cleancode-110520031623-phpapp02

8/11/2019 cleancode-110520031623-phpapp02

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CLEAN CODE

Arturo Herrero


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Two reasons

2. You want to be a better programmer1. You are aprogrammer


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The Boy Scout Rule

Uncle BobRobert C. Martin


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Elegance

Bjarne Stroustrup

I lie m! co"e to beelegant an" e##icient

Clean co"e "oes onet$ing well


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Simple, direct, prose

Clean co"e is simplean" "irect

Clean co"e rea"s liewell%written prose

&ra"! Booc$


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Literate

Clean co"e can berea"

Clean co"e s$oul" beliterate

'a(e )$omas


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Care

Clean co"e alwa!s

loos lie it was writtenb! someone w$o cares

Mic$ael *eat$ers


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Small, epressi!e, simple

Re"uce" "uplication+

Ron ,e##ries

$ig$ e-pressi(eness+an" earl! buil"ing o#+simple abstractions


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"hat you epected

woring on clean co"e

ar" Cunning$am

w$en eac$ routine !ourea"s turns out to beprett! muc$ w$at !ou

You now !ou are

e-pecte"


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#eaning$ul Names

public List getThem() { List list1 = new ArrayList(); !r (int[] " # theList) i ("[$] == %)

list1&a''("); return list1;

Use Intention%Re(ealing /ames


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#eaning$ul Names

public List get*lagge'ells() { List lagge'ells = new ArrayList(); !r (ell cell # game+!ar') i (cell&is*lagge'())

lagge'ells&a''(cell); return lagge'ells;

Use Intention%Re(ealing /ames


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#eaning$ul Names

class ta2cr'1$/ { pri-ate ate genym'hms; pri-ate ate m!'ym'hms; pri-ate inal 3tring ps45int = 61$/6;

78 &&& 87;

Use 0ronounceable /ames


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#eaning$ul Names

class ust!mer { pri-ate ate generati!nTimestamp; pri-ate ate m!'iicati!nTimestamp;; pri-ate inal 3tring rec!r'9' = 61$/6;

78 &&& 87;

Use 0ronounceable /ames


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#eaning$ul Names

!r (int : = $; : < %; :00) {

s 0= (t[:] 8 %) 7 ;

Use Searc$able /ames


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#eaning$ul Names

int realayser9'ealay = %;c!nst int ,2?@A3@B2@BB? = ;int sum = $;!r (int : = $; : < CDE+B2@,*@TA3?3; :00) {

int realTasFays = tasFBstimate[:] 8realayser9'ealay; int realTasFeeFs = (real'ays 7 ,2?@A3@B2@BB?); sum 0= realTasFeeFs;

Use Searc$able /ames


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#eaning$ul Names

public class art { pri-ate 3tring m@'sc; 77 The te"tual 'escripti!n -!i' setCame(3tring name) { m@'sc = name;

Member 0re#i-es A(oi" enco"ings

Hungarian /otation A(oi" enco"ingsh!neCumber ph!ne3tring;77 name n!t change' when type change'G


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#eaning$ul Names

public class art { 3tring 'escripti!n; -!i' setescripti!n(3tring 'escripti!n) { this&'escripti!n = 'escripti!n;

Member 0re#i-es A(oi" enco"ings

Hungarian /otation A(oi" enco"ingsh!neCumber ph!ne;


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#eaning$ul Names

!r (a = $; a < 1$; a00) !r (b = $; b < 1$; b00)

A(oi" Mental Mapping

Class /amesEanager. r!cess!r. ata. 9n!


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#eaning$ul Names

!r (i = $; i < 1$; i00) !r (: = $; : < 1$; :00)

A(oi" Mental Mapping

Class /amesust!mer. iFiage. Acc!unt. A''ressarser77 a class name sh!ul' n!t be a -erb


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#eaning$ul Names

p!stayment. 'eleteage. sa-e77 meth!'s sh!ul' ha-e -erb !r -erb phrase names

string name = empl!yee&getCame();cust!mer&setCame(6miFe6);i (paychecF&is!ste'())&&&

!mple" ulcrum!int = !mple"&r!m2ealCumber(/&$);

77 is generally better than!mple" ulcrum!int = new !mple"(/&$);

