四川大学2011面向对象的程序设计

一、单项选择题（本大题共40 小题，每小题1 分，共40 分）提示：在每小题列出的四个备选项中只有一个是符合题目要求的，请将其代码填写在下表中。

错选、多选或未选均无分。

1. A class design requires that a member variable cannot be accessible directly outside the class. Which modifier should be used to obtain the access control?(a). public (b) no modifier (c) protected (d). private2. Which are not Java keywords?(a). static (b) sizeof (c) super (d) void3. After a breakpoint is hit, a debugger is typically used for which of the following tasks?I. Stepping through method calls, line by line II. Examining a stack traceIII. Examining values of variables in the current method(a) I and III only (b) I and II only (c) II only (d) I, II, and III4. Consider the following UML class diagram.According to the diagram, which of the following statements is (are) true?I .ClassB is a specialization of ClassA.II .ClassA is a generalization of ClassC.III .ClassC is involved in a self-containment loop.(a) I and III only (b) II and III only (c) I, II, and III (d) I and II only5. Which of the following statements about static attributes in Java is (are) true?I. Static attributes can be accessed by non-static methods in the same class.II. A static attribute can be accessed even if no instance of the class in which the attribute is definedexists.III. Static attributes can only be accessed by static methods.(a) I only (b) II only (c) I and II only (d) I, II, and III6. Which method must exist in every Java application?(a) main (b) begin (c) init (d) paint7. Consider the following Java program segment.PrintWriter fileOut = new PrintWriter(new FileWriter("output.txt"));If the file output.txt already exists, which of the following events will occur when the program segment is executed?(a) The existing contents of output.txt will be preserved.(b) The existing contents of output.txt will be erased.(c) A FileAlreadyExists exception will be raised.(d) A run-time error will be generated.8. A design pattern is typically used to(a) reduce the number of classes in the design of a program(b) describe a practical solution to a common design problem(c) allow the use of object-orientated concepts in a language that is not object-oriented(d) ensure that code executes at optimal speed during runtime9. An object model describes which of the following?I .Attributes of classesII .Methods of classesIII .Relationships between classes(a) I and II only (b) I, II, and III (c) II and III only (d) I and III only10.Which of the following Java method declarations does not require that the method return a value?(a) private int myMethod(); (b) public void myMethod();(c) public String myMethod(); (d) public void myMethod();11.Which package does not need to be explicitly imported into a Java program?(a) ng (b) java.io (c) java.applet (d) java.awt12.Consider the following Java program segment.String[] str = {"Three","Two","One"};for (int i = 0; i < str.length; ++i) {System.out.println(str[i]+",");}What will be output upon execution of the program segment?(a) Three/Two/One/ (b) One/Two/Three/ (c) One,Two,Three (d) Three,Two,One13.Which of the following statements about class variables in Java is not true?(a) Non-static methods in a class can access the class variable defined in the same class.(b) All objects have their own copy of the class variable defined in the instantiated class.(c) Class variables require the modifier static in the declarations.(d) Class variables do not need the reference to the object of the instantiated class to access them.14.Given the following code, how many tokens will be output?StringTokenizer st = new StringTokenizer("this is a test", "i");while (st.hasMoreTokens()) {stdOut.println(st.nextToken() );}(a) 1 (b) 2 (c) 3 (d) 415.Which of the following is true regarding the controller part in the Model-View-Controller (MVC)paradigm?(a) The controller is the abstract domain knowledge of an application.(b) The controller is the way in which the abstract domain knowledge of an application is presentedto the user.(c) The controller is the list of abstract classes in an application.(d) The controller is the automatic mechanism by which the user interface is displayed and by which events are communicated between the model and the view. 16.How can you force garbage collection of an object?(a) Garbage collection cannot be forced (b) Call System.gc(). (c). Call Runtime.gc().(d) Set all references to the object to new values(null, for example).17.Which of the following is true of the Singleton design pattern?(a) It ensures that the methods of a class are called by only one other class.(b) It ensures that only one instance of a class is created.(c) It describes classes that have only one method.(d) It describes classes that have only one instance variable.18.In singleton classes, the constructor is __________ to ensure that instantiation is controlled througha(n) __________ method.(a) omitted, static (b) private, instance (c) private, static (d) omitted, instance19.An object that contains methods that traverse a vector linearly from start to finish is known as a(n)(a) iterator (b) Exception (c) int (d) loop20.In a UML diagram, a specialization/generalization relationship is characterized by a line betweentwo classes and a _____ next to the _____ class.