面向对象程序设计MultipleChoice_3

Multiple Choice Quiz 3 1 Which of the following statements about constructors in Java is true a A constructor must be defined as public b A class can define more than one constructor c A constructor must be defined as static d A class must define at least one constructor 2 Which is the Java keyword used to denote a class method a class b private c final d static 3 If a class contains a constructor that constructor will be invoked a once the first time an object of that class is instantiated b each time an object of that class is instantiated c once at the beginning of any program that uses that class d each time an object of that class goes out of scope 4 Which of the following statements about class variables in Java is not true a All objects have their own copy of the class variable defined in the instantiated class b Non static methods in a class can access the class variable defined in the same 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 5 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 non default followed by the line of text default c The line of text default followed by the line of text non default d The line of text non default 6 Which of the following categorizations can be applied to both the data fields and the methods in a Java class a default and non default b native and non native c abstract and non abstract d static and non static 7 From within a child class its parent class is referred to via the keyword a parent b base c super d this 8 Which is a Java access modifier used to designate that a particular data field will not be inherited by a subclass a default b private c protected d final 9 When a subclass defines an instance method with the same return type and signature as a method in its parent the parent s method is said to be a private b overloaded c hidden d overridden 10 Consider the following Java class definitions public class Object1 protected String d return Hi public class Object2 extends Object1 protected String d return super d Which of the following statements is are true regarding the definitions Class Object2 inherits from class Object1 Class Object2 overrides method d Method d returns equivalent results when executed from either class a I and II only b III only c I and III only d I II and III 11 What is used to indicate that a method does not return a value a the keyword void b the name of the class to which it belongs c the keyword static d the omission of the return type 12 The return type for a method that returns nothing to its caller is a false b not specified in the method definition c void d null 13 The term class variable is a synonym for a an instance variable b a private data field c a read only variable d a static data field 14 If the method int sum int a int b is defined in a Java class C which