Virtual method invocation must be defined with the instanceof operator. true or false?
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Introduction to Java Programming, Includes Data Structures, Eleventh Edition, Y. Daniel LiangThis quiz is for students to practice. A large number of additional quiz is available for instructors using Quiz Generator from the Instructor's Resource Website. Videos for Java, Python, and C++ can be found at https://yongdanielliang.github.io/revelvideos.html. Chapter 11 Inheritance and PolymorphismSection 11.2 Superclasses and Subclasses 11.1 Object-oriented programming allows you to derive new classes from existing classes. This is
called ____________. A. encapsulation B. inheritance C. abstraction D. generalization 11.2 Which
of the following statements are true? A. A subclass is a subset of a superclass. B. A subclass is usually extended to contain more functions and more detailed information than its superclass. C. "class A extends B" means A is a subclass of B.
D. "class A extends B" means B is a subclass of A. Section 11.3 Using the super KeywordSection 11.3.1 Calling Superclass Constructors 11.3 Suppose you create a class Square to be a subclass of GeometricObject. Analyze the following code: Square(double length) { A. The program compiles fine, but you cannot create an instance of Square because the constructor does not specify the length of the Square. B. The program has a compile error because
you attempted to invoke the GeometricObject class's constructor illegally. C. The program compiles fine, but it has a runtime error because of invoking the Square class's constructor illegally. 11.4 Analyze the following code:
class B { A. The program has a compile error because A does not have a default constructor. B. The program has a compile error because the default constructor of A invokes the default constructor of B, but B does not have a default
constructor. C. The program would compile fine if you add the following constructor into A: A(String s) { } D. The program would compile fine if you add the following constructor into A: A(String s) { super(s); } 11.5 Analyze the following
code: class A { A(String s) { public void print() { A. The program does not compile because Test does not have a default constructor Test(). B. The program has an implicit default constructor Test(), but it cannot be compiled, because its super
class does not have a default constructor. The program would compile if the constructor in the class A were removed. C. The program would compile if a default constructor A(){ } is added to class A explicitly. D. The program compiles, but it has a runtime error due to the conflict on the method name print. Section 11.3.2 Constructor Chaining 11.6 What is the output of running class C? class B extends A { public class C { A.
Nothing displayed B. "The default constructor of B is invoked" C. "The default constructor of A is invoked" followed by "The default constructor of B is invoked" D. "The default constructor of B is invoked" followed by "The default constructor
of A is invoked" E. "The default constructor of A is invoked" 11.7 Which of the following is incorrect? A. A constructor may be static. B. A constructor may be
private. C. A constructor may invoke a static method. D. A constructor may invoke an overloaded constructor. E. A constructor invokes its superclass no-arg constructor by default if a constructor does not invoke an overloaded constructor or its superclass's constructor.
Section 11.3.3 Calling Superclass Methods 11.8 Which of the statements regarding the super keyword is incorrect? A. You can use super to invoke a super class constructor. B. You can use super to invoke a super class
method. C. You can use super.super.p to invoke a method in superclass's parent class. D. You cannot invoke a method in superclass's parent class. Section 11.4 Overriding Methods 11.9 Analyze the following
code: class A { public
void m(int i) { class B extends A { A. The program has a compile error, because m is overridden with a different signature in B.
B. The program has a compile error, because b.m(5) cannot be invoked since the method m(int) is hidden in B. C. The program has a runtime error on b.i, because i is not accessible from b. D. The method m is not overridden in B. B inherits the method m from A and defines an overloaded
method m in B. 11.10 The getValue() method is overridden in two ways. Which one is correct? class B { class A extends B { II: class B { class A extends B { A. I B. II C. Both I and II D. Neither Section 11.5 Overriding vs. Overloading 11.11 Which of the following statements are true? A. To override a method, the method must be defined in the subclass using the same signature and compatible return type as in its superclass. B. Overloading a method is to provide more than one method with the
same name but with different signatures to distinguish them. C. It is a compile error if two methods differ only in return type in the same class. D. A private method cannot be overridden. If a method defined in a subclass is private in its superclass, the two methods are completely unrelated. E.
