Revature Interview Questions with correct answers
Object Correct Answer-An instance of a class
Class Correct Answer-Blueprint/prototype from which objects are
created
Inheritance Correct Answer-subclasses can inherit states/behaviors of
superclasses
interface Correct Answer-contract between class and outside world;
when a class implements an interface, it promises to provide the
behavior published by that interface
package Correct Answer-a namespace for organizing classes &
interfaces in a logical manner; makes large software projects easier to
manage
Encapsulation Correct Answer-Hiding the internal state of an object and
requiring all interaction to be performed through an object's methods
(accessors and mutators).
Example: In a Bicycle class, method changeGear() could be
implemented so as to only accept values between 1 and 6
Benefits of Objects Correct Answer-Modularity
Information-Hiding
,Code re-use
Pluggability and debugging ease
Modularity Correct Answer-source code for an object can be
written/maintained independently of source code for other objects.
objects can be easily passed around the system once they've been
created.
Information-Hiding Correct Answer-By interacting only with object's
methods, details of internal implementation stay secret from outside
world.
Code re-use Correct Answer-Complex objects only need to be coded
once; you can use classes that have already been created by others.
Pluggability/Debugging Ease Correct Answer-If an object is causing
problems, you can easily remove it and put something else in its place.
Example: replace a bolt that is broken, not the whole machine.
How to use the changeGear() method on a Bicycle bike1? Correct
Answer-bike1.changeGear();
How many superclasses can a subclass have? Correct Answer-ONLY
ONE
,How many subclasses can inherit from the same superclass? Correct
Answer-Infinitely many
What is the main benefit of using inheritance? Correct Answer-The
subclass contains all of the methods/fields of the superclass, but the
subclass' code focuses on the unique aspects, making code simpler and
easier to read.
Why must the superclass' code be carefully documented? Correct
Answer-Because that code is not physically in the subclass.
Interface Correct Answer-the methods that a class is required to contain;
empty methods that are related
Should the methods in an interface be public or private? Correct
Answer-MUST be public
Packages Correct Answer-organizes a set of related classes/interfaces;
like a folder on your computer
class library Correct Answer-a set of packages
API Correct Answer-Application Programming Language: Java's library
of classes that you can use in your own applications.
, What do the Java API's packages represent? Give examples. Correct
Answer-tasks for general purpose programming: String, File, Socket,
some for developing GUIs.
What is a benefit of using packages? Correct Answer-It allows
developers to focus on the design of an application and NOT the
technical stuff that makes it work.
Real-world objects contain BLANK and BLANK. Correct Answer-
State, behavior
A software object's state is stored in BLANK Correct Answer-fields
A software object's behavior is exposed through BLANK Correct
Answer-methods (functions)
Hiding internal data from the outside world, and accessing it only
through publicly exposed methods is known as data BLANK Correct
Answer-Encapsulation
A blueprint for a software object is called a BLANK Correct Answer-
class
Common behavior can be defined in a BLANK and inherited into a
BLANK using the BLANK keyword Correct Answer-superclass,
subclass, extends
Object Correct Answer-An instance of a class
Class Correct Answer-Blueprint/prototype from which objects are
created
Inheritance Correct Answer-subclasses can inherit states/behaviors of
superclasses
interface Correct Answer-contract between class and outside world;
when a class implements an interface, it promises to provide the
behavior published by that interface
package Correct Answer-a namespace for organizing classes &
interfaces in a logical manner; makes large software projects easier to
manage
Encapsulation Correct Answer-Hiding the internal state of an object and
requiring all interaction to be performed through an object's methods
(accessors and mutators).
Example: In a Bicycle class, method changeGear() could be
implemented so as to only accept values between 1 and 6
Benefits of Objects Correct Answer-Modularity
Information-Hiding
,Code re-use
Pluggability and debugging ease
Modularity Correct Answer-source code for an object can be
written/maintained independently of source code for other objects.
objects can be easily passed around the system once they've been
created.
Information-Hiding Correct Answer-By interacting only with object's
methods, details of internal implementation stay secret from outside
world.
Code re-use Correct Answer-Complex objects only need to be coded
once; you can use classes that have already been created by others.
Pluggability/Debugging Ease Correct Answer-If an object is causing
problems, you can easily remove it and put something else in its place.
Example: replace a bolt that is broken, not the whole machine.
How to use the changeGear() method on a Bicycle bike1? Correct
Answer-bike1.changeGear();
How many superclasses can a subclass have? Correct Answer-ONLY
ONE
,How many subclasses can inherit from the same superclass? Correct
Answer-Infinitely many
What is the main benefit of using inheritance? Correct Answer-The
subclass contains all of the methods/fields of the superclass, but the
subclass' code focuses on the unique aspects, making code simpler and
easier to read.
Why must the superclass' code be carefully documented? Correct
Answer-Because that code is not physically in the subclass.
Interface Correct Answer-the methods that a class is required to contain;
empty methods that are related
Should the methods in an interface be public or private? Correct
Answer-MUST be public
Packages Correct Answer-organizes a set of related classes/interfaces;
like a folder on your computer
class library Correct Answer-a set of packages
API Correct Answer-Application Programming Language: Java's library
of classes that you can use in your own applications.
, What do the Java API's packages represent? Give examples. Correct
Answer-tasks for general purpose programming: String, File, Socket,
some for developing GUIs.
What is a benefit of using packages? Correct Answer-It allows
developers to focus on the design of an application and NOT the
technical stuff that makes it work.
Real-world objects contain BLANK and BLANK. Correct Answer-
State, behavior
A software object's state is stored in BLANK Correct Answer-fields
A software object's behavior is exposed through BLANK Correct
Answer-methods (functions)
Hiding internal data from the outside world, and accessing it only
through publicly exposed methods is known as data BLANK Correct
Answer-Encapsulation
A blueprint for a software object is called a BLANK Correct Answer-
class
Common behavior can be defined in a BLANK and inherited into a
BLANK using the BLANK keyword Correct Answer-superclass,
subclass, extends
