Unit 9 2D Arrays Practice 1

Which of the following is the correct way to declare a 2D array in Java?

• int[][] array = new int[3][3];

• int array = new int[3,3];

• int array[3][3];

• int[][] array = {3,3};

How do you access the element in the second row and third column of a 2D array named `matrix`?

• matrix[2][3]

• matrix[1][2]

• matrix[3][2]

• matrix[2][1]

What is the output of the following code snippet?

int[][] array = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
System.out.println(array[0][2]);

• 1

• 2

• 3

• 6

Which of the following correctly initializes a 2D array with 2 rows and 3 columns?

• int[][] array = new int[2][3];

• int[][] array = new int[3][2];

• int[][] array = new int[2,3];

• int[][] array = new int[3][3];

Consider the following code: ```java int[][] matrix = new int[3][3]; matrix[0][0] = 5; ``` What is the value of `matrix[0][0]` after execution?

• 0

• 5

• null

• undefined

Which of the following statements is true about nested arrays in Java?

• All rows in a 2D array must have the same number of columns.

• Each row in a 2D array can have a different number of columns.

• A 2D array cannot contain other arrays.

• A 2D array must be square (same number of rows and columns).

What is the result of the following code? int[][] array = {{1, 2}, {3, 4, 5}, {6}}; System.out.println(array[1][2]);

• 3

• 4

• 5

• ArrayIndexOutOfBoundsException

Which of the following is a correct way to traverse a 2D array using a nested loop?

• java for (int i = 0; i < array.length; i++) { for (int j = 0; j < array[i].length; j++) { System.out.println(array[i][j]); } }

• java for (int i = 0; i < array.length; j++) { for (int j = 0; j < array[i].length; i++) { System.out.println(array[i][j]); } }

• java for (int i = 0; i < array.length; i++) { for (int j = 0; j < array.length; j++) { System.out.println(array[i][j]); } }

• java for (int i = 0; i < array[i].length; i++) { for (int j = 0; j < array.length; j++) { System.out.println(array[i][j]); } }

What is the output of the following code?

int[][] array = {{1, 2, 3}, {4, 5, 6}};
System.out.println(array.length);

• 2

• 3

• 6

• 5

How do you declare a 2D array with 4 rows and 5 columns in Java?

• int[][] array = new int[4][5];

• int[][] array = new int[5][4];

• int[][] array = new int[4,5];

• int[][] array = new int[5,5];