A static method cannot be overridden. If a static method defined in the superclass is redefined in a subclass, the method defined in the superclass is hidden. 11.12 Which of the following statements are true? A. A method can be overloaded in the same class.
B. A method can be overridden in the same class. C. If a method overloads another method, these two methods must have the same signature. D. If a method overrides another method, these two methods must have the same signature. E.
A method in a subclass can overload a method in the superclass. 11.13 Analyze the following code: class A { public A() { public void setI(int i) { class B extends A { @Override A. The constructor of class A is not called. B. The constructor of class A is called and it displays "i from A is
7". C. The constructor of class A is called and it displays "i from A is 40". D. The constructor of class A is called and it displays "i from A is 60". 11.14 Analyze the following code: class A { public A() { public void
setI(int i) { class B extends A { @Override A. The constructor of class A is not called. B. The constructor of class A is called and it displays "i from A is 7". C. The constructor of class A is called and it displays "i from A is 40". D.
The constructor of class A is called and it displays "i from A is 60". Section 11.6 The Object Class and Its toString() Method 11.15 Analyze the following code: class A { @Override A. The program cannot be compiled, because System.out.println(a1) is wrong and it should be replaced by System.out.println(a1.toString()); B. When executing System.out.println(a1), the toString() method in the Object class is invoked. C. When executing
System.out.println(a2), the toString() method in the Object class is invoked. D. When executing System.out.println(a1), the toString() method in the A class is invoked. Section 11.7 Polymorphism 11.16 Given the following code, find the compile error. public static void m(Student x) { class GraduateStudent extends Student { class Student extends Person { class Person extends Object { A. m(new GraduateStudent()) causes an error B. m(new Student()) causes an error C. m(new Person()) causes an error D. m(new Object()) causes an error Section 11.8 Dynamic Binding 11.17 What is the output of the following code?
class Student extends Person { class Person { public
void printPerson() { A. Person Person B. Person Student C. Student Student D. Student
Person 11.18 What is the output of the following code? class Student extends Person { class Person { public void printPerson() {
A. Person Person B. Person Student C. Student Student D. Student Person 11.19 Which of the following statements is
false? A. You can always pass an instance of a subclass to a parameter of its superclass type. This feature is known as polymorphism. B. The compiler finds a matching method according to parameter type, number of parameters, and order of the parameters at compile time. C.
A method may be implemented in several subclasses. The Java Virtual Machine dynamically binds the implementation of the method at runtime. D. Dynamic binding can apply to static methods. E. Dynamic binding can apply to instance methods. Section 11.9 Casting Objects and the instanceof Operator 11.20 Which of the following are Java keywords? A. instanceOf B. instanceof C. cast D.
casting 11.21 Assume Cylinder is a subtype of Circle. Analyze the following code: A. The code has a compile error. B.
The code has a runtime error. C. The code is fine. 11.22 Assume Cylinder is a subtype of Circle. Analyze the following code:
A. The code has a compile error. B. The code has a runtime error. C. The code is fine. 11.23 Given the following classes and their objects: C2 c2 = new C2(); Analyze the following statement: c2 = (C2)((C1)c3); A. c3 is cast into c2 successfully. B. You will get a runtime error because you cannot cast objects from sibling classes. C. You will get a runtime error because the Java runtime system cannot perform multiple casting in nested form. D. The statement is correct. 11.24 Given the following code, which of the following expressions evaluates to false? C1 c1 = new C1(); A. c1 instanceof C1 B. c2 instanceof C1 C.
c3 instanceof C1 D. c4 instanceof C2 11.25 Analyze the following code: A. When assigning s to o in Object o = s, a new object is created. B. When casting o to s in String d = (String)o, a new object is created.
