Podcast
Questions and Answers
What does the keyword 'extends' indicate?
What does the keyword 'extends' indicate?
- A class is declared final
- A superclass has multiple subclasses
- A class implements an interface
- A subclass will inherit from a superclass (correct)
What is the Object class in Java?
What is the Object class in Java?
- The superclass of all Java classes (correct)
- A class with no methods
- The first class that is declared in a program
- A class that cannot be inherited
What is class hierarchy?
What is class hierarchy?
A set of classes related by inheritance.
What does 'protected' mean in terms of access modifiers?
What does 'protected' mean in terms of access modifiers?
What is inheritance in object-oriented programming?
What is inheritance in object-oriented programming?
What does the 'super' keyword do?
What does the 'super' keyword do?
Define direct superclass.
Define direct superclass.
What is meant by 'brittle software'?
What is meant by 'brittle software'?
What does it mean to override a method?
What does it mean to override a method?
What is a clone method?
What is a clone method?
Define indirect superclass.
Define indirect superclass.
A subclass can explicitly invoke a constructor of its superclass by using the superclass constructor call syntax-keyword ______ followed by a set of parentheses containing the superclass constructor's arguments.
A subclass can explicitly invoke a constructor of its superclass by using the superclass constructor call syntax-keyword ______ followed by a set of parentheses containing the superclass constructor's arguments.
Every object of a _____ is also an object of that class's _____. However, a _____ object is not an object of any of its _____.
Every object of a _____ is also an object of that class's _____. However, a _____ object is not an object of any of its _____.
In a(n) _____ relationship, an object has a reference to an object of another class as a member.
In a(n) _____ relationship, an object has a reference to an object of another class as a member.
In a(n) _____ relationship, an object of a subclass type may also be treated as an object of the superclass type.
In a(n) _____ relationship, an object of a subclass type may also be treated as an object of the superclass type.
What are standardized reusable components?
What are standardized reusable components?
What does private mean in terms of member access?
What does private mean in terms of member access?
What is the direct superclass of a subclass?
What is the direct superclass of a subclass?
With _____ inheritance, a class is derived from one superclass. Java does not support _____ inheritance.
With _____ inheritance, a class is derived from one superclass. Java does not support _____ inheritance.
A subclass inherits the members of its superclass that are declared with the access specifiers _____ and _____
A subclass inherits the members of its superclass that are declared with the access specifiers _____ and _____
Which class normally overrides the toString method?
Which class normally overrides the toString method?
How does inheritance promote software reusability?
How does inheritance promote software reusability?
Explain protected member access.
Explain protected member access.
Explain the difference between composition and inheritance.
Explain the difference between composition and inheritance.
Explain the initialization process for an object of class BasePlusCommissionEmployee.
Explain the initialization process for an object of class BasePlusCommissionEmployee.
How to invoke a superclass method from a subclass method?
How to invoke a superclass method from a subclass method?
Study Notes
Java Inheritance Concepts
- Inheritance allows a subclass to inherit properties and methods from a superclass, creating a hierarchical relationship.
- The Object class serves as the ultimate superclass for all Java classes.
- Class relationships established through inheritance are termed class hierarchy.
Access Modifiers
- Protected members can be accessed within the defining class and all its subclasses, as well as other classes in the same package.
- Private members remain inaccessible to subclasses, ensuring encapsulation.
- Members declared with public and protected access specifiers are inherited by subclasses.
Keywords in Inheritance
- The extends keyword indicates that a subclass inherits from a particular superclass.
- The super keyword is used to refer to superclass members and to call a superclass constructor.
- When a subclass invokes a constructor of its superclass, it does so with the super keyword followed by the appropriate parameters.
Types of Relationships
- Is-a relationship indicates that a subclass is a specialized type of a superclass.
- Has-a relationship signifies that an object includes a reference to another object as a member.
- Inheritance leads to brittle software, where minor changes in superclasses can disrupt subclass functionality.
Method Overriding and Cloning
- Method override occurs when a subclass defines a method with the same signature as a method in its superclass.
- The clone method is a protected method that creates a copy of the object it is called on.
Composition vs. Inheritance
- Inheritance grants a new class attributes and behaviors from an existing one, allowing for dual treatment as its type and superclass types.
- Composition involves creating a new class from existing classes’ instances, where the new class typically cannot be treated as an instance of the component classes.
Object Initialization
- When creating an object of a derived class, constructors from the superclass are invoked in sequence, starting from the highest ancestor.
- In the BasePlusCommissionEmployee example, constructors are called in a chain from Object to CommissionEmployee, finally reaching BasePlusCommissionEmployee, which initializes additional attributes.
Accessing Superclass Methods
- To invoke a superclass method from an overriding subclass method, use the super keyword.
- If the subclass method does not override the superclass one, simply call the superclass method by its name with the necessary arguments.
Software Design Principles
- Standardized reusable components are a future trend in software construction, paralleling manufacturing practices in industries like automotive.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your understanding of key concepts from Chapter 9 of Scientific Programming. This quiz covers essential terminology relating to class inheritance, object classes, and access modifiers in Java. Flashcards are a great way to reinforce your learning and prepare for exams.