Met$o" /ames


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#eaning$ul Names

etch. retrie-e. get 77 as e5ui-alent meth!'s

c!ntr!ller. manager. 'ri-er 77 c!nusing

0ic 3ne or" per Concept

'on4t 0un77 a-!i' using the same w!r' !r tw! purp!ses


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#eaning$ul Names

Acc!untHisit!r. I!bJueue77 pe!ple wh! rea' y!ur c!'e will be pr!grammers

Use Solution 'omain /ames

A"" Meaning#ul Conte-tirstCame. lastCame. street. city. state. 4ipc!'e77 a better s!luti!na''r*irstCame. a''rLastCame. a''r3tate

77 a better s!luti!nlass A''ress


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#eaning$ul Names

A''ress77 is a ine name !r a class

Acc!untA''ress. ust!merA''ress

77 are ine names !r instances ! the class A''ress77 but c!ul' be p!!r names !r classes

EA a''resses. p!rt a''resses. eb a''resses77 a better s!luti!n

!stalA''ress. EA. D29

'on4t A"" &ratuitous Conte-t


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%unctions

77 rules ! uncti!ns#77 1& sh!ul' be small77 /& sh!ul' be smaller than that

77 < 1$ characters per line77 < /$ lines

Small5

'o 3ne )$ing77 *DCT9,C3 3K,DL , ,CB TK9C& TKB 3K,DL , 9T BLL&77 TKB 3K,DL , 9T ,CL&


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%unctions

77 high le-el ! abstracti!n getKtml()

77 interme'iate le-el ! abstracti!n

3tring pageathCame = atharser&ren'er(pageath);

77 remarFably l!w le-el &appen'(6Mn6)

3ne 6e(el o# Abstraction per *unction

Rea"ing Co"e #rom )op to Bottom77 the 3tep'!wn 2ule


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%unctions

class Bmpl!yee&&& int payAm!unt() { switch (getType()) { case Bmpl!yeeType&BC9CBB2#

return @m!nthly3alary; case Bmpl!yeeType&3ALB3EAC# return @m!nthly3alary 0 @c!mmissi!n; case Bmpl!yeeType&EACAB2# return @m!nthly3alary 0 @b!nus; 'eault#

thr!w new B"cepti!n(69nc!rrect Bmpl!yee6);

Switc$ Statements


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%unctions

class Bmpl!yeeType&&& abstract int payAm!unt(Bmpl!yee emp);

class 3alesman&&&

int payAm!unt(Bmpl!yee emp) { return emp&getE!nthly3alary() 0 emp&get!mmissi!n(

class Eanager&&& int payAm!unt(Bmpl!yee emp) {

return emp&getE!nthly3alary() 0 emp&get+!nus();

Switc$ Statements


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%unctions

testableKtml => inclu'e3etupAn'Tear'!wnages

inclu'e3etupAn'Tear'!wnages. inclu'e3etupages.inclu'e3uite3etupage. inclu'e3etupage

77 what happene' t!inclu'eTear'!wnages. inclu'e3uiteTear'!wnage.inclu'eTear'!wnage

Use 'escripti(e /ames

*unction Arguments77 the i'eal number ! arguments !r a uncti!n is 4er!


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%unctions

77 i a uncti!n is g!ing t! trans!rm its input argument.77 the trans!rmati!n sh!ul' appear as the return -alue

3tring+uer trans!rm(3tring+uer in)

77 is better than-!i' trans!rm(3tring+uer !ut)

Common Mona"ic *orms

*lag Argumentsren'er(true)


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%unctions

77 asFing a 5uesti!n ab!ut that argumentb!!lean ileB"ists(NEy*ileO)

77 !perating !n that argument. trans!rming an' returning

9nput3tream ile,pen(NEy*ileO)

77 e-ent. use the argument t! alter the state ! the syste-!i' passw!r'Attempt*aile'Ctimes(int attempts)

Common Mona"ic *orms

*lag Argumentsren'er*!r3uite()ren'er*!r3ingleTest()


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%unctions

write*iel'(name)77 is easier t! un'erstan' thanwrite*iel'(!utput3tream. name)

77 perectly reas!nable!int p = new !int($.$)

77 pr!blematicassertB5uals(e"pecte'. actual)

'!a"ic *unctions

)ria"sassertB5uals(message. e"pecte'. actual)


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%unctions

ircle maFeircle('!uble ". '!uble y. '!uble ra'ius);ircle maFeircle(!int center. '!uble ra'ius);

Argument 3bjects

7erbs an" 8e!wor"swrite(name)write*iel'(name)

assertB5uals(e"pecte'. actual)

assertB"pecte'B5ualsActual(e"pecte'. actual)