C. When casting o to s in String d = (String)o, the contents of o is changed. D. s, o, and d reference the same String object. 11.26 You can assign _________ to a variable of Object[] type. A.
new char[100] B. new int[100] C. new double[100] D. new String[100] E. new java.util.Date[100] Section 11.10 The Object?s equals() Method 11.27 The equals method is defined in the Object class. Which of the following is correct to override it in the String class? A. public boolean equals(String other) B. public boolean equals(Object other)
C. public static boolean equals(String other) D. public static boolean equals(Object other) 11.28 Which of the following statements are true? A. Override the equals(Object) method in the
Object class whenever possible. B. Override the toString() method in the Object class whenever possible. C. A public default no-arg constructor is assumed if no constructors are defined explicitly. D. You should follow standard Java programming style and naming
conventions. Choose informative names for classes, data fields, and methods. 11.29 What is the output of the following code? A. false false B. true true C. false true D.
true false 11.30 What is the output of the following code? A. false false B. true true C. false true D.
true false 11.31 Given two reference variables t1 and t2, if t1 == t2 is true, t1.equals(t2) must be ___________. 11.32 Given two reference variables t1 and t2, if t1.equals(t2) is true, t1 == t2 ___________. A. is always
true B. is always false C. may be true or false 11.33 Analyze the following code. class A { public boolean equals(Object a) {
class A { public boolean equals(A a) { A. Program 1 displays true and Program 2 displays true B. Program 1 displays false and Program 2 displays true C. Program 1 displays true and Program 2 displays false D. Program
1 displays false and Program 2 displays false 11.34 Analyze the following code. class A { public boolean equals(A a) {
class A { public boolean equals(A a) { A. Program 1 displays true and Program 2 displays
true B. Program 1 displays false and Program 2 displays true C. Program 1 displays true and Program 2 displays false D. Program 1 displays false and Program 2 displays false 11.35
Analyze the following code. class A { public
boolean equals(A a) {
class A { public boolean equals(A a) { A. Program 1 displays true and Program 2 displays true B. Program 1 displays false and Program 2 displays true
C. Program 1 displays true and Program 2 displays false D. Program 1 displays false and Program 2 displays false Section 11.11 The ArrayList Class 11.36 You can create an ArrayList using _________.
A. new ArrayList[] B. new ArrayList[100] C. new ArrayList<>() D. ArrayList() 11.37 Invoking _________ removes all
elements in an ArrayList x. A. x.remove() B. x.clean() C. x.delete() D. x.empty() E. x.clear() 11.38 Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following methods will cause the list to become [Beijing, Chicago, Singapore]? A. x.add("Chicago") B. x.add(0, "Chicago") C.
x.add(1, "Chicago") D. x.add(2, "Chicago") 11.39 Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following method will cause the list to become [Beijing]? A. x.remove("Singapore") B. x.remove(0) C. x.remove(1) D. x.remove(2) 11.40 Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following method will cause runtime errors? A. x.get(1) B. x.set(2, "New York"); C. x.get(2) D. x.remove(2) E. x.size() 11.41 Invoking _________ returns the first element in an ArrayList x. A. x.first() B. x.get(0) C. x.get(1) D. x.get() 11.42 Invoking _________ returns the number of the elements in an ArrayList x. A. x.getSize() B. x.getLength(0) C. x.length(1) D.
x.size() 11.43 Analyze the following code:
A. The last line in the code causes a runtime error because there is no element at index 3 in the array list. B. The last line in the code has a compile error because there is no element at index 3 in the array list. C. If you replace the last line by list.add(3, "Hong Kong"), the code
will compile and run fine. D. If you replace the last line by list.add(4, "Hong Kong"), the code will compile and run fine. 11.44 What is the output of the following code? A. true false B. false true C. true true D. false false 11.45 What is the output of the following code? A. true false B. false true C. true true D. false false 11.46 Suppose an ArrayList list contains {"red", "green", "red", "green"}. What is the list after the following code? A. {"red", "green", "red", "green"} B. {"green", "red", "green"} C.
{"green", "green"} D. {"red", "green", "green"} 11.47 Suppose an ArrayList list contains {"red", "red", "green"}. What is the list after the following code? A. {"red", "red", "green"} B. {"red", "green"} C. {"green"} D. {} 11.48 Suppose an ArrayList list contains {"red", "red", "green"}. What is the list after the following code? A. {"red", "red", "green"} B. {"red", "green"} C. {"green"} D. {} 11.49 Suppose an ArrayList list
contains {"red", "red", "green"}. What is the list after the following code? A.
