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