Basics

Question 1

Class?

Answer 1

A blueprint that defines the variables and the method common to all objects of a certain kind.

Question 2

Object?

Answer 2

Instances of a specific class.

A self-contained component which consists of methods and properties to make a particular type of data useful

Question 3

Subclassing?

Answer 3

A subclass reuses code from a base class, or the superclass

Question 4

Static methods?

Answer 4

Methods can be called without creating an object of a class

Question 5

Instance methods?

Answer 5

Methods that requires an object of the class before the method can be called.

To invoke, create an object of the class within which the method is contained

Question 6

Variable?

Answer 6

Containers for storing datavalues (int, string…)

Question 7

Attribute?

Answer 7

Metadata of a programs objects, whilst a variable is a program object

Question 8

Abstract class?

Answer 8

Can not be instantiated, but can be subclasses. Define the base-behaviour of subclasses(objects)

Question 9

Interfaces?

Answer 9

Completely abstract class used to group related methods with empty bodies. All methods defined by an interface must appear in a class which implements said interface

Question 10

Static types?

Answer 10

A type defined during compilation, and will be same throughout. Benefit that faults can be detected early and fix them.

Question 11

Dynamic types?

Answer 11

Data decided at run-time(run-time polymorphism)

Question 12

Interface inheritance?

Answer 12

When a class implements an interface, it and its subclasses inherit the methods within the interface

Question 13

Dynamic binding?

Answer 13

Choice between several different possible implementations of a polymorphic method(i.e. an overriden method), decided at run-time

Question 14

Primitive types?

Answer 14

There are 8 primitve types… Stores values

Question 15

Reference types?

Answer 15

Hold a reference to objects and provides a means to access those objects stored somewhere in memory. Includes integers, Arrays, Strings

Question 16

Overloading?

Answer 16

Two methods have the same nam, which one is chosen is at compilation(static)

Question 17

Overriding?

Answer 17

Subclasses overrides a method created in a superclass. Used when the implementation of a certain behaviour must be determined dynamically, stemming from the objects handling behaviour differently. Method is polymorphic.

Question 18

Encapsulation?

Answer 18

Information-hiding mechanism. Must declare class variables/attributes as private and provide public getters and setters.

Question 19

Superclass?

Answer 19

A class that defines the standard behaviour for subclasses which create objects

Question 20

Subclass?

Answer 20

A specific subtype of an object type, that inherits the attributes of the superclass

Question 21

Constructors?

Answer 21

Called at the creation of an object. It is defined in the class of the object, and should always have the same name as the class it is contained within. Not implicitly inherited by subclasses from superclasses. Its job is to initialize the instance varaibles of the object.

Question 22

Initilization?

Answer 22

Is a line of coe placed outside any method. Gives a variable its inital data

Question 23

Aliasing?

Answer 23

Means that more than one reference is tied to the same object