Java语言程序设计与数据结构 基础篇原书第11版PPT及其他教辅资源04slide.ppt

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1、1Chapter4MathematicalFunctions,Characters,andStrings2MotivationsSupposeyouneedtoestimatetheareaenclosedbyfourcities,giventheGPSlocations(latitudeandlongitude)ofthesecities,asshowninthefollowingdiagram.Howwouldyouwriteaprogramtosolvethisproblem?Youwillbeabletowritesuchaprogramaftercompletingthischapt

2、er.3ObjectivesTosolvemathematicsproblemsbyusingthemethodsintheMathclass(§4.2).Torepresentcharactersusingthechartype(§4.3).ToencodecharactersusingASCIIandUnicode(§4.3.1).Torepresentspecialcharactersusingtheescapesequences(§4.4.2).Tocastanumericvaluetoacharacterandcastacharactertoaninteger(§4.3.3).Toc

3、ompareandtestcharactersusingthestaticmethodsintheCharacterclass(§4.3.4).Tointroduceobjectsandinstancemethods(§4.4).TorepresentstringsusingtheStringobjects(§4.4).Toreturnthestringlengthusingthelength()method(§4.4.1).ToreturnacharacterinthestringusingthecharAt(i)method(§4.4.2).Tousethe+operatortoconca

4、tenatestrings(§4.4.3).Toreadstringsfromtheconsole(§4.4.4).Toreadacharacterfromtheconsole(§4.4.5).TocomparestringsusingtheequalsmethodandthecompareTomethods(§4.4.6).Toobtainsubstrings(§4.4.7).TofindacharacterorasubstringinastringusingtheindexOfmethod(§4.4.8).Toprogramusingcharactersandstrings(GuessBi

5、rthday)(§4.5.1).Toconvertahexadecimalcharactertoadecimalvalue(HexDigit2Dec)(§4.5.2).Torevisethelotteryprogramusingstrings(LotteryUsingStrings)(§4.5.3).ToformatoutputusingtheSystem.out.printfmethod(§4.6).4MathematicalFunctionsJavaprovidesmanyusefulmethodsintheMathclassforperformingcommonmathematicalf

6、unctions.5TheMathClassClassconstants:PIEClassmethods:TrigonometricMethodsExponentMethodsRoundingMethodsmin,max,abs,andrandomMethods6TrigonometricMethodssin(doublea)cos(doublea)tan(doublea)acos(doublea)asin(doublea)atan(doublea)RadianstoRadians(90)Examples:Math.sin(0)returns0.0Math.sin(Math.PI/6)retu

7、rns0.5Math.sin(Math.PI/2)returns1.0Math.cos(0)returns1.0Math.cos(Math.PI/6)returns0.866Math.cos(Math.PI/2)returns07ExponentMethodsexp(doublea)Returnseraisedtothepowerofa.log(doublea)Returnsthenaturall