杭州翰天网络科技.doc
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选择题
1:
关于垃圾收集的哪些叙述是对的。
A.程序开发者必须自己创建一个线程进行内存释放的工作。
B.垃圾收集将检查并释放不再使用的内存。
C.垃圾收集允许程序开发者明确指定并立即释放该内存。
D.垃圾收集能够在期望的时间释放被java对象使用的内存。
2:
1.String s=”Example String”;Which operation is not legal?
Strings=”ExampleString”;Whichoperationisnotlegal?
A.inti=s.length（）;
B.s[3]=”x”;
C.Stringshort_s=s.trim（）;
D.Stringt=”root”+s;
3:
Whatiswrittentothestandardoutputgiventhefollowingstatement:
System.out.println（4|7）;
Selecttherightanswer:
A.4
B.5
C.6
D.7
4:
Whichdeclaresfornativemethodinajavaclasscorrected?
A.publicnativevoidmethod（）{}
B.publicnativevoidmethod（）;
C.publicnativemethod（）;
D.publicvoidnativemethod（）;
5:
1.What happens when you try to compile and run the following program?
2.class Mystery{
3.String s;
4.public static void main（String[] args）{
5.Mystery m=new Mystery（）;
6.m.go（）;
7.}
8.void Mystery（）{
9.s=”constructor”;
10.}
11.void go（）{
12.System.out.println（s）;
13.}
14.}
Whathappenswhenyoutrytocompileandrunthefollowingprogram?
classMystery{
Strings;
publicstaticvoidmain（String[]args）{
Mysterym=newMystery（）;
m.go（）;
}
voidMystery（）{
s=”constructor”;
}
voidgo（）{
System.out.println（s）;
}
}
A.thiscodecomplilesbutthrowsanexceptionatruntime
B.thiscoderunsbutnothingappearsinthestandardoutput
C.thiscoderunsand“constructor”inthestandardoutput
D.thiscoderunsandwrites”null”inthestandardoutput
6:
publicclassParent{
intchange（）{…}
}
classChildextendsParent{
}
WhichmethodscanbeaddedintoclassChild?
A.publicintchange（）{}
B.abstractintchang（）{}
C.privateintchange（）{}
D.none
7:
1.What will happen when you attempt to compile and run the following code?
2.
3.public class Static
4.
5.{
6.
7.static
8.
9.{
10.
11.int x = 5;
12.
13.}
14.
15.static int x,y;
16.
17.public static void main（String args[]）
18.
19.{
20.
21. x--;
22.
23. myMethod（）;
24.
25. System.out.println（x + y + ++x）;
26.
27.}
28.
29.public static void myMethod（）
30.
31.{
32.
33.y = x++ + ++x;
34.
35.}
36.
37.}
38.
39.Choices:
Whatwillhappenwhenyouattempttocompileandrunthefollowingcode?
publicclassStatic
{
static
{
intx=5;
}
staticintx,y;
publicstaticvoidmain（Stringargs[]）
{
x--;
myMethod（）;
System.out.println（x+y+++x）;
}
publicstaticvoidmyMethod（）
{
y=x+++++x;
}
}
Choices:
A.prints:
2
B.prints:
3
C.prints:
7
D.prints:
8
8:
Aclassdesignrequiresthataparticularmembervariablemustbeaccessiblefordirectaccessbyanysubclassesofthisclass.butotherwisenotbyclasseswhicharenotmembersofthesamepackage.Whatshouldbedonetoachievethis?
A.Thevariableshouldbemarkedpublic
B.Thevariableshouldbemarkedprivate
C.Thevariableshouldbemarkedprotected
D.Thevariableshouldhavenospecialaccessmodifier
9:
1.Give the following code:
2.public class Example{
3.public static void main（String args[] ）{
4.int l=0;
5.do{
6.System.out.println（“Doing it for l is:
”+l）;
7.}while（--l>0）
8.System.out.println（“Finish”）;
9.}
10.}
11.Which well be output:
Givethefollowingcode:
publicclassExample{
publicstaticvoidmain（Stringargs[]）{
intl=0;
do{
System.out.println（“Doingitforlis:
”+l）;
}while（--l>0）
System.out.println（“Finish”）;
}
}
Whichwellbeoutput:
A.Doingitforlis3
B.Doingitforlis1
C.Doingitforlis2
D.Doingitforlis0
10:
假定a和b为int型变量,则执行下述语句组后,b的值为
a=1;
b=10;
do
{
b-=a;
a++;
}while（b--<0）;
A.9
B.-2
C.-1
D.8
11:
WhichfragmentsarenotcorrectinJavasourcefile?
A.packagetestpackage;publicclassTest{//dosomething...}
B.importjava.io.*;packagetestpackage;publicclassTest{//dosomething...}
C.importjava.io.*;classPerson{//dosomething...}publicclassTest{//dosomething...}
D.importjava.io.*;importjava.awt.*;publicclassTest{//dosomething...}
12:
1.Give this class outline:
2.class Example{
3.private int x;
4.//rest of class body…
5.}
6.Assuming that x invoked by the code java Example, which statement can made x be directly accessible in main（） method of Example.java?
Givethisclassoutline:
classExample{
privateintx;
//restofclassbody…
}
AssumingthatxinvokedbythecodejavaExample,whichstatementcanmadexbedirectlyaccessibleinmain（）methodofExample.java?
A.Changeprivateintxtopublicintx
B.changeprivateintxtostaticintx
C.Changeprivateintxtoprotectedintx
D.changeprivateintxtofinalintx
13:
Inth
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