Comp 1409 Pre-Midterm

Question 1

What is a Java Class and an example?

Answer 1

A file that describes a general category in terms of data and behaviours ie a book class describes title, author, date written, that the book can be opened and closed etc

Question 2

What is an object?

Answer 2

One specific instance of a class eg in a book class the object would be the title. Every book will have a title.

Question 3

What are instance variables?

Answer 3

an individual piece of data within a class

Question 4

nouns or adjectives should be used to describe what kind of data?

Answer 4

Instance variables

Question 5

What are the 4 primitive data types?

Answer 5

int, double , boolean and char

Question 6

What are the reference (or object) data types?

Answer 6

String and classes

Question 7

What are 2 visibility modifiers (access modifiers) from lesson 2?

Answer 7

public or private, accessible from any class or only from within a class

Question 8

instance variables should always be be private?

Answer 8

True

Question 9

What is a constructor and and what does it do?

Answer 9

A constructor is a special method used to initialize objects when an object of a class is created (is called automatically). Is used to set sensible initial values for object attributes.

Question 10

Constructors should be marked public

Answer 10

F

Question 11

Constructors should have Javadoc comments

Answer 11

T with @param tags explainging each parameter’s conditions

Question 12

What’s the difference between formal arguments and actual arguments

Answer 12

Formal arguments are instance variables in a constructor where as an actual argument is the data in the argument. IE formal argument is variable “title” where as the the actual argument would be “Star Wars”

Question 13

What is a method?

Answer 13

An instruction, a function, a verb

Question 14

How should methods be named?

Answer 14

As verbs

Question 15

What must methods always have to compile?

Answer 15

a return type even if its void

Question 16

Do accessors need the variable return type or should it be void?

Answer 16

It should be the same return type as the instance variable that is getting returned

Question 17

Do you think there are usually more getters than setters?

Answer 17

I hope so because thats what big boss says

Question 18

Are mutators returning the same variable type as the instance variables they are changing?

Answer 18

No they return void

Question 19

What are local variables?

Answer 19

defined within a method. Are created when the method called and destroyed when it ends.

• locals scope only
• private visibility modifier/no visibility modifier

Question 20

Where are instance variables?

Answer 20

Defined within a class. Are created when an object is created and destroyed when the object is destroyed

Question 21

What are static variables?

Answer 21

Belong to the class not each object

• Each object uses the single instance of the instance of the variable
• Declared with keyword static - public static int population
• no object required

Question 22

What are static methods

Answer 22

belong to a class
can only use class (static) variables not instance variables
Can be called without object instantiation
declared with a static keyword

Question 23

What is the final variables?

Answer 23

Instance variables that accept data once and never change

Keyword final

Question 24

Constants - what is they?

Answer 24

Data that are only set once 
Declared with static final keywords at class level
used to represent things that dont change (sucha s the value of Pi)
Often called symbolic constants, named with all caps

Question 25

Are a static method and static variable acceptable?

Answer 25

Yeeess

Question 26

Are instance method and instance variable acceptable?

Answer 26

yes

Question 27

Are instance methods and static variables acceptable?

Answer 27

Oh sure, bud

Question 28

Are Static Methods and Instance variables acceptable?

Answer 28

Not okay. Not okay at all.

Question 29

``` If variable is: Accessible only to the method it is declared in no access modifier no default values It must be what kind of variable? ```

Answer 29

Local

Question 30

``` Variable is Accessible all throughout the class private declared within the class li ```

Answer 30

instance

Question 31

Which operations then assign shoulod you not do? (operation than issign be x += number

Answer 31

dont do *=, /=, %=

Question 32

What are the three ways an overloaded constructor can work/be differentiated?

Answer 32

1. ifferent number of parameters 2. different type of parameters 3. different order of parameters

Question 33

Whats the formatt for switch/case statements?

Answer 33

ublic void printGradeRange(char letterGrade){switch(letterGrade){case(‘A’):case(‘a’):System.out.println(“80 to 100”);break;case(‘B’):case(‘b’):System.out.println(“60 to 79”) default: get rekt