考试教辅javajava选择题java选择.docx
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考试教辅javajava选择题java选择
JAVA选择题
2.欲构造ArrayList类的一个实例，此类继承了List接口，下列哪个方法是正确的
A.ArrayListmyList=newobject（）;B.ListmyList=newArrayList（）;
C.ArrayListmyList=newList（）;D.ListmyList=newList（）;
3.指出下列程序运行的结果。
A.byteb=128;B.Booleanb=null;
C.long=0xfffLD.double=0.9239d
4.指出下列程序运行的结果
publicclassExample{
Stringstr=newString（“good”）;
char[]ch={‘a’,’b’,’c’};
publicstaticvoidmain（Stringargs[]）{
Exampleex=newexample（）;
ex.change（ex.str,ex.ch）;
System.out.print（ex.str=”and”）;
System.out.print（ex.ch）;
}
publicvoidchange（Stringstr,charch[]）{
str=”testok”;
ch[0]=’g’;
}
}
A.goodandabcB.goodandgbc
C.testokandabcD.testokanggbc
5.运行下列程序，会产生什么结果？
publicclassXextendsThreadimplementsRunable{
publicvoidrun（）{
System.out.println（“thisisrun（）”）;
}
publicstaticvoidmain（Stringargs[]）{
Threadt=newThread（newX（））;
t.start（）;
}
}
A.第一行会产生编译错误B.第六行会产生编译错误
C.第六行会产运行错误D.程序会运行和启动
6.哪个关键字可以对对象加互斥锁？
A.transientB.synchronized
C.serializeD.static
7.下列代码哪一行会出错？
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）}
}
8.publicclassparent{
intchange（）{}
}
classChildextendsParent{}
哪些方法可以加入类Child中？
（多选题）
A.publicintchange（）{}B.intchang（inti）{}
C.privateintchange（）{}D.abstractintchang（）
9.Strings=”hello”;
Stringt=”hello”;
charc[]={‘h’,’e’,’l’,’l’,’o’};
下列哪些表达式返回true？
（多选题）
A.s.equals（t）;B.t.equals（c）;
C.s==t;D.t.equals（newString（“hello”））;
10.给出下面代码段：
1）switch（m）
2）{case0:
System.out.println（“case0”）;
3）case1:
System.out.println（“case1”）;break;
4）case2:
5）default:
System.out.println（“default”）;
6）}
下面m的哪些值将引起”default”的输出？
（多选题）
A.0B.1
C.2D.3
11.对于下面代码：
publicclassSample{
longlength;
publicSample（long1）{length=1;}
publicstaticvoidmain（Stringarg[]）{
Samples1,s2,s3;
s1=newSample（21L）;
s2=newSample（21L）;
s3=s2;
longm=21L;
}
}
下列哪些表达式返回值为‘true’?
（多选题）
A.s1==s2;B.s2==s3;
C.m==s1;D.s1.equals（m）
12.给定下面的代码片段：
publicvoidTest（）{
try{
method（）;
System.out.println（“HelloWorld”）;
}catch（ArrayIndexOutOfBoundsExceptione）{
System.out.println（“Exception1”）;
}finally{
System.out.println（“Thankyou!
”）;
}
}
如果函数method正常运行并返回，会显示下面的哪些信息？
A.HelloWorldB.Exception
C.Exception1D.Thankyou!
13.关于session的论述正确的有：
A.一个session可以对应数个用户
B.一个session只能对应一个用户
C.可以手动关闭一个session
D.session如果不手动关闭，会一直存在Server中
14.Whichofthefollowinglineswillcompilewithoutwarningorerror.
1）floatf=1.3;
2）charc="a";
3）byteb=257;
4）booleanb=null;
5）inti=10;
15.Whatwillhappenifyoutrytocompileandrunthefollowingcode
publicclassMyClass{
publicstaticvoidmain（Stringarguments[]）{
amethod（arguments）;
}
publicvoidamethod（String[]arguments）{
System.out.println（arguments）;
System.out.println（arguments[1]）;
}
}
1）errorCan'tmakestaticreferencetovoidamethod.
