Chapter 3 - Primitives and References

Question 1

Variables come in what two flavors?

Answer 1

Primitive and Object Reference

Question 2

What are local variables

Answer 2

Variables declared within a method

Question 3

What are arguments

Answer 3

Values sent to a method by the calling code

Question 4

What are return types

Answer 4

Values sent back to the caller of the method

Question 5

Primitives hold?

Answer 5

Fundamental Values (ints, booleans, floats)

Question 6

Use the dot operator on a reference variable to say?

Answer 6

Use the thing before the dot to get me the thing after the dot

Question 7

Think of the dot operator as

Answer 7

pressing a button on a remote

Question 8

An object reference variable is

Answer 8

full of bits representing a way to get to the object

Question 9

Three steps of object declaration, creation and assignment

Answer 9

Declare a reference variable ... Dog myDog
Create an object ... new Dog();
Link the object and the reference ... Dog myDog = new Dog();

Question 10

Think of a dog reference variable as

Answer 10

a Dog remote control. Use it to get the object to do something (invoke methods)

Question 11

What’s a null reference

Answer 11

A reference variable that doesn’t refer to anything

Question 12

Arrays are always

Answer 12

Objects

Question 13

Declare a dog array variable

Answer 13

Dog [] pets;

Question 14

What’s a primitive variable value

Answer 14

The bits representing the value

Question 15

What’s a reference variable value

Answer 15

The bits representing a way to get to an object on the heap

Question 16

A reference variable is like?

Answer 16

A remote control

Question 17

When does a reference variable have a null value

Answer 17

When it’s not referencing any object

Question 18

Arguments

Answer 18

Values sent to a method by the calling code

Question 19

Return types

Answer 19

Values sent back to the caller of the method

Question 20

Think of a variable as?

Answer 20

A coffee cup. It holds something. It has a size and type

Question 21

A variable needs a name so

Answer 21

you can use that name in code

Question 22

myDog.bark() means

Answer 22

use the object referenced by the variable myDog to invoke the bark() method.

Question 23

An object reference is just

Answer 23

another variable value

Question 24

Primitive variable

Answer 24

byte x = 7;

The bits representing 7 go into the variable

Question 25

Reference variable

Answer 25

Dog myDog = new Dog();
The bits representing a way to get to the Dog object go into the variable

Question 26

An array is like?

Answer 26

A tray of cups

Question 27

Every element in an array is just a?

Answer 27

A variable. Primitive or Reference

Question 28

In a dog array each element can hold

Answer 28

a remote control to a Dog.

Question 29

When the dog is in an array we don’t have?

Answer 29

an actual variable name. Use array notation and push the remote on an object a particular index in the array.

Dog[] myDogs = new Dog[3];
myDogs[0] = new Dog();
myDogs[0].name = "Fido"
myDogs[0].bark();