部分Java真题

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1、1.Whichstatementistrue?A.Ananonymousinnerclassmaybedeclaredasfinal.B.Ananonymousinnerclasscanbedeclaredasprivate.C.Ananonymousinnerclasscanimplementmultipleinterfaces.D.Ananonymousinnerclasscanaccessfinalvariablesinanyenclosingscope.E.Constructionofaninstanceofastaticinnerclassre

2、quiresaninstanceoftheenclosingouterclass.答案是Danonymousinnerclasscannotdeclaredwithanymodifyer.andcanonlyimplementoneinterface2.Whichstatementaboutstaticinnerclassesistrue?A.AnanonymousclasscanbedeclaredasstaticB.AstaticinnerclasscannotbeastaticmemberoftheouterclassC.Astaticinnerc

3、lassdoesnotrequireaninstanceoftheenclosingclassD.Instancemembersofastaticinnerclasscanbereferencedusingtheclassnameofthestaticinnerclass答案是Cbecausestatic,itneedn'tinstanceofenclosingouterclassandit'sinstancememberneedit'sinstance.3.publicclassFoo{publicstaticvoidmain(Stringsgf[])

4、{StringBuffera=newStringBuffer("A");StringBufferb=newStringBuffer("B");operate(a,b);System.out.println(a+","+b);}staticvoidoperate(StringBufferx,StringBuffery){x.append(y);y=x;}}Whatistheresult?A.Thecodecompilesandprints“A.B”.B.Thecodecompilesandprints“A.A”.C.Thecodecompilesandpr

5、ints“B.B”.D.Thecodecompilesandprints“AB.B”.E.Thecodecompilesandprints“AB.AB”.答案是Djava中都是按值传递的，所以a,b还是指向原来的地址空间，经过operate操作后，x更改了该地址空间的值，而y没有.publicclassFoo{publicstaticvoidmain(Stringsgf[]){StringBuffera=newStringBuffer("A");StringBufferb=newStringBuffer("B");operate(a,b);//方法调用完

6、以后，a对象的内容为：AB,b对象的内容为：BSystem.out.println(a+","+b);}staticvoidoperate(StringBufferx,StringBuffery){//对象传递进来以后又分别复制了一个x和y对象x'和y',x'和x指向同一个对象。y'和y指向同一个对象。x.append(y);//所以执行此步操作以后，main中的x对象的内容也变化了。      //因为本来就是指向同一个对象吗！y=x;//执行此步操作以后，main中的y对象的内容没变！  //因为此y费彼y也！}}classValHold{    p

7、ublicinti=10;}publicclassObParm{publicstaticvoidmain(Stringargv[]){    ObParmo=newObParm();    o.amethod();    }    publicvoidamethod(){        inti=99;        ValHoldv=newValHold();        v.i=30;        another(v,i);        System.out.println(v.i);    }//Endofamethod    publicv

8、oidanother(ValHoldv,inti){        i=0;