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%unctions

77 '! s!mething !r answer s!mething. but n!t b!thpublic b!!lean set(3tring attribute. 3tring -alue);

setAn'hecF9B"ists

i (attributeB"ists(6username6)) { setAttribute(6username6. 6uncleb!b6); &&&

Ha(e /o Si"e 9##ects


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%unctions

77 'uplicati!n may be the r!!t ! all e-il in s!tware'on4t Repeat Yoursel# 'RY

Structure" 0rogramming77 B'sger i:FstraPs rules77 !ne entry77 !ne e"it

77 uncti!ns small

77 !ccasi!nal multiple return. breaF. !r c!ntinue statemen77 can s!metimes e-en be m!re e"pressi-e i:FstraPs rules


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Comments

77 '!nPt c!mment ba' c!'e. rewrite itGComments 'o /ot Mae Up #or Ba" Co"e

9-plain Yoursel# in Co"e77 hecF t! see i the empl!yee is eligible !r ullbeneitsi ((empl!yee&lags Q K,D2L@*LA) QQ (empl!yee&age > R))

i (empl!yee&isBligible*!r*ull+eneits())


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Comments &good'

77 !pyright () /$11 by ,s!c!& All rights reser-e'&77 2elease' un'er the terms ! the CD eneral ublicLicense 77 -ersi!n / !r later&

6egal Comments

In#ormati(e Comments77 2eturns an instance ! the 2esp!n'er being teste'&pr!tecte' abstract 2esp!n'er resp!n'er9nstance();77 renaming the uncti!n# resp!n'er+eingTeste'

77 !rmat matche' FF#mm#ss BBB. EEE ''. yyyyattern timeEatcher = attern&c!mpile(6MM'8#MM'8#MM'8 MMw8. MMw8 MM'8. MM'86);


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Comments &good'

77This is !ur best attempt t! get a race c!n'iti!n77by creating large number ! threa's&!r (int i = $; i < /$$$; i00) { i'get+uil'erThrea' wi'get+uil'erThrea' =

new i'get+uil'erThrea'(wi'get+uil'er. te"t. ail*lag) Threa' threa' = new Threa'(wi'get+uil'erThrea'); threa'&start();

9-planation o# Intent

Clari#icationassertTrue(a&c!mpareT!(b) == S1); 77 a < bassertTrue(b&c!mpareT!(a) == 1); 77 b > a

C t


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Comments &good'

public static 3impleate*!rmat maFe3tan'ar'Kttpate*!rmat( 773impleate*!rmat is n!t threa' sae. 77s! we nee' t! create each instance in'epen'ently& 3impleate*!rmat ' = new 3impleate*!rmat(6'' EE yyyy

'&setTime!ne(Time!ne&getTime!ne(6ET6)); return ';

arning o# Conse:uences

)3'3 Comments77T,,SE'E these are n!t nee'e'77 e e"pect this t! g! away when we '! the checF!ut m!'el

C t


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Comments &good'

3tring list9tem!ntent = match&gr!up()&trim();77 the trim is real imp!rtant& 9t rem!-es the starting77 spaces that c!ul' cause the item t! be rec!gni4e'77 as an!ther list&

new List9temi'get(this. list9tem!ntent. this&le-el 0 1);return buil'List(te"t&substring(match&en'()));

Ampli#ication

,a(a"ocs in 0ublic A0Is77 there is n!thing 5uite s! helpul an' satisying77 as a wellS'escribe' public A9

C t


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Comments &(ad'

try { 3tring pr!pertiesath = pr!pertiesL!cati!n 0 676 0 2,B2T9B3@*9LB; *ile9nput3tream pr!perties3tream =

new *ile9nput3tream(pr!pertiesath); l!a'e'r!perties&l!a'(pr!perties3tream);catch(9,B"cepti!n e) { 77 C! pr!perties iles means all 'eaults are l!a'e'

Mumbling

C t


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Comments &(ad'

77 Dtility meth!' that returns when this&cl!se' is true&77 Thr!ws an e"cepti!n i the time!ut is reache'&public synchr!ni4e' -!i' wait*!rl!se (inal l!ng time!utEillis) thr!ws B"cepti!

