object oriented programming

Question 1

class abstraction

Answer 1

the separation of class implementation from the use of the class

Question 2

implementation

Answer 2

declaration of methods and attributes and code

Question 3

class encapsulation

Answer 3

hide the details of class implementation from the user

hide the details, focus on whats important

Question 4

class contract

Answer 4

pretty much what the API is. what methods and attributes are availible and what are their descriptions. user should only look at this, no further details

Question 5

class inheritance usage

Answer 5

public class extends

Question 6

public

Answer 6

class can be seen everywhere in java

Question 7

protected

Answer 7

only package members and subclasses can see it

Question 8

no modifier

Answer 8

only package members can see it, no subclasses

Question 9

private

Answer 9

member can only be seen in its own class

Question 10

polymorphism

Answer 10

variable of a superclass can refer to a subclass/more specialized class

area of 2dfigure can be circle or square

opposite of super()?

Question 11

overloading

Answer 11

same method name can have different parameter list

Question 12

overriding

Answer 12

subclass methods can override superclasses definitions. use @override modifier. so when you want to use polymorphism, this may be useful

Question 13

concrete class

Answer 13

class can be used to create objects

Question 14

abstract class

Answer 14

class CANNOT be used to create objects. they are allowed to have constructors that subclasses can use. concreate subclasses must implement all abstract methods or be abstract itself.

Question 15

static

Answer 15

do not need an instance to be called. alot of core java functions/libraries are this

Question 16

interface

Answer 16

class like construct that only has constants and abstract methods

• cannot have constructors
• all variables must be public, static, or final
• all methods must be public abstract
• interface can be used with extends keyword, and interface can extend multiple other interfaces
• class can extend multiple interfaces
• can be used as data type

Question 17

when to use interface

Answer 17

interfaces model pure behavior. ANSWER WHAT CLASS CAN DO.

abstracts can save duplicate code

remember that you implement multiple interfaces but only extend from one superclass