大数据基础技能试题与答案

..Java基础1.Whichofthefollowingwillcompilecorrectly?A>floatf=10f;B>floatf=10.1;C>floatf=10.1f;D>byteb=10b;2.WhichdeclarationsofidentifiersarelegalA.$personsB.TwoUsersC.*pointD.thisE._endline3.WhichstatementofassigningalongtypevariabletoahexadecimalvalueiscorrectA.longnumber=345L;B.longnumber=0345;C.longnumber=0345L;D.longnumber=0x345L4.WhichofthefollowingfragmentsmightcauseerrorsA.Strings="Gonewiththewind";Stringt="good";Stringk=s+t;B.Strings="Gonewiththewind";Stringt;t=s[3]+"one";C.Strings="Gonewiththewind";Stringstandard=s.toUpperCase<>;D.Strings="homedirectory";Stringt=s-"directory";5.Whicharesyntacticallyvalidstatementat//pointxclassPerson{privateinta;publicintchange<intm>{returnm;}}publicclassTeacherextendsPerson{publicintb;publicstaticvoidmain<Stringarg[]>{Personp=newPerson<>;Teachert=newTeacher<>;inti;//pointx}}A.i=m;B.i=b;C.i=p.a;D.i=p.change<30>;E.i=t.b.6.Whichlayoutmanagerisusedwhentheframeisresizedthebuttons'spositionintheFramemightbechangedA.BorderLayoutB.FlowLayoutC.CardLayoutD.GridLayout7.Giventhefollowingcodefragment:1>publicvoidcreate<>{2}VectormyVect;3}myVect=newVector<>;4}}WhichofthefollowingstatementsaretrueA.Thedeclarationonline2doesnotallocatememoryspaceforthevariablemyVect.B.Thedeclarationonline2allocatesmemoryspaceforareferencetoaVectorobject.C.Thestatementonline2createsanobjectofclassVector.D.Thestatementonline3createsanobjectofclassVector.E.Thestatementonline3allocatesmemoryspaceforanobjectofclassVector8.Whichofthefollowingansweriscorrecttoexpressthevalue8inoctalnumberA.010B.0x10C.08D.0x89.WhicharenotJavakeywordsA.TRUEB.sizeofC.constD.superE.void10.WhichofthefollowingstatementsaretrueA.Theequals<>methoddeterminesifreferencevaluesrefertothesameobject.B.The==operatordeterminesifthecontentsandtypeoftwoseparateobjectsmatch.C.Theequals<>methodreturnstrueonlywhenthecontentsoftwoobjectsmatch.D.TheclassFileoverridesequals<>toreturntrueifthecontentsandtypeoftwoseparateobjectsmatch.11.WhichstatementsaboutinheritancearetrueA.InJavaprogramminglanguageonlyallowssingleinheritance.B.InJavaprogramminglanguageallowsaclasstoimplementonlyoneinterface.C.InJavaprogramminglanguageaclasscannotextendaclassandimplementainterfacetogether.D.InJavaprogramminglanguagesingleinheritancemakescodemorereliable.12.1>classPerson{2}publicvoidprintValue<inti,intj>{/*…*/}3}publicvoidprintValue<inti>{/*...*/}4}}5>publicclassTeacherextendsPerson{6}publicvoidprintValue<>{/*...*/}7}publicvoidprintValue<inti>{/*...*/}8}publicstaticvoidmain<Stringargs[]>{9}Persont=newTeacher<>;10}t.printValue<10>;11}}12}}Whichmethodwillthestatementonline10callA.online2B.online3C.online6D.online713.WhicharenotJavaprimitivetypesA.shortB.BooleanC.unitD.float14、Themethodresume<>isresponsibleforresumingwhichthread'sexecutionA.Thethreadwhichisstoppedbycallingmethodstop<>B.Thethreadwhichisstoppedbycallingmethodsleep<>C.Thethreadwhichisstoppedbycallingmethodwait<>\D.Thethreadwhichisstoppedbycallingmethodsuspend<>15.WhichofthefollowingrangeofintiscorrectA.