java工程师面试题

西安三元数码软件有限公司外派JAVA软件工程师笔试题4303返回上级目录选择题1：在软件生命周期中，下列哪个说法是不准确的？软件生命周期分为计划、开发和运行三个阶段在计划阶段要进行问题焉醛和需求分析在开发后期要进行编写代码和软件测试在运行阶段主要是进行软件维护2:publicclassParent(intchange(){...}}classChildextendsParent(}WhichmethodscanbeaddedintoclassChild?r publicintchange()(} abstractintchang()(}rprivateintchange()(}rnone3:Givethefollowingmethod:publicvoidmethod()(Stringa,b;a=newString(“helloworld”)；b=newString(“gameover”)；System.out.println(a+b+”ok”);a=null;

a=b;System.out.println(a);}Intheabsenceofcompileroptimization,whichistheearliestpointtheobjectareferedisdefinitelyelibiletobegarbagecollection.beforeline5beforeline6beforeline7beforeline94:Strings="ExampleString”;Whichoperationisnotlegal?Cinti=s.length();s[3]=”x”；「一 Stringshort_s=s.trim();CStringt="root"+s;5:关于垃圾收集的哪些叙述是对的。程序开发者必须自己创建一个线程进行内存释放的工作。垃圾收集将检查并释放不再使用的内存。垃圾收集允许程序开发者明确指定并立即释放该内存。垃圾收集能够在期望的时间释放被java对象使用的内存。6:Givethefollowingcode:publicclassExample(publicstaticvoidmain(Stringargs[])(intl=0;do(System.out.println("Doingitforlis:”+l);}while(--l>0)System.out.println("Finish”)；

}}WhichwellbeoutputDoingitforlis3rDoingitforlis1CDoingitforlis2CDoingitforlis07:Whichofthefollowingstatementsaretrue?rTheautomaticgarbagecollectionoftheJVMpreventsprogramsfromeverrunningoutofmemoryrAprogramcansuggestthatgarbagecollectionbeperformedandforceitCGarbagecollectionisplatformindependentCAnobjectbecomeseligibleforgarbagecollectionwhenallreferencesdenotingitaresettonull.8:下面关于变量及其范围的陈述哪些是错的。实例变量是类的成员变量。实例变量用关键字static声明。在方法中定义的局部变量在该方法被执行时创建局部变量在使用前必须被初始化。9:Whichisthemostappropriatecodesnippetthatcanbeinsertedatline18inthefollowingcode?2.(Assumethatthecodeiscompiledandrunwithassertionsenabled)4.1.importjava.util.*;.publicclassAssertTest10.

(12.privateHashMapcctld;6.publicAssertTest()18.(20.cctld=newHashMap();22.cctld.put("in”,"India");24.cctld.put("uk”,"UnitedKingdom");26.cctld.put("au”,"Australia");28.//morecode...30.}32.//othermethods34.publicStringgetCountry(StringcountryCode)36.(38.//Whatshouldbeinsertedhere?40.Stringcountry=(String)cctld.get(countryCode);42.returncountry;44.}46.}assertcountryCode!=null;assertcountryCode!=null:"Countrycodecannotbenull";assertcctld!=null:"Nocountrycodedataisavailable";

assertcctld:"Nocountrycodedataisavailable";10：在下述选项时，没有构成死循环的程序是Cinti=100while(1)(i=i%100+1;if(i>100)break;}for(;;);intk=1000;do{++k;}while(k>=10000);rints=36;while(s);--s;11:给出下面的代码片断。。。下面的哪些陈述为错误的？1)publicvoidcreate(){2)VectormyVect;3)myVect=newVector();4)}第二行的声明不会为变量myVect分配内存空间。第二行语句创建一个Vector类对象。第三行语句创建一个Vector类对象。第三行语句为一个Vector类对象分配内存空间12:Aclassdesignrequiresthatamembervariableshouldbeaccessibleonlybysamepackage,whichmodiferwordshouldbeused?CprotectedpublicC-nomodiferprivate13:Givethefollowingjavasourcefragement://pointxpublicclassInteresting{//dosomething}WhichstatementiscorrectlyJavasyntaxatpointx?

publicclassMyClass(//dootherthing...}staticintPI=3.14classMyClass(//dosomething.}Ccnone14:WhichfragmentsarenotcorrectinJavasourcefile?rpackagetestpackage;publicclassTest{//dosomething...}rimportjava.io.*;packagetestpackage;publicclassTest{//dosomething...}「一 .一 r importjava.io.*;classPerson{//dosomething...}publicclassTest{//dosomething...}「…..•….. importjava.io.*;importjava.awt.*;publicclassTest{//dosomething...}15:以下的C程序代码片段运行后C和d的值分别是多少Inta=1,b=2;Intc,d;c=(a&b)&&a;d=(a&&b)&a;TOC\o"1-5"\h\z0,0C0,1c1,0r1,116:Whatwillbetheresultofexecutingthefollowingcode?2.publicstaticvoidmain(Stringargs[])TOC\o"1-5"\h\z{chardigit='a';for(inti=0;i<10;i++){switch(digit){case'x':{intj=0;

System.out.println(j);TOC\o"1-5"\h\z}default:(intj =100;System.out.println(j);}}}inti=j;System.out.println(i);}25.Choices:100willbeprinted11times.「一 Thecodewillnotcompilebecausethevariableicannotbedeclaredtwicewithinthemain()method.CThecodewillnotcompilebecausethevariablejcannotbedeclaredtwicewithintheswitchstatement.CNoneofthese.17:Givethisclassoutline:classExample(privateintx;//restofclassbody…}AssumingthatxinvokedbythecodejavaExample,whichstatementcanmadexbedirectlyaccessibleinmain()methodofExample.java?CChangeprivateintxtopublicintxchangeprivateintxtostaticintx「一 ChangeprivateintxtoprotectedintxCchangeprivateintxtofinalintx18:WhicharenotJavakeywords?

TRUEconstsupervoid19:设有变量说明语句inta=1,b=0;则执行以下程序段的输出结果为()。switch(a){case1:switch(b){case0:printf("**0**");break;case1:printf("**1**");break;}case2:printf("**2**");break;}printf("\n");r**0**c**0****2**C.**0****1****2**C.**0****1****2**D.有语法错误20：软件生命周期的瀑布模型把软件项目分为3个阶段、8个子阶段，以下哪一个是正常的开发顺序？计划阶段、开发阶段、运行阶段设计阶段、开发阶段、编码阶段设计阶段、编码阶段、维护阶段计划阶段、编码阶段、测试阶段21:Whatwillhappenwhenyouattempttocompileandrunthefollowingcode?2.3.classBase

{6.inti=99;8.publicvoidamethod()10.TOC\o"1-5"\h\z{12.System.out.println("Base.amethod()”);14.}16.Base()18.{20.amethod();22.}24.}26.publicclassDerivedextendsBase28.{30.inti=-1;32.33.34.publicstaticvoidmain(Stringargv[])36.{38.Baseb=newDerived();40.System.out.println(b.i);42.b.amethod();44.}46.publicvoidamethod()

48.TOC\o"1-5"\h\z(50