Introduction to Programming in Java An Interdisciplinary Approach

735 Pages·2007·95.03 MB·English

by  Robert Sedgewick

Introduction
to
Programming in Java
Introduction
to
Programming in Java
An InterdisciplinaryApproach
RobertSedgewick
and
KevinWayne
Princeton University
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Sedgewick,Robert,1946-
IntroductiontoprogramminginJava:aninterdisciplinaryapproach/byRobertSedgewickandKevinWayne.
p.cm.
Includesindex.
ISBN978-0-321-49805-2(alk.paper)
1.Java(Computerprogramlanguage)2.Computerprogramming. I.Wayne,KevinDaniel,1971-II.Title.
QA76.73.J38S4132007
005.13'3-dc22
2007020235
Copyright©2008PearsonEducation,Inc.Allrightsreserved.Nopartofthispublicationmaybereproduced,
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Thebasisfor educationinthe lastmillenniumwas"reading,writing,andarith
metic;" now itisreading, writing, andcomputing. Learning toprogram isan
essential partoftheeducation ofevery student inthesciences andengineering.
Beyonddirectapplications,itisthefirst stepinunderstandingthenatureofcom
puter science's undeniableimpacton themodernworld.Thisbook aimsto teach
programmingto those who need orwant tolearn it,in ascientificcontext.
Our primarygoal isto empower students bysupplying theexperience and
basictools necessarytousecomputationeffectively. Ourapproachistoteach stu
dents thatwriting aprogram isanatural, satisfying, andcreative experience (not
an onerous taskreserved forexperts). We progressively introduce essential con
cepts, embrace classic applications fromapplied mathematics andthesciences to
illustrate theconcepts, andprovide opportunities for students towrite programs
tosolveengagingproblems.
WeusetheJavaprogramminglanguageforalloftheprogramsinthisbook—
werefertoJavaafterprogramminginthetitletoemphasizetheideathatthebook
isaboutfundamental concepts inprogramming, notJavaperse. This bookteaches
basicskillsforcomputationalproblem-solvingthatareapplicableinmanymodern
computing environments, andisaself-contained treatment intended forpeople
withnopreviousexperienceinprogramming.
ThisbookisaninterdisciplinaryapproachtothetraditionalCS1 curriculum,
wherewe highlighttherole ofcomputinginotherdisciplines,frommaterials sci
enceto genomics to astrophysics to network systems. Thisapproach emphasizes
forstudentsthe essential ideathat mathematics, science, engineering, and com
putingareintertwinedinthemodernworld.While itisaCS1 textbookdesigned
foranyfirst-year college studentinterested inmathematics, science, orengineer
ing(includingcomputerscience),thebookalso canbeusedforself-studyorasa
supplementinacoursethatintegratesprogrammingwithanotherfield.
Coverage Thebookisorganizedaroundfourstagesoflearningtoprogram:ba
sic elements,functions, object-oriented programming, andalgorithms (with data
structures).We providethebasicinformation readers needtobuildconfidencein
writingprogramsateachlevelbeforemovingtothenextlevel.Anessentialfeature
ofourapproach istouse example programs thatsolve intriguing problems, sup
portedwith exercises ranging from self-study drills tochallenging problems that
callfor creativesolutions.
Basic elements include variables, assignment statements, built-in types of
data,flowofcontrol(conditionalsandloops),arrays,andinput/output,including
graphicsandsound.
Functionsandmodules are thestudent'sfirstexposureto modular program
ming. We build upon familiarity with mathematical functions to introduce Java
staticmethods,and then consider the implications of programmingwith func
tions, including libraries offunctions andrecursion. We stress thefundamental
ideaofdividingaprogramintocomponentsthatcanbeindependentlydebugged,
maintained,andreused.
Object-orientedprogrammingisourintroductiontodataabstraction.Weem
phasizetheconceptsofadatatype(asetofvaluesandasetofoperationsonthem)
andanobject (anentity thatholds adata-type value) andtheir implementation
usingJava'sclassmechanism.Weteachstudentshowtouse,create,anddesigndata
types. Modularity,encapsulation,andothermodern programmingparadigms are
the central conceptsofthisstage.
Algorithms and data structures combine these modern programming para
digms with classic methods oforganizing and processing data thatremain effec
tive formodern applications. We provide anintroduction to classical algorithms
forsortingandsearchingaswellas fundamental datastructures (includingstacks,
queues,andsymboltables) andtheirapplication,emphasizingtheuseofthescien
tificmethodtounderstandperformancecharacteristicsofimplementations.