{ i(Gcl!se') { wait(time!utEillis); i(Gcl!se') thr!w new B"cepti!n(6E!cF2esp!nse3en'er c!ul' n!t be cl!se'6);

Re"un"ant Comments

C t


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Comments &(ad'

7888 The pr!cess!r 'elay !r this c!mp!nent&87pr!tecte' int bacFgr!un'r!cess!relay = S1;

7888 The liecycle e-ent supp!rt !r this c!mp!nent&87pr!tecte' Liecycle3upp!rt liecycle = new Liecycle3upp!rt(thi7888 The c!ntainer e-ent listeners !r this !ntainer&87pr!tecte' ArrayList listeners = new ArrayList();

Re"un"ant Comments

C t


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Comments &(ad'

7888 Uparam title The title ! the 8 Uparam auth!r The auth!r ! the 8 Uparam tracFs The number ! tracFs !n the

8 Uparam 'urati!n9nEinutes The 'urati!n ! the in minu87public -!i' a''(3tring title. 3tring auth!r. int tracFs. int 'urati!n9nEinutes) { c' = new (); c'&title = title; c'&auth!r = auth!r; c'&tracFs = tracFs; c'&'urati!n = 'urati!n9nEinutes;

Man"ate" Comments

C t


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Comments &(ad'

8 hanges (r!m 11S,ctS/$$1)8 SSSSSSSSSSSSSSSSSSSSSSSSSS8 11S,ctS/$$1 # 2eS!rganise' the class an' m!-e' it t! new8 pacFage c!m&:reinery&'ate ();

8 $SC!-S/$$1 # A''e' a getescripti!n() meth!'. an'8 eliminate' C!tableate class ();8 1/SC!-S/$$1 # 9+ re5uires setescripti!n() meth!'. n!w8 that C!tableate class is g!ne (); hang8 getre-i!usay,eeF().8 get*!ll!wingay,eeF() an'8 getCearestay,eeF() t! c!rrect bugs ()8 $SecS/$$1 # *i"e' bug in 3prea'sheetate class ();8 /VSEayS/$$/ # E!-e' the m!nth c!nstants int! a separate8 interace (E!nth!nstants) ();

,ournal Comments

Comments


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Comments &(ad'

7888 eault c!nstruct!r&87pr!tecte' Annualate2ule() {

788 The 'ay ! the m!nth& 87pri-ate int 'ay,E!nth;

7888 2eturns the 'ay ! the m!nth&8 Ureturn the 'ay ! the m!nth&87public int getay,E!nth() { return 'ay,E!nth;

/oise Comments

Comments


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Comments &(ad'

788 The name& 87pri-ate 3tring name;

788 The -ersi!n& 87

pri-ate 3tring -ersi!n;

788 The licenceCame& 87pri-ate 3tring licenceCame;

788 The -ersi!n& 87pri-ate 3tring in!;

Scar! /oise

Comments


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Comments &(ad'

77 '!es the m!'ule r!m the gl!bal list


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Comments &(ad'

77 Acti!ns 77777777777777777777777777777777770osition Marers

Closing Brace Commentswhile ((line = in&rea'Line()) G= null) { line!unt00; char!unt 0= line&length(); 3tring w!r's[] = line&split(6MM6); w!r'!unt 0= w!r's&length;

77while

Comments


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Comments &(ad'

78 A''e' by 2icF 87Attributions an" B!lines

Commente"%3ut Co"e9nput3tream2esp!nse resp!nse = new 9nput3tream2esp!nse();resp!nse&set+!'y(!rmatter&get2esult3tream().!rmatter&get+yte!unt());77 9nput3tream results3tream = !rmatter&get2esult3tream()77 3tream2ea'er rea'er = new 3tream2ea'er(results3tream);

77 resp!nse&set!ntent(rea'er&rea'(!rmatter&get+yte!unt(

Comments


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Comments &(ad'

7888 TasF t! run it tests&8 This tasF runs itnesse tests an' publishes the results8

8 8 Dsage#8 Qlt;tasF'e name=Q5u!t;e"ecuteSitnesseStestsQ5u!t;8 classname=Q5u!t;itnesse&ant&B"ecute*itnesseTestsTasFQ58 classpathre=Q5u!t;classpathQ5u!t; 7Qgt;8 ,28 Qlt;tasF'e classpathre=Q5u!t;classpathQ5u!t;8 res!urce=Q5u!t;tasFs&pr!pertiesQ5u!t; 7Qgt;8 8 Qlt;e"ecuteSitnesseStests

H)M6 Comments

Comments &( d'


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Comments &(ad'

7888 !rt !n which itnesse w!ul' run& eaults t! X$X/


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Comments &(ad'

78 2* /$% S Eultipurp!se 9nternet Eail B"tensi!ns (E9EB) art ,ne# *!rmat ! 9nternet Eessage +!'ies secti!n R&X& +aseR% !ntentSTranserSBnc!'ing