-2^7–2^7-1B.0–2^32-1C.-2^15–2^15-1D.-2^31–2^31-116.WhichkeywordshouldbeusedtoenableinteractionwiththelockofanobjectTheflagallowsexclusiveaccesstothatobject.A.transientB.synchronizedC.serializeD.static17.Whichisthereturntypeofthemethodmain<>A.intB.voidC.booleanD.static18.Giventhefollowingcode:if<x>0>{System.out.println<"first">;}elseif<x>-3>{System.out.println<"second">;}else{System.out.println<"third">;}Whichrangeofxvaluewouldprintthestring"second"A.x>0B.x>-3C.x<=-3D.x<=0&x>-319、Whichofthefollowingansweriscorrecttoexpressthevalue10inhexadecimalnumberA.0xAB.0x16C.0AD.01620.WhichstatementsaboutthegarbagecollectionaretrueA.Theprogramdevelopermustcreateathreadtoberesponsibleforfreethememory.B.Thegarbagecollectionwillcheckforandfreememorynolongerneeded.C.Thegarbagecollectionallowtheprogramdevelopertoexplicityandimmediatelyfreethememory.D.Thegarbagecollectioncanfreethememoryusedjavaobjectatexpecttime.21、Giventhefollowingcode:1>publicclassTest{2}intm,n;3}publicTest<>{}4}publicTest<inta>{m=a;}5}publicstaticvoidmain<Stringarg[]>{6}Testt1,t2;7}intj,k;8}j=0;k=0;9}t1=newTest<>;10}t2=newTest<j,k>;11}}12}}WhichlinewouldcauseoneerrorduringcompilationA.line3B.line5C.line6D.line1022、Giventheuncompletedcodeofaclass:classPerson{Stringname,department;intage;publicPerson<Stringn>{name=n;}publicPerson<Stringn,inta>{name=n;age=a;}publicPerson<Stringn,Stringd,inta>{//doingthesameastwoargumentsversionofconstructor//includingassignmentname=n,age=adepartment=d;}}Whichexpressioncanbeaddedatthe"doingthesameas..."partoftheconstructorA.Person<n,a>;B.this<Person<n,a>>;C.this<n,a>;D.this<name,age>.23、WhichofthefollowingstatementsaboutvariablesandtheirscopesaretrueA.Instancevariablesaremembervariablesofaclass.B.Instancevariablesaredeclaredwiththestatickeyword.C.Localvariablesdefinedinsideamethodarecreatedwhenthemethodisexecuted.D.Localvariablesmustbeinitializedbeforetheyareused.24、publicvoidtest<>{try{oneMethod<>;System.out.println<"condition1">;}catch<ArrayIndexOutOfBoundsExceptione>{System.out.println<"condition2">;}catch<Exceptione>{System.out.println<"condition3">;}finally{System.out.println<"finally">;}}WhichwilldisplayifoneMethodrunnormallyA.condition1B.condition2C.condition3D.finally25、Giventhefollowingcode:publicclassTest{voidprintValue<intm>{do{System.out.println<"Thevalueis"+m>;}while<--m>10>}publicstaticvoidmain<Stringarg[]>{inti=10;Testt=newTest<>;t.printValue<i>;}}WhichwillbeoutputA.Thevalueis8B.Thevalueis9C.Thevalueis10D.Thevalueis1126、WhichofthefollowingstatementsaboutdeclarationaretrueA.Declarationofprimitivetypessuchasboolean,byteandsoondoesnotallocatememoryspaceforthevariable.B.Declarationofprimitivetypessuchasboolean,byteandsoonallocatesmemoryspaceforthevariable.C.DeclarationofnonprimitivetypessuchasString,Vectorandsoondoesnotallocatememoryspacefortheobject.D.DeclarationofnonprimitivetypessuchasString,Vectoranssoonallocatesmemoryspacefortheobject.27、IntheJavaAPIdocumentationwhichsectionsareincludedinaclassdocumentA.ThedescriptionoftheclassanditspurposeB.AlistofmethodsinitssuperclassC.AlistofmembervariableD.Theclasshierarchy28、Giventhefollowingcode:1>publicvoidmodify<>{2>inti,j,k;3>i=100;4>while<i>0>{5>j=i*2;6>System.out.println<"Thevalueofjis"+j>;7>k=k+1;8>i--;9>}10}}WhichlinemightcauseanerrorduringcompilationA.line4B.line6C.line7D.line829、WhichofthefollowingstatementsaboutvariablesandscopearetrueA.Localvariablesdefinedinsideamethodaredestroyedwhenthemethodisexited.B.Localvariablesarealsocalledautomaticvariables.C.Variablesdefinedoutsideamethodarecreatedwhentheobjectisconstructed.D.Amethodparametervariablecontinuestoexistforaslongastheobjectisneededinwhichthemethodisdefined.30、Aclassdesignrequiresthatamembervariablecannotbeaccessibledirectlyoutsidetheclass.WhichmodifiershouldbeusedtoobtaintheaccesscontrolA.publicB.nomodifierC.protectedD.private31、Giventhefollowingcodefragment:1>Stringstr=null;2>if<<str!=null>&&<str.length<>>10>>{3}System.out.println<"morethan10">;4}}5>elseif<<str!=null>&<str.length<><5>>{6}System.out.println<"lessthan5">;7}}8>else{System.out.println<"end">;}WhichlinewillcauseerrorA.line1B.line2C.line5D.line832、WhichstatementsaboutJavacodesecurityaretrueA.Thebytecodeverifierloadsallclassesneededfortheexecutionofaprogram.B.Executingcodeisperformedbytheruntimeinterpreter.C.Atruntimethebytecodesareloaded,checkedandruninaninterpreter.D.Theclassloaderaddssecuritybyseparatingthenamespacesfortheclassesofthelocalfilesystemfromthoseimportedfromnetworksources.33、Giventhefollowingcode:publicclassPerson{intarr[]=newint[10];publicstaticvoidmain<Stringa[]>{System.out.println<arr[1]>;}}WhichstatementiscorrectA.Whencompilationsomeerrorwilloccur.B.Itiscorrectwhencompilationbutwillcauseerrorwhenrunning.C.Theoutputiszero.D.Theoutputisnull.34、publicclassParent{publicintaddValue<inta,intb>{ints;s=a+b;returns;}}classChildextendsParent{}WhichmethodscanbeaddedintoclassChildA.intaddValue<inta,intb>{//dosomething...}B.publicvoidaddValue<>{//dosomething...}C.publicintaddValue<inta>{//dosomething...}D.publicintaddValue<inta,intb>throwsMyException{//dosomething...