Applications inscienceandengineeringare akeyfeature ofthetext.We moti
vateeachprogrammingconceptthatweaddress byexaminingitsimpacton spe
cific applications.We draw examples from applied mathematics, thephysical and
biologicalsciences,andcomputerscienceitself,andincludesimulationofphysical
systems, numerical methods, datavisualization, soundsynthesis, image process
ing,financial simulation,andinformationtechnology.Specificexamplesincludea
treatmentinthefirstchapterofMarkovchains forwebpageranksandcase stud
iesthat addressthe percolationproblem,N-bodysimulation,andthe small-world
VI
phenomenon.Theseapplications are anintegralpartofthetext. Theyengagestu
dentsinthematerial,illustratetheimportanceoftheprogrammingconcepts,and
provide persuasive evidence ofthecritical role playedbycomputation inmodern
scienceand engineering.
Ourprimarygoalistoteachthespecificmechanismsandskillsthat areneed
edtodevelopeffectivesolutionstoanyprogrammingproblem.Weworkwithcom
pleteJavaprogramsandencouragereaderstousethem.Wefocusonprogramming
byindividuals, notlibraryprogramming orprogramming inthelarge (which we
treat brieflyin an appendix).
Use in the Curriculum This book is intended for afirst-year college course
aimed at teaching novices to program in the context of scientific applications.
Taughtfrom thisbook, prospective majors inanyarea ofscience andengineering
willlearntoprograminafamiliar context.Studentscompletingacoursebasedon
thisbookwillbewell-preparedtoapplytheirskills inlatercourses inscience and
engineering andtorecognize when further education incomputer science might
bebeneficial.
Prospectivecomputersciencemajors,inparticular,canbenefitfromlearning
toprograminthecontextofscientificapplications.Acomputerscientistneedsthe
samebasicbackgroundinthescientificmethodandthesameexposuretotherole
ofcomputationinscienceasdoesabiologist,anengineer,oraphysicist.
Indeed, our interdisciplinary approach enables colleges and universities to
teach prospective computerscience majors andprospective majors inotherfields
ofscienceandengineeringinthesamecourse.Wecoverthematerialprescribedby
CS1, but ourfocus onapplications brings life totheconcepts andmotivates stu
dents tolearnthem. Ourinterdisciplinaryapproach exposes studentstoproblems
inmanydifferentdisciplines,helpingthemtomorewiselychooseamajor.
Whateverthespecificmechanism,theuseofthisbookisbestpositionedearly
in the curriculum. First, thispositioning allows usto leverage familiar material
in high school mathematics andscience. Second, students who learnto program
earlyintheircollegecurriculumwillthenbeabletousecomputersmoreeffectively
whenmoving ontocourses intheirspecialty. Like reading andwriting,program
ming iscertainto be an essential skill foranyscientistor engineer. Studentswho
havegraspedtheconceptsinthisbookwillcontinuallydevelopthatskillthrougha
lifetime,reapingthebenefitsofexploitingcomputationtosolveortobetterunder
standthe problemsand projects thatariseintheir chosen field.
VII
Prerequisites Thisbookismeanttobesuitable fortypical science and engi
neeringstudentsintheirfirstyearofcollege.Thatis,wedonotexpectpreparation
beyond what istypically required for other entry-level science andmathematics
courses.
Mathematicalmaturityisimportant.Whilewe donotdwellonmathematicalma
terial,wedo referto themathematicscurriculumthat students havetakeninhigh
school,includingalgebra,geometry,andtrigonometry.Moststudentsinourtarget
audience (thoseintendingtomajorinthesciencesandengineering) automatically
meetthese requirements. Indeed, we take advantage oftheirfamiliarity withthe
basiccurriculumto introducebasicprogrammingconcepts.
Scientificcuriosityisalso anessentialingredient. Scienceandengineeringstudents
bringwiththemasenseoffascinationintheabilityofscientificinquirytohelpex
plainwhatgoesoninnature.Weleveragethispredilectionwithexamplesofsimple
programsthatspeakvolumes aboutthenaturalworld.Wedonotassumeanyspe
cificknowledgebeyondthatprovidedbytypicalhighschoolcoursesinmathemat
ics,physics,biology,orchemistry.
Programming experience isnotnecessary, butalso isnotharmful. Teaching pro
gramming isourprimarygoal, sowe assume nopriorprogramming experience.
Butwritingaprogramtosolveanewproblemisachallengingintellectualtask,so
studentswhohave writtennumerous programs in high schoolcanbenefitfrom
taking anintroductoryprogramming course based onthis book (just as students
whohavewrittennumerousessaysinhighschoolcanbenefitfromanintroductory
writing course incollege). The book cansupport teaching students withvarying
backgroundsbecausetheapplicationsappealtobothnovicesandexpertsalike.
Experience usingacomputerisalso notnecessary,butalso isnotatall aproblem.
College students use computers regularly, tocommunicate withfriends andrela
tives,listentomusic,processphotos,andmanyotheractivities.Therealizationthat
theycanharness thepower oftheirowncomputer in interesting and important
waysisanexcitingandlastinglesson.
