软件学院_面向对象程序设计_-2009(2)期末b卷复习进程

软件学院_面向对象程序设计_2008-2009(2)期末B卷华南农业大学期末考试试卷（B卷）2008-2009学年第2学期考试科目：面向对象程序设计考试类型：（闭卷）考试时间：120分钟学号________________姓名______________年级专业____________________一、选择题（30分）说明：每题2分，只有1个正确答案，请将正确答案填写在下面表格中。

1．Which of the following statements is correct about Java packages?A. A package may contain unlimited number of nested sub-packages.B. A package is a collection of related Java source program.C. Using the import statement can include all the classes into the current program from a specified package and its sub-packages.D. If there is no package statement used, the current class will not be in any package. 2．Which one is the wrong statement about Java constructors?A. The name of a constructor must be the same as its class’s name.B. A constructor has no return value and can not be modified by void.C. A constructor of the parent class can not be inherited by its sub-classes.D. All constructors must be modified by public.3．Giving the code bellow:class Test{private int m;public static void fun() { /* some code... */ }}How to make the member variable m accessible for method fun()?A. change "private int m" to "protected int m"收集于网络，如有侵权请联系管理员删除B. change "private int m" to "public int m"C. change "private int m" to "static int m"D. change "private int m" to "int m"4．Which of the following functions is an overloading function of "public void example(){...}"?A. public void example(){...}B. public int example(){...}C. public void example2(){...}D. public int example(int m, float f){...}5．In Java, a class may have many different methods with the same name. The number, type, sequences of arguments in these methods are different, and the return value can be different as well. What do we call this feature in terms ofobject-oriented programming?A. HidingB. OverridingC. OverloadingD. This feature is not supported in Java 6．How to execute the following program?public class Test{public static void main(String args[]) {System.out.println(args[0]);}}A. java Test.classB. java TestC. java Test aStringD. javac Test7．If a container has been resized, which of the following layout manager did not change the internal components' size?A. CardLayoutB. FlowLayoutC. BorderLayoutD. GridLayout8．Which is the right statement about exception handling?A. In java, all exceptions are necessary to be caught and handled.B. The “catch”statement catches exception by type-matching.C. In the “try-catch-finally” structure, the program will exit after exception handling.D. Exception is a kind of errors, and it should be absolutely avoided in programs. 9．The following statements are about type-casting, which one is correct?A. A reference variable of a class can only be assigned to an object of its first level sub-收集于网络，如有侵权请联系管理员删除classes of this class.B. An object can not be casted to the type of another class which has no inheritance relationship with the object’s original class.C. A child class’s reference variable can be assigned to an object of its parent class.D. There is only explicit casting, but no implicit casting.10．Both class Teacher and Student are the sub-classes of Person.Person p; Teacher t; Student s; // assume p, t and s are not nullif(t instanceof Person) { s = (Student)t; }Which statement about the last line of expression is correct?A. A new Student object will be created.B. The type-casting is correct.C. The expression is incorrect.D. There is no syntax error but will generate runtime error.11．According to the code below, which statement is correct?public class Test {static Object o;public static void main(String args[]) {System.out.println(o);}}A. Generates compile error.B. Compiles OK, but has runtime errors.C. Outputs zero.D. Outputs “null”.12．According to the code below, select the statement which is false.String s = "Hello";String s1 = new String("Hello");String s2 = s1.intern();String s3 = "Hello";A. s1 == sB. s2 == sC. s == s3D. s2 == s313．The array definition code is given below, which statement is correct?String[][] s = new String[10][];A. The definition of array s is illegal in syntax.B. s is a 10×10 two-dimensional array.C. All elements in s are "".D. s is an array of ten arrays.14．Which is the correct output according to the program given bellow?public static void main(String[] args){收集于网络，如有侵权请联系管理员删除Scanner scanner = new Scanner("this is one that is two");eDelimiter(" is"); // there is a space before "is"while(scanner.hasNext()) {System.out.print(scanner.next());}}A. this one that twoB. th one that twoC. thone that twoD. this is one that is two15． The file “empty.txt” does not exist before, what its content will be after executing the following code.public static void main(String[] args) throws FileNotFoundException {PrintWriter pr = new PrintWriter(new File("empty.txt"));pr.print("one\ttwo");pr.append("\n1\t2");pr.close();}A. one twoB. one\ttwo1 21\t2C. one\ttwo\n1\t2D. one two 1 2二、改错题（20分）说明：写出每段代码的错误原因并改正错误，每小题4分，说明原因和改正各2分。