Quiz 7
What does a derived class automatically inherit from the base class?
All of the above
The following statement creates an array of three Animal references.
Animal[] ref = new Animal[3];
The keyword extends indicates polymorphism.
False
When you create a class that uses an interface, you include the keyword extends.
False
When you define a derived class, you give only the added instance variables and the added methods as well as all the methods from the base class
False
When you define a derived class, you give only the added instance variables and the added methods as well as all the methods from the base class.
False
The class __________ is an ancestor class of all Java classes.
Object
If the final modifier is added to the definition of a method, this means:
The method may not be redefined in the derived class.
A derived class is a class defined by adding instance variables and methods to an existing class.
True
Overriding is when a derived class redefines a method from the base class.
True
Private methods of the base class are not available for use by derived classes.
True
A super class is also called a
base class
When you create a new subclass in Java, neither the superclass source code nor the superclass _____ is changed.
bytecode
Inheritance is the process by which a new class - known as a _________ - is created from another class, called the _____________.
derived class, base class
If Java did not allow you to ____ classes, you would need to create every part of a program from scratch.
extend
In using the keyword this in place of super(), the invocation of this must be the ___________ action taken by the constructor.
first
When a class both extends and implements, by convention the ____ clause is last in the class header.
implements
When you assign a variable or constant of one type to a variable of another type, the behavior is called ____.
implicit conversion
The keyword extends indicates:
inheritance
Instead of using the automatic toString() method with your classes, it is usually more useful to write your own ____ version of the toString() method that displays some or all of the data field values for the object with which you use it.
overloaded
A(n) ____ is not an object, but it points to a memory address.
reference
Inheritance promotes code _____.
reuse
A derived class is also called a
sub class
The special syntax for invoking a constructor of the base class is:
super()
The Object class ____ method converts an Object into a String that contains information about the Object.
toString()
You may substitute the keyword this for super() to call a constructor of the derived class.
True
A(n) ____ class is one from which you cannot create any concrete objects, but from which you can inherit.
abstract
An object of a derived class has the type of the derived class, and it also has the type of the base class, and more generally, has the type of every one of its ________ classes.
ancestor