Podcast
Questions and Answers
Parent classes are _________ than their child classes.
Parent classes are _________ than their child classes.
Less Specific
Abstract classes differ from other classes in that you _________.
Abstract classes differ from other classes in that you _________.
cannot instantiate objects from them
Abstract classes can contain _________.
Abstract classes can contain _________.
both Abstract and nonabstract methods
An abstract class Product has two subclasses, Perishable and NonPerishable. Which of the following statements is legal?
An abstract class Product has two subclasses, Perishable and NonPerishable. Which of the following statements is legal?
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An abstract class Employee has two subclasses, Permanent and Temporary. Before you can instantiate these objects, which of the following statements must be true?
An abstract class Employee has two subclasses, Permanent and Temporary. Before you can instantiate these objects, which of the following statements must be true?
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When you create a superclass and one or more subclasses, each object of the subclass _________ superclass object.
When you create a superclass and one or more subclasses, each object of the subclass _________ superclass object.
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Which of the following statements is true?
Which of the following statements is true?
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When you create a _________ in Java, you create a variable name in which you can hold the memory address of an object.
When you create a _________ in Java, you create a variable name in which you can hold the memory address of an object.
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An application's ability to select the correct subclass method to execute is known as _________ method binding.
An application's ability to select the correct subclass method to execute is known as _________ method binding.
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Which statement creates an array of five references to an abstract class named Currency?
Which statement creates an array of five references to an abstract class named Currency?
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You _________ override the toString() method in any class you create.
You _________ override the toString() method in any class you create.
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The Object class equals() method takes _________.
The Object class equals() method takes _________.
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Assume the following statement appears in a working Java program: if(thing.equals(anotherThing)) x = 1; You know that _________.
Assume the following statement appears in a working Java program: if(thing.equals(anotherThing)) x = 1; You know that _________.
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The Object class equals() method considers two object references to be equal if they have the same _________.
The Object class equals() method considers two object references to be equal if they have the same _________.
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Java subclasses have the ability to inherit from _________ parent class(es).
Java subclasses have the ability to inherit from _________ parent class(es).
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The alternative to multiple inheritance in Java is known as a(n) _________.
The alternative to multiple inheritance in Java is known as a(n) _________.
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When you create a class that uses an interface, you include the keyword _________ and the interface's name in the class header.
When you create a class that uses an interface, you include the keyword _________ and the interface's name in the class header.
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You can instantiate concrete objects from a(n)
You can instantiate concrete objects from a(n)
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In Java, a class can _________.
In Java, a class can _________.
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When you want to provide some data or methods that subclasses can inherit, but you want the subclasses to override some specific methods, you should write a(n) _________.
When you want to provide some data or methods that subclasses can inherit, but you want the subclasses to override some specific methods, you should write a(n) _________.
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A _____ class is one from which you cannot create any concrete objects, but from which you can inherit.
A _____ class is one from which you cannot create any concrete objects, but from which you can inherit.
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An abstract method has a body.
An abstract method has a body.
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You can indirectly create a reference to a superclass abstract object.
You can indirectly create a reference to a superclass abstract object.
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Only abstract classes can be used to declare class arrays.
Only abstract classes can be used to declare class arrays.
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The Object class is defined in the _____________ package.
The Object class is defined in the _____________ package.
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The Object class_______ method converts an Object into a String...
The Object class_______ method converts an Object into a String...
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Study Notes
Key Concepts in Java Inheritance and Abstract Classes
- Parent classes are less specific than child classes, creating a general to specific hierarchy.
- Abstract classes cannot be instantiated directly; they act as templates for subclasses.
- Abstract classes can contain both abstract (no implementation) and nonabstract methods (with implementation).
Legal Statements and Constructors
- For the abstract class
Productwith subclassesPerishableandNonPerishable, legal instantiation is:NonPerishable myProduct = new NonPerishable(); - For the abstract class
Employee, bothPermanentandTemporarymust implement thesetType()method to be instantiated.
Object Relationships
- Each object of a subclass is considered an instance of the superclass, emphasizing the "is a" relationship.
- Superclasses may contain abstract methods, allowing flexibility for subclasses.
References and Dynamic Binding
- Creating a reference in Java allows holding the memory address of an object.
- Dynamic method binding occurs when an application selects the correct subclass method to execute at runtime.
Array Creation with Abstract Classes
- An array of references to an abstract class can be declared using
Currency[] currencyref = new Currency;.
Method Overriding and Object Comparison
- Any class can override the
toString()method, enabling custom string representation. - The
equals()method in theObjectclass requires one argument and considers two object references equal if they share the same memory address.
Inheritance Constraints
- Java supports single inheritance for subclasses, permitting inheritance from one abstract superclass.
- Interfaces serve as the alternative to multiple inheritance in Java, allowing a class to implement multiple interfaces.
Additional Notes on Abstract Classes and Interfaces
- Use the keyword
implementsto define a class that includes an interface. - Neither abstract classes nor interfaces can be instantiated directly.
- Abstract classes are suitable for providing base functionality with the option for subclasses to override specific methods.
General Facts about Java
- The
Objectclass is located in thejava.langpackage, providing fundamental methods for all Java objects. - Abstract methods do not have a body, whereas concrete classes can have complete implementations.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of Java's abstract classes and inheritance concepts with these flashcards from Chapter 11. Each card presents key terms and definitions to help reinforce your understanding of parent and child classes. Perfect for students looking to solidify their programming skills.