2）errormethodmainnotcorrect
3）errorarraymustincludeparameter
4）amethodmustbedeclaredwithString
16.Whichofthefollowingwillcompilewithouterror
1）importjava.awt.*;
packageMypackage;
classMyclass{}
2）packageMyPackage;
importjava.awt.*;
classMyClass{}
3）/*Thisisacomment*/
packageMyPackage;
importjava.awt.*;
classMyClass{}
17.Whatwillbeprintedoutifthiscodeisrunwiththefollowingcommandline?
javamyproggoodmorning
publicclassmyprog{
publicstaticvoidmain（Stringargv[]）
{
System.out.println（argv[2]）;
}
}
1）myprog
2）good
3）morning
4）Exceptionraised:
"java.lang.ArrayIndexOutOfBoundsException:
2"
18.Whatwillhappenwhenyoucompileandrunthefollowingcode?
publicclassMyClass{
staticinti;
publicstaticvoidmain（Stringargv[]）{
System.out.println（i）;
}
}
1）ErrorVariableimaynothavebeeninitialized
2）null
3）1
4）0
19.Whatwillhappenifyoutrytocompileandrunthefollowingcode?
publicclassQ{
publicstaticvoidmain（Stringargv[]）{
intanar[]=newint[]{1,2,3};
System.out.println（anar[1]）;
}
}
1）1
2）Erroranarisreferencedbeforeitisinitialized
3）2
4）Error:
sizeofarraymustbedefined
20.Whatwillhappenifyoutrytocompileandrunthefollowingcode?
publicclassQ{
publicstaticvoidmain（Stringargv[]）{
intanar[]=newint[5];
System.out.println（anar[0]）;
}
}
1）Error:
anarisreferencedbeforeitisinitialized
2）null
3）0
4）5
21.Whatwillbetheresultofattemptingtocompileandrunthefollowingcode?
abstractclassMineBase{
abstractvoidamethod（）;
staticinti;
}
publicclassMineextendsMineBase{
publicstaticvoidmain（Stringargv[]）{
int[]ar=newint[5];
for（i=0;iSystem.out.println（ar[i]）;
}
}
1）asequenceof50'swillbeprinted
2）Error:
arisusedbeforeitisinitialized
3）ErrorMinemustbedeclaredabstract
4）IndexOutOfBoundesError
22.Whatwillbeprintedoutifyouattempttocompileandrunthefollowingcode?
inti=1;
switch（i）{
case0:
System.out.println（"zero"）;
break;
case1:
System.out.println（"one"）;
case2:
System.out.println（"two"）;
default:
System.out.println（"default"）;
}
1）one
2）one,default
3）one,two,default
4）default
23.Whichofthefollowinglinesofcodewillcompilewithouterror
1）inti=0;
if（i）{
System.out.println（"Hello"）;
}
2）booleanb=true;
booleanb2=true;
if（b==b2）{
System.out.println（"Sotrue"）;
}
3）inti=1;
intj=2;
if（i==1||j==2）
System.out.println（"OK"）;
4）inti=1;
intj=2;
if（i==1&|j==2）
System.out.println（"OK"）;
24.Whatwillbeoutputifyoutrytocompileandrunthefollowingcode,butthereisnofilecalledHello.txtinthecurrentdirectory?
.
importjava.io.*;
publicclassMine
{
publicstaticvoidmain（Stringargv[]）
{
Minem=newMine（）;
System.out.println（m.amethod（））;
}
publicintamethod（）
{
try
{
FileInputStreamdis
=newFileInputStream（"Hello.txt"）;
}
catch（FileNotFoundExceptionfne）
{
System.out.println（"Nosuchfilefound"）;
return-1;
}
catch（IOExceptionioe）
{}
finally
{
System.out.println（"Doingfinally"）;
}
return0;
}
}
1）Nosuchfilefound
2Nosuchfilefound,-1
3）Nosuchfilefound,Doingfinally,-1
4）0
25.Whichofthefollowingstatementsaretrue?