Insummary,virtuallyallstudentsinscienceandengineeringarepreparedtotakea
coursebasedon thisbook asapart oftheir first-semestercurriculum.
VIII
Goals What can instructors of upper-level courses in science and engineering
expectofstudentswhohavecompletedacoursebasedon thisbook?
Wecoverthe CS1 curriculum, but anyonewho hastaught an introductory
programming course knows that expectations of instructors in later courses are
typicallyhigh:eachinstructorexpectsallstudentstobefamiliarwiththecomputing
environment and approachthat heorshewantsto use.Aphysicsprofessormight
expectsomestudentstodesignaprogram overtheweekendtorunasimulation; an
engineeringprofessormightexpectotherstudentstobeusingaparticularpackage
to numericallysolvedifferentialequations;or acomputerscienceprofessormight
expectknowledge of the detailsof a particular programming environment. Is it
realistictomeetsuchdiverseexpectations?Shouldtherebeadifferentintroductory
courseforeachsetofstudents? Collegesanduniversities havebeenwrestlingwith
suchquestionssincecomputerscameintowidespread useinthelatterpart ofthe
20thcentury.Ouranswertothemisfoundinthiscommonintroductorytreatment
ofprogramming,which isanalogous tocommonlyacceptedintroductorycourses
in mathematics, physics, biology, andchemistry.An Introduction to Programming
strivesto provide the basicpreparation neededbyallstudents in scienceand en
gineering,whilesendingthe clearmessage that thereismuch more to understand
about computer science than programming. Instructors teaching students who
have studiedfromthisbookcanexpectthattheyhave theknowledge andexperi
encenecessarytoenablethemtoadapttonewcomputationalenvironmentsandto
effectivelyexploitcomputersindiverseapplications.
Whatcanstudentswhohavecompletedacoursebasedon thisbook expectto ac
complish in later courses?
Our messageisthat programming isnot difficultto learn and that harness
ingthe powerofthe computer isrewarding. Studentswhomasterthe material in
this book areprepared to addresscomputationalchallenges whereverthey might
appearlaterintheir careers.Theylearnthat modern programming environments,
such asthe one providedbyJava, help open the door to anycomputationalprob
lem they might encounter later, and they gain the confidence to learn, evaluate,
and useothercomputationaltools.Students interested incomputersciencewillbe
well-prepared to pursue that interest; students in scienceand engineering willbe
readyto integratecomputationinto theirstudies.
IX
Booksite An extensiveamount of information that supplements this text may
befound ontheweb at
http://www.cs.princeton.edu/IntroProgramming
Foreconomy,werefer tothissiteasthebooksitethroughout.It contains material
for instructors, students, and casualreadersof the book. Webrieflydescribethis
materialhere,though,asallwebusersknow,itisbestsurveyedbybrowsing.Witha
fewexceptionstosupporttesting,thematerialisallpubliclyavailable.
One of the most important implicationsof the booksite is that it empow
ers instructors and students to use their own computers to teach and learn the
material. Anyone withacomputerandabrowser canbeginlearningto program
byfollowing afew instructions on thebooksite. Theprocess isno moredifficult
than downloading amediaplayer or asong. As withanywebsite, our booksite is
continuallyevolving.Itisanessentialresourceforeveryonewhoownsthisbook.In
particular,thesupplementalmaterials arecriticaltoourgoalofmakingcomputer
scienceanintegralcomponentoftheeducationofallscientistsandengineers.
For instructors, the booksite contains information about teaching. This in
formationisprimarilyorganized aroundateaching style that wehave developed
over the pastdecade, where we offer two lectures per week to a large audience,
supplementedbytwoclasssessionsperweekwherestudentsmeetinsmallgroups
withinstructorsorteachingassistants.Thebooksitehaspresentationslidesforthe
lectures,whichsetthetone.
Forteachingassistants, thebooksite containsdetailedproblemsetsandpro
grammingprojects,whicharebasedonexercisesfromthebookbutcontainmuch
moredetail.Eachprogrammingassignmentisintendedtoteacharelevantconcept
inthecontextofaninterestingapplicationwhilepresentinganinvitingandengag
ingchallenge to eachstudent.Theprogression of assignments embodies our ap
proachto teachingprogramming.Thebooksitefullyspecifies allthe assignments
and providesdetailed, structuredinformationto helpstudents completethem in
the allottedtime,includingdescriptions ofsuggestedapproachesand outlinesfor
what shouldbetaughtin classsessions.
Forstudents,thebooksitecontainsquickaccesstomuchofthe materialinthe
book, including sourcecode,plusextramaterial to encourage self-learning.Solu
tions are provided for many of the book's exercises, including complete program
code andtest data. There isawealth ofinformationassociated with programming
assignments, includingsuggestedapproaches,checklists,FAQs,and test data.