Question 1

One of the advantages of the linear search is that it does not require its data to be sorted.

Accepted Answer

Linear search can be applied to both sorted and unsorted data, whereas some other search algorithms like binary search require the data to be sorted.

Question 2

It is possible to sort an array of int, float, double or String, but not an array of an Object class such as a CD class.

Accepted Answer

It is possible to sort an array of an Object class such as a CD class by implementing the Comparable or Comparator interface and providing a custom sorting logic.

Question 3

A reference variable can refer to any object created from any class related to it by inheritance.

Accepted Answer

This is true, as long as the reference variable is declared as an object of a parent class or interface that the related classes implement.

Question 4

In order to determine the type that a polymorphic variable refers to, the decision is made
A) by the programmer at the time the program is written
B) by the compiler at compile time
C) by the operating system when the program is loaded into memory
D) by the Java run-time environment at run time
E) by the user at run time

Accepted Answer

The Java run-time environment determines the type that a polymorphic variable refers to at run time through a process called dynamic binding or late binding. This allows for greater flexibility in the code and allows objects of different types to be used interchangeably in certain situations. The programmer does not explicitly determine the type, and it is not determined by the compiler or operating system. The user also does not have control over the type that a polymorphic variable refers to.

Question 5

The fact that the System.out.println() method is able to handle such a wide variety of objects, and print them correctly, is an example of the polymorphic nature of the println() method.

Accepted Answer

The System.out.println() method is able to handle different types of objects and print them correctly. This is an example of polymorphism, which is the ability of a method to take different types of objects and behave differently based on the object's class.

Question 6

The binary search can be used on unsorted data. It will just perform more slowly.

Accepted Answer

Binary search requires sorted data, otherwise it will not work correctly.

Question 7

To swap the 3rd and 4th elements in the int array values, you would do:
values[3] = values[4];
values[4] = values[3];

Accepted Answer

The code provided would not effectively swap the 3rd and 4th elements. To achieve the swap, you would need to temporarily store the value of the 3rd element before overwriting it with the value of the 4th element. The correct code would be:

int temp = values[3];
values[3] = values[4];
values[4] = temp;

Question 8

A GUI control that allows the user to specify a numeric value within a bounded range is a spinner.

Accepted Answer

The answer of A GUI control that allows the user...

Question 9

A polymorphic reference can refer to different types of objects over time.

Accepted Answer

A polymorphic reference can refer to objects of different types at different times during program execution. This is a key feature of polymorphism in object-oriented programming.

Question 10

Code Example Ch 10-1
An int array stores the following values:
 $$\begin{array} { | l | l | l | l | l | l | l | } 
\hline 9 & 4 & 12 & 2 & 6 & 8 & 18 \
\hline
\end{array}$$
-Refer to Code Example Ch 10-1: Which of the following lists of numbers would accurately show the array after the second pass of the selection sort algorithm?
A) 9, 4, 12, 2, 6, 8, 18
B) 2, 4, 9, 6, 12, 8, 18
C) 2, 4, 12, 9, 6, 8, 18
D) 2, 4, 6, 8, 9, 12, 18
E) 2, 4, 9, 12, 6, 8, 18

Accepted Answer

The answer of Code Example Ch 10-1
An int array stores...

Question 11

An interface reference can refer to any object of any class that implements the interface.

Accepted Answer

An interface reference can refer to any object of any class that implements the interface. This is one of the main benefits of using interfaces in object-oriented programming.

Question 12

A variable declared to be of one class can later reference an extended class of that class. This variable is known as
A) protected
B) derivable
C) cloneable
D) polymorphic
E) None of these; a variable declared to be of one class can never reference any other type of class, even an extended class

Accepted Answer

A variable declared as an instance of a class can later reference an extended class of that class if the extended class has an "is-a" relationship with the original class. This is known as polymorphism. It allows for greater flexibility and code reuse in object-oriented programming.

Question 13

The spinner GUI control can allow the user to select values that are either numbers or strings.

Accepted Answer

The spinner control can be used to select values that are either numbers or strings, depending on how it is implemented.

Question 14

If classes C1 and C2 both implement an interface Cint, which has a method whichIsIt, and if C1 c = new C1(); is performed at one point of the program, then a later instruction
c.whichIsIt(); will invoke the whichIsIt method defined in C1.

Accepted Answer

The answer of If classes C1 and C2 both implement...

Question 15

The type of the reference, not the type of the object, is used to determine which version of a method is invoked in a polymorphic reference.

Accepted Answer

In polymorphism, the type of the object, not the reference, determines which version of a method is invoked.

Question 16

Code Example Ch 10-1
An int array stores the following values:
 $$\begin{array} { | l | l | l | l | l | l | l | } 
\hline 9 & 4 & 12 & 2 & 6 & 8 & 18 \
\hline
\end{array}$$
-Refer to Code Example Ch 10-1: Which of the following lists of numbers would accurately show the array after the first pass of the selection sort algorithm?
A) 9, 4, 12, 2, 6, 8, 18
B) 2, 4, 9, 6, 12, 8, 18
C) 2, 4, 12, 9, 6, 8, 18
D) 2, 4, 6, 8, 9, 12, 18
E) 2, 4, 9, 12, 6, 8, 18

Accepted Answer

The answer of Code Example Ch 10-1
An int array stores...

Question 17

What does the following code do? Assume list is an array of int values, temp is some previously initialized int value, and c is an int initialized to 0. for (j = 0; j < list.length; j++)
If (list[j] < temp) c++;
A) It finds the smallest value and stores it in temp.
B) It finds the largest value and stores it in temp.
C) It counts the number of elements equal to the smallest value in list.
D) It counts the number of elements in list that are less than temp.
E) It sorts the values in list to be in ascending order.

Accepted Answer

The code iterates through the array list and checks each element. If the element is less than the value of temp, c is incremented. Therefore, the code is counting the number of elements in list that are less than temp.

Question 18

A method's parameter can be polymorphic, giving the method flexible control of its arguments.

Accepted Answer

Polymorphic parameters allow a method to accept arguments of different types, increasing its flexibility and reusability.

Question 19

Java allows one to create polymorphic references using inheritance and using interfaces.

Accepted Answer

Java allows one to create polymorphic references using inheritance and using interfaces by leveraging the concept of dynamic method dispatch. This allows objects of different classes to be referred to by the same variable, and enables the implementation of polymorphism in Java.

Question 20

An class reference can refer to any object of any class that descends from the class.

Accepted Answer

A class reference variable can hold an object of any class that is a subclass or descendent of the class it belongs to. This is because a subclass inherits all the properties and methods of its parent class.

Quiz 10: Polymorphism