Unit 5 - Two-Dimensional Arrays

Consider the code to the left.

What is printed out as a result of executing this code?

• H

• L

• M

• N

• ArrayIndexOutOfBounds

Consider the following code segment, where letters is a two-dimensional (2D) array that contains possible letters. The code segment is intended to print "PIG".

String[][] letters = { {"A", "B", "C", "D"},

{"E", "F", "G", "H"},

{"I", "J", "K", "L"},

{"M", "N", "O", "P"}};

System.out.println( /* missing code */ );

Which of the following could replace /* missing code */ so that the code segment works as intended?

• letters[4][4] + letters[3][1] + letters[2][3]

• letters[3][3] + letters[2][0] + letters[1][2]

• letters[4][3] + letters[3][0] + letters[2][2]

• letters[3][3] + letters[0][2] + letters[2][1]

• letters[4][4] + letters[1][3] + letters[3][2]

Consider the following two-dimensional array words.

String[][] words = { {"about", "actor", "admit", "agile"},

{"badge", "basic", "berry", "bingo"},

{"cacti", "cedar", "chair", "close"}};

What is the fifth element visited when row-major traversal is performed on words?

• about

• agile

• badge

• basic

• cedar

Consider the Code segment to the left:

What is printed when num has the value 5?

• 4 1 3

• 5 6 8

• 6 7 9

• 8 5 7

• 9 6 8

Consider the Code segment to the left:

What is printed when num has the value 5?

• 4 1 3

• 5 6 8

• 6 7 9

• 8 5 7

• 9 6 8

Consider the following two-dimensional array words.

String[][] words = { {"about", "actor", "admit", "agile"},

{"badge", "basic", "berry", "bingo"},

{"cacti", "cedar", "chair", "close"}};

What is the fifth element visited when column-major traversal is performed on words?

• about

• agile

• badge

• basic

• cedar

Consider the code to the left:

Which of the following is the reason why an exception is thrown when the code is executed?

• The row index is out of range because the for loop on line 5 iterates one time too many.

• The column index is out of range because the for loop on line 6 iterates one time too many.

• The column index is out of range because the indexes are in the wrong order.

• The row index is out of range because the indexes are in the wrong order.

Consider the method, reverse, to the left:

Which is intended to return the reverse the elements of arr. For example, if arr contains {{1, 2, 3}, {4, 5, 6}}, then reverse(arr) should return {{6, 5, 4}, {3, 2, 1}}.

What choice could replace /* missing statement */ so that reverse works as intended?

• ret[row][col];

• ret[arr.length - row - 1][arr[0].length - col - 1]

• arr[arr.length - row - 1][arr[0].length - col - 1]

• ret[arr.length - row][arr[0].length - col]

• arr[arr.length - row][arr[0].length - col]

Consider to the left the method, reverse, which is intended to return the reverse the elements of arr. For example, if arr contains {{1, 2, 3}, {4, 5, 6}}, then reverse(arr) should return {{6, 5, 4}, {3, 2, 1}}.

The code does not work as intended. Which of the following arrays can be passed to reverse to

show that the method does NOT work as intended?

• {{0}}

• {{0}, {0}}

• {{0, 1}, {0, 1}}

• {{0, 0}, {1, 1}, {0, 0}}

• {{0, 0}, {1, 1}, {1, 1}, {0, 0}}

Consider the following code segment.

int[][] arr = {{0, 0, 0}, {1, 1, 1}, {2, 2, 2},  {3, 3, 3}};

for (int[] row : arr) {

     for (int item : row) {

         System.out.print(item + " ");

     }

     System.out.println(" ");

}

How many times will the statement System.out.print(item + " ") be executed?

• 0

• 3

• 4

• 9

• 12