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26 Cards in this Set
- Front
- Back
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A common form of reuse of classes is _____. |
inheritance |
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We can organize classes into _____ of functionality. |
hierarchies |
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The class at the top of the hierarchy |
superclass |
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_____ defines instance variables and methods common to all classes in the hierarchy. |
superclass |
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A _____ can inherit directly from only one _____. |
subclass superclass |
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(T/F) A class can only be either a subclass or a superclass. |
False (A class can be both a subclass and a super class.) |
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A subclass which adds fields and methods |
Override (means hide) |
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All classes inherit from the _____ class. |
Object |
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The superclass name specified after the extends keyword is called the _____. |
direct superclass |
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_____ members are inherited by subclasses (like public members), while still being hidden from client classes(like private members). |
protected |
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Constructors (are, are not) inherited. |
are not |
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"The default constructor of the subclass automatically calls the default constructor of the superclass." describes _____. |
Implicit invocation |
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A subclass can _____ an inherited method by providing a new version of the method. |
override (or replace) |
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When the client calls the method, it will call the _____ version. The _____ method is invisible to the client of the subclass. |
subclass superclass |
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Declaring fields as _____ allows them to be accessed directly by subclass methods. |
protected |
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_____ is a class that is not completely implemented. |
An abstract class |
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Usually, the abstract class contains at least one _____. |
abstract method |
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An abstract method specifies an API but doesn't provide _____. |
an implemention |
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An abstract class (can, cannot) be used to instantiate objects. |
Cannot
(Because the class is not complete.) (But an object reference to it can be declared.) |
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Abstract methods (can, cannot) be called. |
cannot
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Abstract methods (can, cannot) be declared as private or static. |
cannot
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An important concept in inheritance is that an object of a subclass is also an object of any of its superclasses. That concept is the basis for an important OOP feature, called _____. |
polymorphism |
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_____ simplifies the processing of various objects in the same class hierarchy. |
polymorphism (Because we can use the same method call for any object in the hierarchy using a superclass object reference.) |
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Four requirements of polymorphism |
1) the classes are in the same hierarchy. 2) all subclasses override the target method. 3) a subclass object reference is assigned to a superclass object reference. 4) The superclass object reference is used to call the target method. |
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To allow a class to inherit behavior from multiple sources, Java provides the _____. |
interface |
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All interface cannot be instantiated because they are _____. |
abstract |