}35、WhichstatementsaboutthreadaretrueA.Onceathreadiscreated,itcanstarrunningimmediately.B.Tousethestart<>methodmakesathreadrunnable,butitdoesnotnecessarilystartimmediately.C.Whenathreadstopsrunningbecauseofpre-emptive,itisplacedatthefrontendoftherunnablequeue.D.Athreadmayceasetobereadyforavarietyofreasons.36、Amembervariabledefinedinaclasscanbeaccessedonlybytheclassesinthesamepackage.WhichmodifiershouldbeusedtoobtaintheaccesscontrolA.privateB.nomodifierC.publicD.protected37、ApublicmembervairablecalledMAX_LENGTHwhichisinttype,thevalueofthevariableremainsconstantvalue100.Useashortstatementtodefinethevariable.A.publicintMAX_LENGTH=100;B.finalintMAX_LENGTH=100;C.finalpublicintMAX_LENGTH=100;D.publicfinalintMAX_LENGTH=100.38、Whichexpressionsarecorrecttodeclareanarrayof10StringobjectsA.charstr[];B.charstr[][];C.Stringstr[];D.Stringstr[10];39、WhichfragmentsarecorrectinJavasourcefileA.packagetestpackage;publicclassTest{//dosomething...}B.importjava.io.*;packagetestpackage;publicclassTest{//dosomething...}C.importjava.io.*;classPerson{//dosomething...}publicclassTest{//dosomething...}D.importjava.io.*;importjava.awt.*;publicclassTest{//dosomething...}40：Strings="hello";Stringt="hello";charc[]={'h','e','l','l','o'};WhichreturntrueA.s.equals<t>;B.t.equals<c>;C.s==t;D.t.equals<newString<"hello">>;E.t==c.41.WhichofthefollowingstatementsarelegalA.longl=4990;B.inti=4L;C.floatf=1.1;D.doubled=34.4;E.doublet=0.9F.42、publicclassParent{intchange<>{…}}classChildextendsParent{}WhichmethodscanbeaddedintoclassChildA.publicintchange<>{}B.intchang<inti>{}C.privateintchange<>{}D.abstractintchang<>{}43、classParent{Stringone,two;publicParent<Stringa,Stringb>{one=a;two=b;}ntln<one>;}}publicclassChildextendsParent{publicChild<Stringa,Stringb>{super<a,b>;}publicvoidprint<>{System.out.println<one+"to"+two>;}publicstaticvoidmain<Stringarg[]>{Parentp=newParent<"south","north">;Parentt=newChild<"east","west">;p.print<>;t.print<>;}}WhichofthefollowingiscorrectA.Causeerrorduringcompilation.B.southeastC.southtonortheasttowestD.southtonortheastE.southeasttowest44、Giventheuncompletedmethod:1>2>{success=connect<>3}if<success==-1>{4}thrownewTimedOutException<>;5}}6}}TimedOutExceptionisnotaRuntimeException.Whichcancompletethemethodofdeclarationwhenaddedatline1A.publicvoidmethod<>B.publicvoidmethod<>throwsExceptionC.publicvoidmethod<>throwsTimedOutExceptionD.publicvoidmethod<>throwTimedOutExceptionE.publicthrowTimedOutExceptionvoidmethod<>45、Giventhefollowingcode:1>classParent{2}privateStringname;3}publicParent<>{}4}}5>publicclassChildextendsParent{6}privateStringdepartment;7}publicChild<>{}8}publicStringgetValue<>{returnname;}9>publicstaticvoidmain<Stringarg[]>{10}Parentp=newParent<>;11}}12>}WhichlinewillcauseerrorA.line3B.line6C.line7D.line8E.line1046、Thevariable"result"isboolean.WhichexpressionsarelegalA.result=true;B.if<result>{//dosomething...}C.if<result!=0>{//sosomething...