Podcast
Questions and Answers
A polymorphic reference is one that can refer to _______________ type(s) of object(s).
A polymorphic reference is one that can refer to _______________ type(s) of object(s).
multiple
In Java, polymorphic method binding occurs ____________________.
In Java, polymorphic method binding occurs ____________________.
at run-time
In Java, a(n) ___________________ is a collection of constants and abstract methods.
In Java, a(n) ___________________ is a collection of constants and abstract methods.
interface
Which of the following is true regarding the method call spot.speak() with Animal spot = new Dog();?
Which of the following is true regarding the method call spot.speak() with Animal spot = new Dog();?
What will the following method call a.compareTo(b) return if Object a is larger than Object b?
What will the following method call a.compareTo(b) return if Object a is larger than Object b?
In order to create a class that implements an interface, the __________________ keyword is used.
In order to create a class that implements an interface, the __________________ keyword is used.
What will happen if you try to call a.wagTail() when a is declared as Animal a = new Dog();?
What will happen if you try to call a.wagTail() when a is declared as Animal a = new Dog();?
The commitment to execute certain code to carry out a method invocation is referred to as ______________.
The commitment to execute certain code to carry out a method invocation is referred to as ______________.
It is possible to create an object by instantiating the Animal interface.
It is possible to create an object by instantiating the Animal interface.
A parameter to a method can be polymorphic.
A parameter to a method can be polymorphic.
An interface cannot declare any instance variables.
An interface cannot declare any instance variables.
If a class implements an interface, it cannot extend another class.
If a class implements an interface, it cannot extend another class.
How does inheritance support polymorphism?
How does inheritance support polymorphism?
What is the difference between a class and an interface?
What is the difference between a class and an interface?
Describe the Comparable interface.
Describe the Comparable interface.
Flashcards
Polymorphic Reference
Polymorphic Reference
A reference variable that can point to objects of different classes, as long as they share a common superclass or interface.
Polymorphic Method Binding
Polymorphic Method Binding
The process of determining which method implementation to call at runtime based on the actual type of the object.
Interface
Interface
A blueprint for classes that defines a set of abstract methods and constants. Classes that implement an interface must provide concrete implementations for all abstract methods.
Polymorphism in Action
Polymorphism in Action
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compareTo() Method
compareTo() Method
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implements Keyword
implements Keyword
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Compile-time Error for Subclass Method
Compile-time Error for Subclass Method
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Binding
Binding
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Instantiating an Interface
Instantiating an Interface
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Polymorphic Parameter
Polymorphic Parameter
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Interface Variables
Interface Variables
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Inheritance and Interface Implementation
Inheritance and Interface Implementation
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Inheritance and Polymorphism
Inheritance and Polymorphism
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Class vs. Interface
Class vs. Interface
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Comparable Interface
Comparable Interface
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Study Notes
Polymorphism
- Polymorphic reference can refer to multiple types of objects.
- In Java, polymorphic method binding occurs at run-time, meaning the method invoked is determined by the object’s actual type.
Interfaces
- An interface in Java consists of constants and abstract methods.
- A class implementing an interface uses the "implements" keyword.
Method Overriding
- If a Dog class overrides a method from a parent Animal class, calling
spot.speak()will invoke the Dog's overridden method. - If the Dog class implements the Animal interface with an additional method
wagTail, trying to calla.wagTail()will result in a compile-time error becausewagTail()is not defined in the Animal interface.
Object Comparison
- The
compareTomethod will return a number greater than 0 if the first object is larger than the second, zero if they are equal, or less than 0 if the first is smaller.
Binding and Instantiation
- Binding refers to the commitment to execute certain code for a method invocation.
- It is false that an object can be instantiated from an interface; interfaces cannot be instantiated.
- It is true that methods' parameters can be polymorphic, allowing for various object types.
Class vs. Interface
- A class can be instantiated, while an interface cannot.
- A class that implements an interface can still extend another class.
Comparable Interface
- The Comparable interface includes a method called
compareTothat returns three possible values: greater than 0, equal to 0, or less than 0, indicating the comparative result between objects.
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Description
Test your understanding of Java polymorphism and interfaces with this quiz. It covers key concepts such as polymorphic references, method binding at run-time, and the structure of interfaces in Java. Perfect for any Java programming student!
