Question 1

When you show abstract classes and methods in class diagrams, their names appear in ____.

Accepted Answer

Typically, abstract classes and methods are shown in italics in class diagrams to differentiate them from concrete classes and methods. This convention helps in understanding the structure of the code and its implementation.

Question 2

When you create a new subclass in Java, neither the superclass source code nor the superclass ____ is changed.

Accepted Answer

When creating a new subclass in Java, neither the superclass source code nor the superclass bytecode is changed. The subclass is simply adding new functionality or modifying existing functionality of the superclass.

Question 3

Classes, such as the String class, have their own equals() methods that overload the ____ class method.

Accepted Answer

The equals() method in classes like String overloads the equals() method in the Object class, which is the superclass of all Java classes. This allows the String class to provide its own implementation of the equals() method.

Question 4

Which of the following is NOT true regarding abstract methods?

Accepted Answer

Abstract methods are declared in the parent class but have no implementation. They must be implemented by the child classes. However, abstract methods are not inherited by their children. Rather, the child classes must implement the abstract methods themselves.

Question 5

When you create a class and use the implements clause to implement an interface but fail to code one of the interface's methods, the compiler error generated indicates that you must declare your class to be ____.

Accepted Answer

If a class implements an interface but fails to code one of the interface's methods, the class must be declared abstract. This is because the class is not implementing all the abstract methods of the interface, and therefore cannot be instantiated.

Question 6

If Java did not allow you to ____ classes, you would need to create every part of a program from scratch.

Accepted Answer

Without the ability to extend classes, you would not be able to inherit or reuse code from preexisting classes. This would require you to create every aspect of a program from scratch, resulting in a significant amount of redundant and time-consuming code.

Question 7

The Object class equals() method returns a boolean value indicating whether the objects are equal. This equals() method considers two objects to be equal only if they have the same ____________________ .

Accepted Answer

The answer of The Object class equals() method returns a...

Question 8

If you provide an empty method within an abstract class, the method is an abstract method even if you do not explicitly use the keyword ____________________ when defining the method.

Accepted Answer

The answer of If you provide an empty method within...

Question 9

A(n) ____ looks much like a class, except that all of its methods (if any) are implicitly public and abstract.

Accepted Answer

An interface in Java looks much like a class, except that all of its methods (if any) are implicitly public and abstract. It contains only constants, method declarations (without implementations), and default methods. It is used to achieve abstraction and multiple inheritances in Java.

Question 10

If you do not specify a package for a class, it is placed in an unnamed ____ package.

Accepted Answer

When no package is specified for a class, it is placed in the default unnamed package.

Question 11

____ compress the data they store, which reduces the size of archived class files.

Accepted Answer

JAR files compress the data they store, resulting in smaller archived class files.

Question 12

When you create a number of classes that inherit from each other, as well as multiple interfaces that you want to implement with these classes, you often will find it convenient to place these related classes in a(n) ____________________.

Accepted Answer

The answer of When you create a number of classes...

Question 13

The Object class equals() method returns a(n) ____ value indicating whether the objects are equal.

Accepted Answer

The equals() method of Object class returns a boolean value, which is either true or false, indicating whether the objects are equal or not.

Question 14

In other programming languages, such as C++, abstract classes are known as ____________________ classes.

Accepted Answer

The answer of In other programming languages, such as C++,...

Question 15

The capability to inherit from more than one class is called ____.

Accepted Answer

The capability to inherit from more than one class is called multiple inheritance. This allows a class to inherit features and behaviors from multiple parent classes.

Question 16

In the Java programming language, a package or class library is often delivered to users as a(n) ____________________ file.

Accepted Answer

The answer of In the Java programming language, a package...

Question 17

The ____ method is useful in debugging a program because it can be used to display and examine values.

Accepted Answer

The toString() method is used to return a string representation of an object. This string can then be printed or displayed to examine the values of the object and help with debugging. The finalize(), notify(), and equals() methods are not useful for this purpose.

Question 18

Java's Object class contains a public method named ____ that returns an integer representing the hash code.

Accepted Answer

The public method named hashCode() returns an integer representing the hash code of the object, which can be used for hashing in hash tables and similar data structures. The other options are not relevant to the hash code.

Question 19

____ is a calculated number that is used to uniquely identify an object.

Accepted Answer

A hash code is a calculated number used to uniquely identify an object, such as in hashing algorithms used in data structures like hash tables. Method binding refers to the process of associating a method with its implementation, implicit conversion is a type conversion that happens automatically, and ad-hoc polymorphism refers to the ability of a function to take arguments of different types and behave differently depending on the type. None of these choices describe the concept of a hash code.

Question 20

When a class both extends and implements, by convention the ____ clause follows the extends clause in the class header.

Accepted Answer

By convention, the "implements" clause follows the "extends" clause in the class header when a class both extends a superclass and implements an interface.

Quiz 11: Advanced Inheritance Concepts

When you show abstract classes and methods in class diagrams, their names appear in ____.