}D.result=147、ClassTeacherandStudentaresubclassofclassPerson.Personp;Teachert;Students;p,tandsareallnon-null.if<tinstanceofPerson>{s=<Student>t;}WhatistheresultofthissentenceA.ItwillconstructaStudentobject.B.Theexpressionislegal.C.Itisillegalatcompilation.D.Itislegalatcompilationbutpossibleillegalatruntime.48、Giventhefollowingclass:publicclassSample{longlength;publicSample<longl>{length=l;}publicstaticvoidmain<Stringarg[]>{Samples1,s2,s3;s1=newSample<21L>;s2=newSample<21L>;s3=s2;longm=21L;}}WhichexpressionreturnstrueA.s1==s2;B.s2==s3;C.m==s1;D.s1.equals<m>.49、WhichclassescanbeusedastheargumentoftheconstructoroftheclassFilterInputStreamA.FilterOutputStreamB.FileC.InputStreamD.RandomAccessFile50、WhichclassescanbeusedastheargumentoftheconstructoroftheclassFileInputStreamA.InputStreamB.FileC.FileOutputStreamD.String51、WhichisnotamethodoftheclassInputStreamA.intread<byte[]>B.voidflush<>C.voidclose<>D.intavailable<>52、Giventhefollowingcode:classPerson{Stringname,department;publicvoidprintValue<>{System.out.println<"nameis"+name>;System.out.println<"departmentis"+department>;}}publicclassTeacherextendsPerson{intsalary;publicvoidprintValue<>{//doingthesameasintheparentmethodprintValue<>//includingprintthevalueofnameanddepartment.System.out.println<"salaryis"+salary>;}}Whichexpressioncanbeaddedatthe"doingthesameas..."partofthemethodprintValue<>A.printValue<>;B.this.printValue<>;C.person.printValue<>;D.super.printValue<>.53.WhichofthefollowingassignmentisnotcorrectA.floatf=11.1;B.doubled=5.3E12;C.doubled=3.14159;D.doubled=3.14D.Linux基础1.Linux文件权限一共10位长度,分成四段,第三段表示的内容是__。A文件类型B文件所有者的权限C文件所有者所在组的权限D其他用户的权限2．在使用mkdir命令创建新的目录时,在其父目录不存在时先创建父目录的选项是__。A-mB-dC-fD–p3.具有很多C语言的功能,又称过滤器的是__。AcshBtcshCawkDsed4.下列文件中,包含了主机名到IP地址的映射关系的文件是：__。A/etc/HOSTNAMEB/etc/hostsC/etc/resolv.confD/etc/networks5.命令可以从文本文件的每一行中截取指定内容的数据。__AcpBddCfmtDcut6．对名为fido的文件用chmod551fido进行了修改,则它的许可权是__。A-rwxr-xr-xB-rwxr--r--C-r--r--r--D-r-xr-x—x7．用ls–al命令列出下面的文件列表,__文件是符号连接文件。A-rw-rw-rw-2hel-susers56Sep0911:05helloB-rwxrwxrwx2hel-susers56Sep0911:05goodbeyCdrwxr--r--1helusers1024Sep1008:10zhangDlrwxr--r--1helusers2024Sep1208:12cheng8．在vi编辑器中的命令模式下,键入__可在光标当前所在行下添加一新行。A<a>;B<o>;C<I>;DA9．在vi编辑器中的命令模式下,重复上一次对编辑的文本进行的操作,可使用__命令。A上箭头B下箭头C<.>;D<*>;10．用命令ls-al显示出文件ff的描述如下所示,由此可知文件ff的类型为__。-rwxr-xr--1rootroot599Cec1017:12ffA普通文件B硬链接C目录D符号链接11．删除文件命令为：__。AmkdirBrmdirCmvDrm12．对文件进行归档的命令为__。AddBcpioCgzipDtar13．改变文件所有者的命令为__。AchmodBtouchCchownDcat14．在给定文件中查找与设定条件相符字符串的命令为：__。AgrepBgzipCfindDsort15．建立一个新文件可以使用的命令为__。AchmodBmoreCcpDtouch16在下列命令中,不能显示文本文件内容的命令是：__。AmoreBlessCtailDjoin17．文件权限读、写、执行的三种标志符号依次是__。ArwxBxrwCrdxDsrw18．在Shell脚本中,用来读取文件内各个域的内容并将其赋值给Shell变量的命令是__。AfoldBjoinCtrDread19．crontab文件由六个域组成,每个域之间用空格分割,其排列如下：__。AMINHOURDAYMONTHYEARCOMMANDBMINHOURDAYMONTHDAYOFWEEKCOMMANDCCOMMANDHOURDAYMONTHDAYOFWEEKDCOMMANDYEARMONTHDAYHOURMIN20．用ftp进行文件传输时,有两种模式：__。AWord和binaryB.txt和WordDocumentCASCII和binaryDASCII和RichTextFormat21．退出交互模式的shell,应键入__。A<Esc>;B^qCexitDquit数据库sql简答题1.用一条SQL查询出每门课目的平均值Table1：namesubjectmark

张三语文81

张三数学75张三英语87

李四语文76

李四数学90李四英语78

王五语文81

王五数学100

王五英语90

2.表student1如下:

自动编号学号姓名课程编号课程名称分数

12005001