The enc!'ing pr!cess represents /%Sbit gr!ups ! input b as !utput strings ! % enc!'e' characters& r!cee'ing r let t! right. a /%Sbit input gr!up is !rme' by c!ncatenating XSbit input gr!ups& These /% bits are then treate' as % c!ncatenate' RSbit gr!ups. each ! which is translate' int! a single 'igit the baseR% alphabet& hen enc!'ing a bit stream -ia the baseR% enc!'ing. the stream must be presume' t! be !r'ere' with the m!stS signiicantSbit irst&87

)oo Muc$ In#ormation

Comments &( d'


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Comments &(ad'

788 start with an array that is big en!ugh t! h!l' all the8 pi"els (plus ilter bytes). an' an e"tra /$$ bytes !r8 hea'er in!

87this&png+ytes = new byte[((this&wi'th 0 1) 8 this&height 8 0 /$$];

Inob(ious Connection

*unction Hea"ers77 sh!rt uncti!ns '!nPt nee' much 'escripti!n

Comments &( d'


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Comments &(ad'

77 e"tra !rmality ! the :a-a'!c c!mments,a(a"ocs in /onpublic Co"e

%ormatting


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%ormatting

77 c!mmunicati!n)$e 0urpose o# *ormatting

)$e /ewspaper Metap$or77 highSle-el S> 'etails

7ertical 3penness Between Concepts77 each blanF line is a -isual cue77 that i'entiies a new an' separate c!ncept

%ormatting


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%ormatting

77 -ertical 'ensity implies cl!se ass!ciati!n

7888 The class name ! the rep!rter listener87pri-ate 3tring m@classCame;

7888 The pr!perties ! the rep!rter listener87pri-ate m@pr!perties = new ArrayList();

7ertical 'ensit!


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%ormatting


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%ormatting

pri-ate -!i' measureLine(3tring line) { line!unt00; int line3i4e = line&length(); t!talhars 0= line3i4e; linei'thKist!gram&a''Line(line3i4e. line!unt); rec!r'i'estLine(line3i4e);

public static '!uble r!!t/(int a. int b. int c) { '!uble 'eterminant = 'eterminant(a. b. c); return (Sb S Eath&s5rt('eterminant)) 7 (/8a);

Hori;ontal 3penness an" 'ensit!


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%ormatting


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%ormatting

public class *itCesseB"pe'iter implements 2esp!nse3en'er{ pri-ate 3!cFet s!cFet; pri-ate 9nput3tream input; pri-ate ,utput3tream !utput; pri-ate 2e5uest re5uest; pri-ate 2esp!nse resp!nse; pri-ate *itCesse!nte"t c!nte"t; pr!tecte' l!ng re5uestarsingTimeLimit; pri-ate l!ng re5uestr!gress; pri-ate l!ng re5uestarsingea'line;

pri-ate b!!lean hasBrr!r; &&&

Hori;ontal Alignment

%ormatting


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%ormatting

public class !mmenti'get e"ten's Te"ti'get { public static inal 3tring 2BBY = 6Z[ZMrMn]8(W#(W#MrMn)\Mn\Mr)W6; public !mmenti'get(3tring te"t) { super(te"t); public 3tring ren'er() thr!ws B"cepti!n { return 66;

Breaing In"entation

%ormatting


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%ormatting

public class !mmenti'get e"ten's Te"ti'get { public static inal 3tring 2BBY = 6Z[ZMrMn]8(W#(W#MrMn)\Mn\Mr)W6;

public !mmenti'get(3tring te"t) { super(te"t);

public 3tring ren'er() thr!ws B"cepti!n { return 66;

Breaing In"entation

%ormatting


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%ormatting

77 e-ery pr!grammer has his !wn a-!rite !rmatting rules77 but i he w!rFs in a team77 then the team rules

)eam Rules

O()ects and Data Structures


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) a a a

!ncrete !int

public class !int { public '!uble "; public '!uble y;

'ata Abstraction



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)

Abstract !int

public interace !int { '!uble getY(); '!uble get(); -!i' setartesian('!uble ". '!uble y); '!uble get2(); '!uble getTheta(); -!i' set!lar('!uble r. '!uble theta);

'ata Abstraction



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)

!ncrete Hehicle

public interace Hehicle { '!uble get*uelTanFapacity9nall!ns(); '!uble getall!ns,as!line();

'ata Abstraction



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)

Abstract Hehicle

public interace Hehicle { '!uble getercent*uel2emaining();

'ata Abstraction



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)