{"red", "red", "green"} B. {"red", "green"} C. {"green"} D. {} 11.50 The output from the following code is __________. A. [New York] B. [New York,
Atlanta] C. [New York, Atlanta, Dallas] D. [New York, Dallas] Section 11.12 Useful Methods for Lists 11.51 Show the output of the following code: A. ["red", "green", "blue", "red"] B. ["red", "green", "blue"] C. ["red", "red", "green", "blue"] D. ["red", "green", "red", "blue"] 11.52 Analyze the following code: A. The code is correct and displays [1, 2, 3].
B. The code is correct and displays [1.0, 2.0, 3.0]. C. The code has a compile error because an integer such as 1 is automatically converted into an Integer object, but the array element type is Double. D. The code has a compile error because asList(array) requires that the array elements
are objects. 11.53 Analyze the following code: A. The code
is correct and displays [1, 2, 3]. B. The code is correct and displays [1.0, 2.0, 3.0]. C. The code has a compile error because an integer such as 1 is automatically converted into an Integer object, but the array element type is Double. D. The code has a compile error
because asList(array) requires that the array elements are objects. 11.54 Analyze the following code: A. The code is correct and displays 3.
B. The code is correct and displays 3.0. C. The code has a compile error on Collections.max(c). c cannot be an array. D. The code has a compile error on double[] c = {1, 2, 3}. 11.55 Analyze the following code: A. The code is correct and displays [3, 5]. B. The code is correct and displays [5, 3].
C. The code has a compile error on Collections.shuffle(c). c cannot be an array. D. The code has a compile error on Integer[] c = {3, 5}. Section 11.14 The protected Data and Methods 11.56 What modifier should you use on a
class so that a class in the same package can access it but a class (including a subclass) in a different package cannot access it? A. public B. private C. protected D. Use the default
modifier. 11.57 What modifier should you use on the members of a class so that they are not accessible to another class in a different package, but are accessible to any subclasses in any package? A. public B. private
C. protected D. Use the default modifier. 11.58 The visibility of these modifiers increases in this order: A. private, protected, none (if no modifier is used), and public.
B. private, none (if no modifier is used), protected, and public. C. none (if no modifier is used), private, protected, and public. D. none (if no modifier is used), protected, private, and public. 11.59 A class design requires that a particular member variable must be accessible 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. E. The variable should be marked private and an accessor method provided. 11.60 Which of the following statements is false? A. A public class can be accessed by a class from a different package. B. A private method cannot be accessed by a class in a different package. C. A protected method can be
accessed by a subclass in a different package. D. A method with no visibility modifier can be accessed by a class in a different package. 11.61 Which statements are most accurate regarding the following classes? class B extends A { A. An object of B contains data fields i, j, k, m. B. An object of B contains data fields j, k, m.
C. An object of B contains data fields j, m. D. An object of B contains data fields k, m. 11.62 Which statements are most accurate regarding the following classes? class B extends A { A. In the class B, an instance method can only access i, j, k, m. B. In the class B, an instance
method can only access j, k, m. C. In the class B, an instance method can only access j, m. D. In the class B, an instance method can only access k, m. Section 11.15 Preventing Extending and Overriding 11.63 Which of the
following classes cannot be extended? A. class A { } B. class A { private A() { }} C. final class A { } D. class A { protected A() { }} What is the correct definition of enumeration or enum?An enumeration is a data type that consists of a set of named values that represent integral constants, known as enumeration constants. An enumeration is also referred to as an enumerated type because you must list (enumerate) each of the values in creating a name for each of them.
Which searching algorithm involves using a low middle and high index value to find the location of a value in a sorted set of data if it exists?Answer: Binary search involves a low, middle and high index value.
Which class is an ordered collection that may contain duplicates?List is an ordered collection and can contain duplicate elements. You can access any element from its index. List is more like array with dynamic length. List is one of the most used Collection type.
Which of the following method adds a key value map to a HashMap?HashMap put() Method in Java
util. HashMap. put() method of HashMap is used to insert a mapping into a map. This means we can insert a specific key and the value it is mapping to into a particular map.
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