(a) triangle, generalization (b) triangle, specialization(c) diamond, specialization (d) diamond, generalization21.When a subclass defines an instance method with the same return type and signature as a method inits parent, the parent's method issaid to be(a) overloaded (b) hidden (c) overridden (d) private22.Which of the following streams typically correspond(s) to screen output?I. System.in II. System.out III. System.err(a) III only (b) I, II, and III (c) II and III only (d) II only23.Consider the Java program below.public class Arr{public static void main(String[] args) {int[] a = {1, 2, 3};System.out.println(a[1]);System.out.println(a[3]);}}Which of the following is true about the result of executing the program?(a) The number 2 is printed and a run-time exception terminates execution.(b) The number 2 is printed and there is no abnormal termination.(c) The number 1 is printed and there is no abnormal termination.(d) The number 3 is printed and a run-time exception terminates execution.24.Which of the following statements is (are) true about interfaces in Java?I .Interfaces can extend other interfaces.II .Interfaces can contain data fields.(a) II only (b) I and II (c) None (d) I only25.A Java array that contains n components will be indexed from _____ through _____.(a) 0, n-1 (b) 0, n (c) 1, n (d) 1, n-126.Which of the following methods is (are) provided by java.util.Iterator?I .next, which causes an iterator to return the next item in its iterationII .remove, which can remove an item from a collection associated with an iterator(a) I only (b) II only (c) I and II (d) None27.Consider the following Java program segment.import java.io.*;public class Test {public Test( ) {System.out.println("default");}public Test( int i ) {System.out.println("non-default");}public static void main(String[] args) {Test t = new Test(2);}}Which of the following will be output during execution of the program segment?(a) The line of text "default"(b) The line of text "default" followed by the line of text "non-default"(c) The line of text "non-default" followed by the line of text "default"(d) The line of text "non-default"28.If a file opened for reading does not exist, which of the following events will occur in Java?(a) A NullPointerException will be raised. (b) A run-time error will occur.(c) A FileNotFoundException will be raised. (d) A new file will be created.29.Which of the following identifiers follow(s) Sun's naming conventions for Java constants?I. START_DATE II. Serving_Size III. AnnualFee(a) I, II, and III (b) I only (c) I and II only (d) I and III only30.What will be output when the following Java program segment is executed?ArrayList<String> animals = new ArrayList<String>();animals.add("cat");animals.add("dog");animals.add("dog");for (int i = 0; i < animals.size(); ++i) {if (animals.get(i).equals("dog")) {animals.remove(i);}}System.out.println(animals.size());(a) 3 (b) 2 (c) 1 (d) 031.Which phrase below best describes the relationship between Country and Capital?(a). IS-A (b) HAS-A (c) USES (d). BEHAVES-LIKE32.Which Java keywords can not appear in a class declaration?(a). extends (b) private (c) void (d). abstract33.Which Java technologies most powerfully supports the programming concept of “encapsulation”?(a) Container Classes (b) Access Restriction (c) Garbage Collection (d) Typing 34.What value will be returned by the call m14(5,6)?public static int m14 (int a, int b) {if (a == 0)return 0;elsereturn b + m14(a-1,b);}(a) 1 (b) 11 (c) 30 (d) 12035.When objects are used for parameter passing,(a) the current values of the data attributes of the object are copied.(b) the initial values of the object instantiation information are copied.(c) the memory reference where the object information is stored is copied.(d) a new object of the same class as the parameter object is instantiated.36.Object Oriented Programming is characterized by using(a) encapsulation. (b) inheritance. (c) polymorphism. (d) all of the above.37.If a subclass has the same method identifier as a superclass method,(a) a compile error message will result. (b) a logic error will result.(c) the superclass method will be used. (d) the subclass method will be used.38.How is information passed from the subclass constructor to the superclass constructor?(a) The superclass constructor is automatically called before the subclass constructor.(b) Use the super keyword followed by a parameter list for the superclass.(c) Use the super keyword followed by the superclass identifier.(d) Use the new operator inside the subclass constructor to instantiate the superclass.39.What design pattern is illustrated by the implemention of the JAVA I/O classes?(a) Decorator (b) Stratege (c) Observer (d) Composite40.What is the output of the program below?public class Java1326 {public static void main(String args[]) {int matrix[ ][ ];matrix = new int[3][4];for(int p = 0; p < 3; p++) {for(int q = 0; q < 4; q++)System.out.print(matrix[p][q] + " ");System.out.println();}System.out.println();}}(a) 0 0 0 0 (b) 0 0 0 (c) 0 (d) Compile Error0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0二、Design Pattern（共20 分）。