77 !b:ects hi'e their 'ata behin' abstracti!ns an'77 e"p!se uncti!ns that !perate !n that 'ata

77 'ata structure e"p!se their 'ata an'77 ha-e n! meaningul uncti!ns

'ata


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Error *andling


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g

i ('eleteage(page) == B@,?) { i (registry&'elete2eerence(page&name) == B@,?) { i (c!nig?eys&'elete?ey(page&name&maFe?ey()) == B@,?) l!gger&l!g(6page 'elete'6); else {

l!gger&l!g(6c!nig?ey n!t 'elete'6); else { l!gger&l!g(6'elete2eerence r!m registry aile'6); else {

l!gger&l!g(6'elete aile'6); return B@B22,2;

0re#er 9-ceptions to Returning 9rror Co"es

Error *andling


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g

try { 'eleteage(page); registry&'elete2eerence(page&name); c!nig?eys&'elete?ey(page&name&maFe?ey());

catch (B"cepti!n e) { l!gger&l!g(e&getEessage());

0re#er 9-ceptions to Returning 9rror Co"es

Error *andling


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public -!i' 'elete(age page) { try { 'eleteageAn'All2eerences(page); catch (B"cepti!n e) { l!gBrr!r(e);

pri-ate -!i' 'eleteageAn'All2eerences(age page) thr!ws B"cepti 'eleteage(page); registry&'elete2eerence(page&name); c!nig?eys&'elete?ey(page&name&maFe?ey());

pri-ate -!i' l!gBrr!r(B"cepti!n e) { l!gger&l!g(e&getEessage());

9-tract )r!


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Error *andling


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try { EealB"penses e"penses = e"pense2ep!rtA, &getEeals(empl!yee&get9()); m@t!tal 0= e"penses&getT!tal(); catch(EealB"pensesC!t*!un' e) {

m@t!tal 0= getEealeriem();

'e#ine t$e /ormal *low

Error *andling


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EealB"penses e"penses = e"pense2ep!rtA, &getEeals(empl!yee&get9());m@t!tal 0= e"penses&getT!tal();

'e#ine t$e /ormal *low

Error *andling


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List empl!yees = getBmpl!yees();i (empl!yees G= null) { !r(Bmpl!yee e # empl!yees) { t!talay 0= e&getay();

'on4t Return /ull

Error *andling


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List empl!yees = getBmpl!yees(); !r(Bmpl!yee e # empl!yees) { t!talay 0= e&getay();

public List getBmpl!yees() { i( && there are n! empl!yees && ) return !llecti!ns&emptyList();

'on4t Return /ull

Error *andling


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public '!uble "r!:ecti!n(!int p1. !int p/) { return (p/&" p1&") 8 1&;

public '!uble "r!:ecti!n(!int p1. !int p/) { i (p1 == null \\ p/ == null) { thr!w 9n-ali'ArgumentB"cepti!n (69n-ali' argument !r Eetricsalculat!r&"r!:ecti!n return (p/&" p1&") 8 1&;

'on4t 0ass /ull

+nit Tests


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77 irst law77 y!u may n!t write pr!'ucti!n c!'e until77 y!u ha-e written a ailing unit test

77 sec!n' law

77 y!u may n!t write m!re ! a unit test77 than is suicient t! ail. an' n!t c!mpiling is ailin

77 thir' law77 y!u may n!t write m!re pr!'ucti!n c!'e77 than is suicient t! pass the currently ailing test

)$e )$ree 6aws o# )''


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+nit Tests


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77 tests c!me t! a single c!nclusi!n77 that is 5uicF an' easy t! un'erstan'3ne Assert per )est

Single Concept per )est77 the best rule is that y!u sh!ul'77 minimi4e the number ! asserts per c!ncept an'77 test :ust !ne c!ncept per test uncti!n

+nit Tests


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77 *ast77 9n'epen'ent77 2epeatable77 3elS-ali'ating77 Timely

*.I.R.S.).


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Classes


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77 a class !r m!'ule sh!ul' ha-e !ne. an' !nly !ne.77 reas!n t! change

77 32 is !ne ! the m!re imp!rtant c!ncept in ,, 'esign

)$e Single Responsibilit! 0rinciple SR0

Co$esion77 maintaining c!hesi!n results in many small classes

Emergence


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Simple 'esign Rule 1= Runs All t$e )estsSimple 'esign Rules 2= /o 'uplication

Simple 'esign Rules >= 9-pressi(eSimple 'esign Rules ?= Minimal Classes an" Met$o"s


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