1）Methodscannotbeoverridentobemoreprivate
2）staticmethodscannotbeoverloaded
3）privatemethodscannotbeoverloaded
4）Anoverloadedmethodcannotthrowexceptionsnotcheckedinthebaseclass
26.Whatwillhappenifyouattempttocompileandrunthefollowingcode?
classBase{}
classSubextendsBase{}
classSub2extendsBase{}
publicclassCEx{
publicstaticvoidmain（Stringargv[]）{
Baseb=newBase（）;
Subs=（Sub）b;
}
}
1）Compileandrunwithouterror
2）CompiletimeException
3）RuntimeException
27.Whichofthefollowingstatementsaretrue?
1）System.out.println（-1>>>2）;willoutputaresultlargerthan10
2）System.out.println（-1>>>2）;willoutputapositivenumber
3）System.out.println（2>>1）;willoutputthenumber1
4）System.out.println（1<<<2）;willoutputthenumber4
28.Whatwillhappenwhenyouattempttocompileandrunthefollowingcode?
publicclassTuxextendsThread{
staticStringsName="vandeleur";
publicstaticvoidmain（Stringargv[]）{
Tuxt=newTux（）;
t.piggy（sName）;
System.out.println（sName）;
}
publicvoidpiggy（StringsName）{
sName=sName+"wiggy";
start（）;
}
publicvoidrun（）{
for（inti=0;i<4;i++）{
sName=sName+""+i;
}
}
}
1）Compiletimeerror
2）Compilationandoutputof"vandeleurwiggy"
3）Compilationandoutputof"vandeleurwiggy0123"
4）Compilationandoutputofeither"vandeleur","vandeleur0","vandeleur01""vandaleur012"or"vandaleur0123"
29.Whatwillbedisplayedwhenyouattempttocompileandrunthefollowingcode
//Codestart
importjava.awt.*;
publicclassButtextendsFrame{
publicstaticvoidmain（Stringargv[]）{
ButtMyBut=newButt（）;
}
Butt（）{
ButtonHelloBut=newButton（"Hello"）;
ButtonByeBut=newButton（"Bye"）;
add（HelloBut）;
add（ByeBut）;
setSize（300,300）;
setVisible（true）;
}
}
//Codeend
1）Twobuttonssidebysideoccupyingalloftheframe,HelloontheleftandByeontheright
2）OnebuttonoccupyingtheentireframesayingHello
3）OnebuttonoccupyingtheentireframesayingBye
4）TwobuttonsatthetopoftheframeonesayingHellotheothersayingBye
30.Whatwillbeoutputbythefollowingcode?
publicclassMyFor{
publicstaticvoidmain（Stringargv[]）{
inti;
intj;
outer:
for（i=1;i<3;i++）
inner:
for（j=1;j<3;j++）{
if（j==2）
continueouter;
System.out.println（"Valuefori="+i+"Valueforj="+j）;
}
}
}
1）Valuefori=1Valueforj=1
2）Valuefori=2Valueforj=1
3）Valuefori=2Valueforj=2
4）Valuefori=3Valueforj=1
31.Whichstatementistrueofthefollowingcode?
publicclassAgg{
publicstaticvoidmain（Stringargv[]）{
Agga=newAgg（）;
a.go（）;
}
publicvoidgo（）{
DSRossds1=newDSRoss（"one"）;
ds1.start（）;
}
}
classDSRossextendsThread{
privateStringsTname="";
DSRoss（Strings）{
sTname=s;
}
publicvoidrun（）{
notwait（）;
System.out.println（"finished"）;
}
publicvoidnotwait（）{
while（true）{
try{
System.out.println（"waiting"）;
wait（）;
}catch（InterruptedExceptionie）{}
System.out.println（sTname）;
notifyAll（）;
}
}
}
1）Itwillcauseacompiletimeerror
2）Compilationandoutputof"waiting"
3）Compilationando
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