java程序员认证模拟题及详细分析

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1、Java程序员认证模拟题及详细分析二.模拟题1.Whichstatementaboutthegarbagecollectionmechanismaretrue?A.Garbagecollectionrequireadditionalprogramecodeincaseswheremultiplethreadsarerunning.B.Theprogrammercanindicatethatareferencethroughalocalvariableisnolongerofinterest.C.Theprogrammerha

2、samechanismthatexplicityandimmediatelyfreesthememoryusedbyJavaobjects.D.ThegarbagecollectionmechanismcanfreethememoryusedbyJavaObjectatexplectiontime.E.Thegarbagecollectionsystemneverreclaimsmemoryfromobjectswhilearestillaccessibletorunninguserthreads.2.Givethefoll

3、owingmethod:1)publicvoidmethod(){2)Stringa,b;3)a=newString(“helloworld”);4)b=newString(“gameover”);5)System.out.println(a+b+”ok”);6)a=null;7)a=b;8)System.out.println(a);9)}Intheabsenceofcompileroptimization,whichistheearliestpointtheobjectareferedisdefinitelyelibil

4、etobegarbagecollection.A.beforeline3B.beforeline5C.beforeline6D.beforeline7E.Beforeline93.Intheclassjava.awt.AWTEvent,whichistheparentclassuponwhichjdk1.1awteventsarebasedthereisamethodcalledgetIDwhichphraseaccuratelydescribesthereturnvalueofthismethod?A.Itisarefer

5、encetotheobjectdirectlyaffectedbythecauseoftheevent.B.Itisanindicationofthenatureofthecauseoftheevent.C.Itisanindicationofthepositionofthemousewhenitcausedtheevent.D.Inthecaseofamouseclick,itisanindicationofthetextunderthemouseatthetimeoftheevent.E.Ittellsthestateo

6、fcertainkeysonthekeybordatthetimeoftheevent.F.Itisanindicationofthetimeatwhichtheeventoccurred.4.Whichstatementaboutlisteneristrue?A.Mostcomponentallowmultiplelistenerstobeadded.B.Ifmultiplelistenerbeaddtoasinglecomponent,theeventonlyaffectedonelistener.C.Component

7、don?tallowmultiplelistenerstobeadd.D.ThelistenermechanismallowsyoutocallanaddXxxxListenermethodasmanytimesasisneeded,specifyingasmanydifferentlistenersasyourdesignrequire.5.Givethefollowingcode:publicclassExample{publicstaticvoidmain(Stringargs[]){intl=0;do{System.

8、out.println(“Doingitforlis:”+l);}while(--l>0)System.out.println(“Finish”);}}Whichwellbeoutput:A.Doingitforlis3B.Doingitforlis1C.Doingitforlis2D.D