Khi mt lungchoc ghi, cc lung khc

b kho. Nu li xy ra trong khi choc ghi lung,

mtbitlscto ra.

Lpjava.lang.Systemnhnghalungnhpv xutchun.

Cc lplung I/O

Lp System out


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Lp System.out.

Lp System.in.

Lp System.err.

Cc lp lung I/O

x l mi loid liu, java chia lung

thnh 2 loi : lung byte ( byte stream) vl k t ( h t t )


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thnh 2 loi : lung byte ( byte stream) vlung k t (character stream) Lp InputStream v OutputStream l hai

lp c s cho mi lung nhp xut hngbyte

Lp Reader/ Writer hai lpc scho vicc ghi hng k t

Lp nhp xut hng k t Reader v Writer l hai lpcstrutng

cho lung hng k t


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cho lunghng k t Cung cp mt giao din chung cho tt c

cc lpc ghi hng k t

Mi ln c/ghi ra lung th c 2 bytetngngvimt k t

M hnh phn cp c/ghi hng k t


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Lp Reader

Lp Reader v InputStream c mt giao din


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Lp Reader v InputStream c mt giao dinging nhau, chng ch khc nhau v kiu d liuu vo

Lp Reader c cc phng thc c mt k t

hoc mng cc k t Cc phng thc: int read()

int read(char cbuf[])

int read(char cbuf[], int offset, int length)

Lp Writer

Lp Writer v OutputStream c mt giao

din ging nhau chng ch khc nhau v


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din ging nhau, chng ch khc nhau vkiudliuu vo

Lp Writer nhngha cc phng thc

ghi mt k thocmng cc k t ra lung Cc phngthc:int write(int c)

int write(char cbuf[])int write(char cbuf[], int offset, int length)

Lp Writer

H tr cc phng thc sau :


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Htr cc phngthc sau : flush( )

close( )

Nhp/xut chui v mng kt

H tr nhp v xut t cc vng m


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H trnhp v xut t cc vng mbnh

Htr 8 bt k tnhp v ktxut

Lp CharArrayReader khng b sungphng thc mi vo cc phng

thc m lpReader cung cp.

Nhp/xut chui v mng k t

Lp CharArrayWriter b sung phng


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Lp CharArrayWriter b sung phngthc sau y vo phngthccalpWriter cung cp:

reset( ) size( )

toCharArray( )

toString( )

writeTo( )

Nhp/xut chui v mng k t

LpStringReadertr gip c cc k tu t h i


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Lp StringReader tr g p c t uvo t su chui.

N khng b sung bt k phng thc nom lp Reader cung cp.

Lp StringWriter tr gip ghi lung ktxut k t ra mtitngStringBuffer.

Lp ny b sung thm cc phngthc sau: getBuffer( )

toString( )

Lp hng byte

c thc ghi 1 byte, ta sdng lung

hng byte


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hng byte Hai lp InputStream v OutputStream l hai

lp c s tru tng cho cc lunghng

byte Mi ln c/ghi ra lung th c 8 bits ra

lung

M hnh phn cp c/ghi hng byte


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Lp InputStream L lptrutng nhngha cch nhnd liu

Cung cp s phng thc dng


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g cp s phng thc g c v cc lungdliu lm u vo.

Trong lp InputStream c cc phng thc

cho vic c mt byte hoc mng cc byte Cc phngthc: int read()

int read(byte cbuf[])

int read(byte cbuf[], int offset, int length)

Lp OutputStream

L lptrutng. h h h hi d li l


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p g nhngha cch ghi dliu vo lung. Cung cp tp cc phng thc tr gip

trong victo, ghi v x l cc lungxut.

Lp OutputStream c cc phng thc ghimt byte hoc mng cc byte ra lung

Cc phng thc: write(int c)

write(byte cbuf[ ])

write(byte[ ], int offset, int length)

Nhp mng cc Byte

Sdng cc mbnh


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S dng m b nh LpByteArrayInputStream

To ra mt lungnhptmbnh

vmng cc byte. Khng htr cc phngthcmi

Cc phng thc np chng ca lp

InputStream, ging nh read(), skip(),available() v reset().

