选择题1:What will be the result of executing the following code? // Filename; SuperclassX.java package packageX; public class SuperclassX { protected void superclassMethodX() { } int superclassVarX; } // Filename SubclassY.java 1.package packageX.packageY; 2. 3.public class SubclassY extends SuperclassX 4.{ 5.SuperclassX objX = new SubclassY(); 6.SubclassY objY = new SubclassY(); 7.void subclassMethodY() 8.{ 9.objY.superclassMethodX(); 10.int i; 11.i = objY.superclassVarX; 12.} 13.} Choices: Whatwillbetheresultofexecutingthefollowingcode?//Filename;SuperclassX.javapackagepackageX;publicclassSuperclassX{protectedvoidsuperclassMethodX(){}intsuperclassVarX;}//FilenameSubclassY.java1.packagepackageX.packageY;2.3.publicclassSubclassYextendsSuperclassX4.{5.SuperclassXobjX=newSubclassY();6.SubclassYobjY=newSubclassY(); 7.voidsubclassMethodY()8.{9.objY.superclassMethodX();10.inti;11.i=objY.superclassVarX;12.}13.}Choices:A.Compilationerroratline5B.Compilationerroratline9C.Runtimeexceptionatline11D.Noneofthese2:The following code is entire contents of a file called Example.java,causes precisely one error during compilation: class SubClass extends BaseClass{ } class BaseClass(){ String str; public BaseClass(){ System.out.println(“ok”);} public BaseClass(String s){ str=s;}} public class Example{ public void method(){ SubClass s=new SubClass(“hello”); BaseClass b=new BaseClass(“world”); } } Which line would be cause the error? ThefollowingcodeisentirecontentsofafilecalledExample.java,causespreciselyoneerror duringcompilation:classSubClassextendsBaseClass{}classBaseClass(){Stringstr;publicBaseClass(){System.out.println(“ok”);}publicBaseClass(Strings){str=s;}}publicclassExample{publicvoidmethod(){SubClasss=newSubClass(“hello”);BaseClassb=newBaseClass(“world”);}}Whichlinewouldbecausetheerror?A.9B.10C.11D.123:鉴于Java的特点，它最适合的计算环境是A.并行计算环境B.分布式计算环境C.高强度计算环境D.开放式计算环境4:What will be printed when you execute the following code? class X { Y b = new Y(); X() { System.out.print("X"); } } class Y { Y() { System.out.print("Y"); } } public class Z extends X { Y y = new Y(); Z() { System.out.print("Z"); } public static void main(String[] args) { new Z(); } } Choices: Whatwillbeprintedwhenyouexecutethefollowingcode?classX{Yb=newY();X(){System.out.print("X");}}classY{Y(){System.out.print("Y");}}publicclassZextendsX {Yy=newY();Z(){System.out.print("Z");}publicstaticvoidmain(String[]args){newZ();}}Choices:A.ZB.YZC.XYZD.YXYZ5:Given the following class definition: class A{ protected int i; A(int i){ this.i=i; } } which of the following would be a valid inner class for this class? Select valid answer: Giventhefollowingclassdefinition:classA{protectedinti;A(inti){this.i=i;}}whichofthefollowingwouldbeavalidinnerclassforthisclass?Selectvalidanswer:A.classB{}B.classBextendsA{} C.classBextendsA{B(){System.out.println(“i=”+i);}}D.classB{classA{}}6:下述程序代码中有语法错误的行是（ ）。 int i,ia[10],ib[10]; /*第一行*/ for (i=0;i<=9;i++) /*第2行*/ ia[i]=0; /*第3行*/ ib=ia; /*第4行*/ 下述程序代码中有语法错误的行是（）。inti,ia[10],ib[10];/*第一行*/for(i=0;i<=9;i++)/*第2行*/ia[i]=0;/*第3行*/ib=ia;/*第4行*/A.第1行B.第2行C.第3行D.第4行7:Give this class outline: class Example{ private int x; //rest of class body… } 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.ChangeprivateintxtopublicintxB.changeprivateintxtostaticintxC.Changeprivateintxtoprotectedintx D.changeprivateintxtofinalintx8: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.9B.