浙大网新 中研软件 面试 笔试.doc

选择题 1: Consider the class hierarchy shown below: - class FourWheeler implements DrivingUtilities class Car extends FourWheeler class Truck extends FourWheeler class Bus extends FourWheeler class Crane extends FourWheeler - Consider the following code below: 1.DrivingUtilities du; 2.FourWheeler fw; 3.Truck myTruck = new Truck(); 4.du = (DrivingUtilities)myTruck; 5.fw = new Crane(); 6.fw = du; Which of the statements below are true? Choices: A.Line 4 will not compile because an interface cannot refer to an object. B.The code will compile and run. C.The code will not compile without an explicit cast at line 6, because going down the hierarchy without casting is not allowed. D.The code will compile if we put an explicit cast at line 6 but will throw an exception at runtime. 2:A class design requires that a member variable should be accessible only by same package, which modifer word should be used? A.protected B.public C.no modifer D.private 3: Whatistheresultwhenyoucompileandrunthefollowingcode? publicclassThrowsDemo staticvoidthrowMethod() System.out.println(InsidethrowMethod.); thrownewIllegalAccessException(demo); publicstaticvoidmain(Stringargs) try throwMethod(); catch(IllegalAccessExceptione) System.out.println(Caught+e); Choices:What is the result when you compile and run the following code? public class ThrowsDemo static void throwMethod() System.out.println(Inside throwMethod.); throw new IllegalAccessException(demo); public static void main(String args) try throwMethod(); catch (IllegalAccessException e) System.out.println(Caught + e); Choices:A.Compilation error B.Runtime error C.Compile successfully, nothing is printed. D.Inside throwMethod. followed by caught:java.lang.IllegalAccessExcption: demo 4: Inthefollowingcode,whichistheearlieststatement,wheretheobjectoriginallyheldine,maybegarbagecollected: 1.publicclassTest 2.publicstaticvoidmain(Stringargs) 3.Employeee=newEmployee(Bob,48); 4.e.calculatePay(); 5.System.out.println(e.printDetails(); 6.e=null; 7.e=newEmployee(Denise,36); 8.e.calculatePay(); 9.System.out.println(e.printDetails(); 10. 11. OnlyOne:In the following code, which is the earliest statement, where the object originally held in e, may be garbage collected: 1.public class Test 2. public static void main (String args ) 3. Employee e = new Employee(Bob, 48); 4. e.calculatePay(); 5. System.out.println(e.printDetails(); 6. e = null; 7. e = new Employee(Denise, 36); 8. e.calculatePay(); 9. System.out.println(e.printDetails(); 10. 11.Only One: A.Line 10 B.Line 11 C.Line 7 D.Line 8 5: 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 10; i+) switch (digit) case x : int j = 0; System.out.println(j); default : int j = 100;System.out.println(j); int i = j; System.out.println(i); Choices:A.100 will be printed 11 times. B.The code will not compile because the variable i cannot be declared twice within the main() method. C.The code will not compile because the variable j cannot be declared twice within the switch statement. D.None of these. 6: 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 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 13: 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 14: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 15:Which statement about the garbage collection mechanism are true? A.Garbage collection require additional programe code in cases where multiple threads are running. B.The programmer can indicate that a reference through a local variable is no longer of interest. C.The programmer has a mechanism that explicity and immediately frees the memory used by Java objects. D.The garbage collection mechanism can free the memory used by Java Object at explection time. 简答题 16:tomcat中，什么是DefaultServlet？他的功能是