Object-Oriented Programming Concepts

Question 1

Real-world objects share two characteristics: state and …

Answer 1

behaviour

Question 2

… objects are conceptually similar to real-world objects

Answer 2

Software

Question 3

Where does An object store its state?

Answer 3

in fields

Question 4

How does An object exposes its behavior?

Answer 4

through methods

Question 5

What does An object operate?

Answer 5

object’s internal state

Question 6

What for does object serve as the primary mechanism?

Answer 6

for object-to-object communication

Question 7

Hiding internal state and requiring all interaction to be performed through an object’s methods is known as …

Answer 7

data encapsulation

Question 8

The source code for an object can be written and maintained independently of the source code for other objects

Answer 8

Modularity

Question 9

By interacting only with an object’s methods, the details of its internal implementation remain hidden from the outside world

Answer 9

Information-hiding

Question 10

If a particular object turns out to be problematic, you can simply remove it from your application and plug in a different object as its replacement.

Answer 10

Pluggability

Question 11

… is a blueprint or prototype from which objects are created

Answer 11

Class

Question 12

each class is allowed to have … direct superclass

Answer 12

one

Question 13

each superclass has the potential for an … of subclasses

Answer 13

unlimited number

Question 14

At the end of your subclass declaration, use the … keyword

Answer 14

extends

Question 15

… makes code for your subclasses easy to read

Answer 15

Inheritance

Question 16

You must take care to … the state and behavior that each superclass defines

Answer 16

properly document

Question 17

Superclass code … in the source file of each subclass

Answer 17

will not appear

Question 18

What do methods form ?

Answer 18

the object’s interface with the outside world

Question 19

… is a group of related methods with empty bodies.

Answer 19

interface

Question 20

What is an interface?

Answer 20

A group of related methods with empty bodies.

Question 21

To implement this interface you have to …

Answer 21

change new class name and use implements keyword

Question 22

Which keyword do you use to implement interface?

Answer 22

implements

Question 23

What do interfaces form?

Answer 23

a contract between the class and the outside world

Question 24

When must all methods defined by that interface appear in class source code?

Answer 24

before the class will successfully compile

Question 25

What Is a Package?

Answer 25

namespace that organizes a set of related classes and interfaces

Question 26

… namespace that organizes a set of related classes and interfaces

Answer 26

package

Question 27

Java platform provides an enormous class library (…)

Answer 27

a set of packages

Question 28

What does Java API allow programmer?

Answer 28

focus on the design of your particular application