-2C.-1D.89:public class OuterClass { private double d1 = 1.0; //insert code here } You need to insert an inner class declaration at line 3. Which two inner class declarations are valid? publicclassOuterClass{privatedoubled1=1.0;//insertcodehere}Youneedtoinsertaninnerclassdeclarationatline3.Whichtwoinnerclassdeclarationsarevalid?A.classInnerOne{publicstaticdoublemethoda(){returnd1;}}B.publicclassInnerOne{staticdoublemethoda(){returnd1;}}C.privateclassInnerOne{doublemethoda(){returnd1;}}D.staticclassInnerOne{protecteddoublemethoda(){returnd1;}}10:WhicharenotJavakeywords?A.TRUEB.const C.superD.void11:Inthefollowingpiecesofcode,whichonewillcompilewithoutanyerror?A.StringBuffersb1="abcd";B.Booleanb=newBoolean("abcd");C.C:byteb=255;D.floatfl=1.2;12:public class X{ public Object m(){ Object o = new Float(3.14F);//line 3 Object [] oa = new Object[1];//line 4 oa[0] = o;//line 5 o=null;//line 6 return oa[0];//line 7 } } When is the Float object, created in line 3,eligible for garbage collection? publicclassX{publicObjectm(){Objecto=newFloat(3.14F);//line3Object[]oa=newObject[1];//line4oa[0]=o;//line5o=null;//line6 returnoa[0];//line7}}WhenistheFloatobject,createdinline3,eligibleforgarbagecollection?A.justafterline5.B.justafterline6C.justafterline7(thatis,asthemethodreturns)D.neverinthismethod13:Give the following java source fragement: //point x public class Interesting{ //do something } Which statement is correctly Java syntax at point x? Givethefollowingjavasourcefragement://pointxpublicclassInteresting{//dosomething}WhichstatementiscorrectlyJavasyntaxatpointx?A.publicclassMyClass{//dootherthing…}B.staticintPI=3.14C.classMyClass{//dosomething…}D.none14:Whichofthefollowingstatementsarenotlegal?A.longl=4990;B.inti=4L;C.doubled=34.4;D.doublet=0.9F. 15:What will happen when you attempt to compile and run the following code? int Output = 10; boolean b1 = false; if((b1 == true) && ((Output += 10) == 20)) { System.out.println("We are equal " + Output); } else { System.out.println("Not equal! " + Output); } Choices: Whatwillhappenwhenyouattempttocompileandrunthefollowingcode?intOutput=10;booleanb1=false;if((b1==true)&&((Output+=10)==20)){System.out.println("Weareequal"+Output);}else{System.out.println("Notequal!"+Output); }Choices:A.Compilationerror,attemptingtoperformbinarycomparisononlogicaldatatypeB.Compilationandoutputof"Weareequal10".C.Compilationandoutputof"Notequal!20".D.Compilationandoutputof"Notequal!10".16:What will be the result of executing the following code? boolean a = true; boolean b = false; boolean c = true; if (a == true) if (b == true) if (c == true) System.out.println("Some things are true in this world"); else System.out.println("Nothing is true in this world!"); else if (a && (b = c)) System.out.println("It's too confusing to tell what is true and what is false"); else System.out.println("Hey this won't compile"); Choices: Whatwillbetheresultofexecutingthefollowingcode?booleana=true;booleanb=false;booleanc=true;if(a==true)if(b==true)if(c==true)System.out.println("Somethingsaretrueinthisworld");elseSystem.out.println("Nothingistrueinthisworld!");elseif(a&&(b=c))System.out.println("It'stooconfusingtotellwhatistrueandwhatisfalse");elseSystem.out.println("Heythiswon'tcompile");Choices:A.Thecodewon'tcompileB."Somethingsaretrueinthisworld"willbeprintedC."Heythiswon'tcompile"willbeprinted D.Noneofthese17:给出下面的代码片断。。。