北京方正春元科技发展有限公司

选择题 1: Strings=”ExampleString”;Whichoperationisnotlegal?String s=”Example String”;Which operation is not legal?A.int i=s.length(); B.s3=”x”; C.String short_s=s.trim(); D.String t=”root”+s; 2:What is written to the standard output given the following statement:System.out.println(4|7); Select the right answer: A.4 B.5 C.6 D.7 3: Whathappenswhenyoutrytocompileandrunthefollowingprogram? classMystery Strings; publicstaticvoidmain(Stringargs) Mysterym=newMystery(); m.go(); voidMystery() s=”constructor”; voidgo() System.out.println(s); What happens when you try to compile and run the following program?class MysteryString s;public static void main(String args)Mystery m=new Mystery();m.go();void Mystery()s=”constructor”;void go()System.out.println(s);A.this code compliles but throws an exception at runtime B.this code runs but nothing appears in the standard output C.this code runs and “constructor” in the standard output D.this code runs and writes ”null” in the standard output 4:A class design requires that a particular member variable must be accessible for direct access by any subclasses of this class. but otherwise not by classes which are not members of the same package. What should be done to achieve this? A.The variable should be marked public B.The variable should be marked private C.The variable should be marked protected D.The variable should have no special access modifier 5: Whatwillhappenwhenyouattempttocompileandrunthefollowingcode? intOutput=10; booleanb1=false; if(b1=true)&(Output+=10)=20) System.out.println(Weareequal+Output); else System.out.println(Notequal!+Output); Choices: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:A.Compilation error, attempting to perform binary comparison on logical data type B.Compilation and output of We are equal 10. C.Compilation and output of Not equal! 20. D.Compilation and output of Not equal! 10. 6: Whatwillbetheresultofexecutingthefollowingcode? /Filename;SuperclassX.java packagepackageX; publicclassSuperclassX protectedvoidsuperclassMethodX() intsuperclassVarX; /FilenameSubclassY.java 1.packagepackageX.packageY; 2. 3.publicclassSubclassYextendsSuperclassX 4. 5.SuperclassXobjX=newSubclassY(); 6.SubclassYobjY=newSubclassY(); 7.voidsubclassMethodY() 8. 9.objY.superclassMethodX(); 10.inti; 11.i=objY.superclassVarX; 12. 13. Choices:What will be the result of executing the following code? / Filename; SuperclassX.javapackage packageX; public class SuperclassXprotected void superclassMethodX()int superclassVarX; / Filename SubclassY.java1.package packageX.packageY;2.3.public class SubclassY extends SuperclassX4.5.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:A.Compilation error at line 5 B.Compilation error at line 9 C.Runtime exception at line 11 D.None of these 7: Whatwillbetheresultofexecutingthefollowingcode? publicstaticvoidmain(Stringargs) chardigit=a; for(inti=0;i10;i+) switch(digit) casex: intj=0; System.out.println(j); default: intj=100; System.out.println(j); inti=j; System.out.println(i); Choices:What will be the result of executing the following code? public static void main(String args) char digit = a; for (int i = 0; i 4) System.out.println(“Test1”); elseif(x9) System.out.println(“Test2”); else System.out.println(“Test3”); Whichrangeofvaluexwouldproduceofoutput“Test2”?Give the code fragment:if(x4)System.out.println(“Test 1”);else if (x9)System.out.println(“Test 2”);else System.out.println(“Test 3”);Which range of value x would produce of output “Test 2”? A.x4 C.x9 D.None 10: Whatwillhappenwhenyouattempttocompileandrunthefollowingcode? (Assumethatthecodeiscompiledandrunwithassertionsenabled.) publicclassAssertTest publicvoidmethodA(inti) asserti=0:methodB(); System.out.println(i); publicvoidmethodB() System.out.println(Thevaluemustnotbenegative); publicstaticvoidmain(Stringargs) AssertTesttest=newAssertTest(); test.methodA(-10); What will happen when you attempt to compile and run the following code?(Assume that the code is compiled and run with assertions enabled.)public class AssertTestpublic void methodA(int i)assert i = 0 : methodB();System.out.println(i);public void methodB() System.out.println(The value must not be negative);public static void main(String args)AssertTest test = new AssertTest();test.methodA(-10); A.it will print -10 B.it will result in AssertionError showing the message-“the value must not be negative”. C.the code will not compile. D.None of these. 11: ThefollowingcodeisentirecontentsofafilecalledExample.java,causespreciselyoneerrorduringcompilation: classSubClassextendsBaseClass classBaseClass() Stringstr; publicBaseClass() System.out.println(“ok”); publicBaseClass(Strings) str=s; publicclassExample publicvoidmethod() SubClasss=newSubClass(“hello”); BaseClassb=newBaseClass(“world”); Whichlinewouldbecausetheerror?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? A.9 B.10 C.11 D.12 12: Whatresultsfromattemptingtocompileandrunthefollowingcode? publicclassTernary publicstaticvoidmain(Stringargs) inta=5; System.out.println(Valueis-+(a5)?9.9:9); Choices:What results from attempting to compile and run the following code? public class Ternarypublic static void main(String args)int a = 5;System.out.println(Value is - + (a 5) ? 9.9 : 9); Choices:A.prints: Value is - 9 B.Compilation error C. prints: Value is - 5 D.None of these 13:Which declares for native method in a java class corrected? A.public native void method() B.public native void method(); C.public native method(); D.public void native method(); 14:Which code fragments would correctly identify the number of arguments passed via command line to a Java application, exclude the name of the class that is being invoke. A.int count = args.length; B.int count = args.length-1; C.int count=0; while(argscount!=null) count+; D.int count=0;while (!(argscount.equals(“”) count+; 15:Which statements about Java code security are not true? A.The bytecode verifier loads all classes needed for the execution of a program. B.Executing code is performed by the runtime interpreter. C.At runtime the bytecodes are loaded, checked and run in an interpreter. D.The class loader adds security by separating the namespaces for the classes of the local file system from those imported from network sources. 16: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。 17: 1.publicclassX 2.publicobjectm() 3.objecto=newfloat(3.14F); 4.objectoa=newobject1; 5.oa0=o; 6.o=null; 7.oa0=null; 8.returno; 9