Unit 8 - 2D Array

Question 1

2D array

Answer 1

An array of arrays
Can be better way to store data
Exp - seating chart of students

Question 2

Rectangular 2D array

Answer 2

Each row array has same number of elements

Question 3

Declaring a 2D array

Answer 3

DataType [ ] [ ] nameOf2DArray

Question 4

Initializing a 2D array

Answer 4

Needs to know # of rows and columns

new DataType [r] [c]

Question 5

If you know what elements of 2D arrrays you want to include, you can

Answer 5

initialize the 2D array with a set of initializer lists

Question 6

Initializer lists

Answer 6

Starts & ends with curly brackets {}
Each row has its own initializer list
Separating elements and initializer lists with commas

{{“Alice”,”Rob”,”Cody”},{“Robin”,”Becky”,”Kisha”}}

Question 7

We refer to 2D array’s size by

Answer 7

# of rows along with # of columns
r by c

Question 8

How to determine number of rows in a 2D array

Answer 8

r = grades.length

Question 9

How to determine number of column in a 2D array

Answer 9

c = grades[0].length

Question 10

How to access an element in a 2D array

Answer 10

name of array variable
2 sets of square brackets
index of row where element is located
index of row where element is located

grade [5,2]

Question 11

How to access an element in a 2D array

Answer 11

grade [5,2] = grade [5,2] + 1

Question 12

How to create a new 2D array

Answer 12

DataType [ ] [ ] nameOf2DArray = new DataType [r][c];

String [ ] [ ] seating = new String [10][3}

Question 13

In order to print out the contents of a 2D array,

Answer 13

you need to use for loops inside of for loops

Question 14

In order to print out the contents of a 2D array, and you don’t know the specific dimensions,

Answer 14

you need to use
nameOf2DArray.length for row and
nameOf2DArray [0].length for column

Question 15

Nested iteration statements can be written to traverse 2D array in

Answer 15

row-major order or column-major order