下面的哪些陈述为错误的? 1) public void create() { 2) Vector myVect; 3) myVect = new Vector(); 4) } 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)}A.第二行的声明不会为变量myVect分配内存空间。B.第二行语句创建一个Vector类对象。C.第三行语句创建一个Vector类对象。D.第三行语句为一个Vector类对象分配内存空间18:Whichstatementaboutlisteneristrue?A.Mostcomponentallowmultiplelistenerstobeadded.B.Ifmultiplelistenerbeaddtoasinglecomponent,theeventonlyaffectedonelistener.C.Componentdon?tallowmultiplelistenerstobeadd.D.none19:Select valid identifier of Java: SelectvalididentifierofJava:A.%passwdB.3d_gameC.$chargeD.this20:Which is the most appropriate code snippet that can be inserted at line 18 in the following code? (Assume that the code is compiled and run with assertions enabled) 1. import java.util.*; 2. 3. public class AssertTest 4. { 5. private HashMap cctld; 6. 7. public AssertTest() 8. { 9. cctld = new HashMap(); 10. cctld.put("in", "India"); 11. cctld.put("uk", "United Kingdom"); 12. cctld.put("au", "Australia"); 13. // more code... 14. } 15. // other methods .... 16. public String getCountry(String countryCode) 17. { 18. // What should be inserted here? 19. String country = (String)cctld.get(countryCode); 20. return country; 21. } 22. } Whichisthemostappropriatecodesnippetthatcanbeinsertedatline18inthefollowingcode?(Assumethatthecodeiscompiledandrunwithassertionsenabled)1.importjava.util.*;2.3.publicclassAssertTest4.{5.privateHashMapcctld;6.7.publicAssertTest()8.{9.cctld=newHashMap();10.cctld.put("in","India");11.cctld.put("uk","UnitedKingdom");12.cctld.put("au","Australia");13.//morecode...14.}15.//othermethods....16.publicStringgetCountry(StringcountryCode)17.{18.//Whatshouldbeinsertedhere?19.Stringcountry=(String)cctld.get(countryCode);20.returncountry; 21.}22.}A.assertcountryCode!=null;B.assertcountryCode!=null:"Countrycodecannotbenull";C.assertcctld!=null:"Nocountrycodedataisavailable";D.assertcctld:"Nocountrycodedataisavailable";21:What is the result when you compile and run the following code? public class Test { public void method() { for(int i = 0; i < 3; i++) { System.out.print(i); } System.out.print(i); } } Choices: Whatistheresultwhenyoucompileandrunthefollowingcode?publicclassTest{ publicvoidmethod(){for(inti=0;i<3;i++){System.out.print(i);}System.out.print(i);}}Choices:A.0122B.0123C.CompilationerrorD.Noneofthese简答题22:struts2中转换器的实现原理？23:Security公司的网络管理工程师Mr.leak最近发现有不少来自公司外部IP的请求，试图非法访问公司内部资源，为了不影响数据访问流程。他不得不写一个高效的程序——一个工作在Ipv4上的防火墙，如果请求来自非授权的ip地址，则将请求丢弃。为了便于管理，通过文本文件IP.TXT来配置授权的IP地址，文件格式为每行（’/n’）一个IP地址（或IP段），范围不超过一个B类。例如：162.105.91.16359.66.105.059.66.105.255211.71.0.0211.71.255.255限制：IP段的起止地址间以空格隔开。文件不超过10万行，内存不超过4M字节。要求：请编写一个程序，读入IP.TXT文件。并从标准输入接受一个IP地址。如果该地址在授权范围内，则在标准输出上打印Y,否则打印N.如果输入为一个空行，程序结束。请给出思路（文字描述），完成代码，分析你采用算法的优劣。请列举测试方法和思路24:你使用hibernate过程中，遇到那些异常？25:列出某文件夹下的所有文件。26:Servlet的基本架构？写出主要方法。 27:class Something { int I; public void doSomething() { System.out.println("I = " + i); } } 代码是否有错？为什么。 classSomething{intI;publicvoiddoSomething(){System.out.println("I="+i);}}代码是否有错？为什么。28:打印一个N*N的方阵，N为每边字符的个数（3〈N〈20），要求最外层为“X”，第二层为“Y”，从第三层起每层依次打印数字0，1，2，3，...例子：当N=5，打印出下面的图形：XXXXXXYYYXXY0YXXYYYXXXXXX29:在hibernate查询中，iterate()和list()方法的异同是？30:求出10到100之间的素数(只能被1和自身整除的数)并以每行一个素数的格式顺序写入文件su.dat。31:找出32位数中是回文数，且其开方为整数的数。