Xut mng cc Byte

sdng cc vng mbnh


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s dng g m b nh Lp ByteArrayOutputStream

To ra mtlungktxut trn mng byte

Cung cp cc kh nng b sung chomng kt xut tng trng nhm chachcho dliumi ghi vo.

Cng cung cp cc phng thc

chuyn i lung ti mng byte, hay itng String.

Phng thc ca lp

ByteArrayOutputStream :reset( )


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y y p reset( )

size( )

writeTo( )

Cc lp nhp/xut tp tin Cc lp ny tr gip trong Java h tr

cc thao tc nhp v xut: File


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p FileDescriptor FileInputStream FileOutputStream FileReader FileWriter

Cc lp File, FileDescriptor, vRandomAccessFile c s dng h tr

trc tip hoc truy cp nhp/xut ngunhin.

Lptp tin

csdng truy cp cc itngtp tinv th mc


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g p g pv thmc

Nhng tp tin c tn ct tn theo quiccahiu hnh.

Lp ny cung cpphngthckhitoto ra cc thmc v tp tin

Ttc cc thao tc thmc v tp tin ucsdng cc phngthc truy cp vcc phngthcthmc m cc lptp tincung cp

Lptp tin

x l tp tin ngoi tr, ta s dng ccl li t ti h


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p g , glung lin quan n tp tin nh :FileInputStream, FileOutputStream,FileReader, FileWriter

FileInputStream v FileOutputStream phcv cho vicc ghi tp tin hng Byte

FileReader v FileWriter phcv cho vic

c ghi tp tin hng k t

Cc hm to ca cc lp tng ng lin ktlung vi mt tp tin c th

public void FileInputStream ( String FileName)


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p ( g ) public void FileInputStream ( File file)

public void FileOutputStream ( String FileName)

public void FileOutputStream (File file) public void FileWriter ( String FileName)

public void FileWriter (File file)

public void FileReader ( String FileName) public void FileReader (File file)

Nhp / xut lc Lc:

vcbncsdng thch ng cc

lung theo cc nhu cucachng trnhth


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g gcth.

B lc nm gia lung nhp v lung

xut. Thc hin mt s tin trnh c bit trn

cc byte c chuyn giao t u vonktxut.

C thphihpthchinmt dy cctuchnlc.

Lp FilterInputStream

L lptrutng.L h tt l l h l


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g L cha cattc cc lplungnhplc. Cung cp kh nng to ra mt lung t

lung khc.

Mt lung c th c v cung cp didngktxut cho lung khc.

Duy tr mt dy cc i tng ca lp

InputStream Cho php to ra nhiublckt xch

Lp FilterOutputStream

L dngbtr cho lpFilterInputStream.L cha ca tt c cc lp l ng kt t


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L cha cattc cc lplungktxut. Duy tr i tng ca lp OutputStream

nh l mtbinout. Dliu ghi ra lp ny c thsaithc

hin cc thao tc lc, v sau phnhinitngOutputStream.

Vng mnhp/xut

V cc thao tc vicng,mngthng lu hn so

vi thao tc bnh trong K thut s dng vng m nhm tng tc


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K thut s dng vng m nhm tng tc c/ghi

Vikthut vng msgimcslnc/ghilung

Trong Java ta c thto ra vng mca cc lp :

BufferInputStreamBufferOutputStreamBufferReaderBufferWriter

Vng mnhp/xut

Vng m:

L kho lutrdliu.C th cung cp d liu thay v quay tr li ngun


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C th cung cpdliu thay v quay trlingundliugc ban u.

Java sdng vng mnhp v ktxuttm

thilp cache dliucchoc ghi vo mtlung. Trong khi thchin vng mnhp:

S lng by

giaotrinhjava1234

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