Unit 8 Review

Which of the following correctly represents the number of items in a 2D array called 'matrix'?

• matrix.length - matrix[0].length - 1

• matrix.length - matrix[0].length

• matrix.length * matrix[0].length

• matrix[0].length - matrix.length

Which of the following represents the correct nested loop headers to traverse through a 2D array called "table" of String values?

• for (String row : table){ for(String str : row){

• for (String[] row : grid){ for(String str : row){

• for(String[][]row:table){

    for (String[] str :row){

• for (String[] row : grid){

    for(String[] str : row){

Which of the following statements puts the word "answer" into a 5x5 array of strings at the 2nd column and 4th row?

• String[3][1] = "answer"

• String[2][4] = "answer"

• String[1][3] = "answer"

• String[4][2] = "answer"

Which of the following represents the correct way to create a two-dimensional array of strings?

1. I. String[][] values = new String[][];

2. II. String[][] values = new [{“A”, “B”}][{“C”, “D”}];

3. III. String[][] values = {{“A”, “B”}, {“C”, “D”}};

• I and III only

• I and II only

• III only

• II only

int[][] nums = { {1, 9, 3, 2}, {-2, 0, 5, -1},{7, 8, 4, -6} } ;

What is the value of x after the statement has executed?

int x = nums[2][1] * nums[1][2]+nums[0][1] / nums[0][3];

• 44

• -18

• -4

• 24

int[][] data = new int[4][7];

Which of the following correctly assigns the third row of the table to the numbers 1 through 7?

• for(int i = 0; i <= 6; i++) {

  data[i][3] = i + 1;

  }

• for(int i = 1; i <= 7; i++) {

  data[2][i-1] = i;

  }

• for(int i = 0; i <= 6; i++) {

  data[i-1][i] = i + 1;

  }

• for(int i = 0; i <= 7; i++){

      data[2][i] = i;

  }

int[][] grid = new int[10][10];

Which of the following code snippets will fill a grid with a multiplication table with multiples of 1 to 10?

• for(int a=0;a<grid[0].length; a++) {

  for(int b=0;b<grid.length;b++){

  grid[a][b] = a * b; }}

• for(int a = 0; a < grid.length; a++) { for(int b = 1; b < grid.length; b++) { grid[a+1][b+1] = a * b; }}

• for(int a=0;a<grid.length;a++){

  for(int b=0;b<grid[0].length; b++){

  grid[a][b]=(a+1)*(b+1); }}

• for(int a=1;a<grid.length; a++){

      for(int b=1;b<grid[0].length; b++){

          grid[a][b] = a * b;}}

for (int r = 0; r < numbers.length; r++) {
        for (int c = 0; c < numbers[0].length - 1; c++) {
            if (numbers[r][c + 1] > numbers[r][c]) {
                numbers[r][c] = numbers[r][c + 1];
}}}

If numbers contains the following code executes, what are the contents of numbers after the code executes?

int[][] numbers = { {3, 4, 5, 6}, {9, 5, 2, 4} };

• {{3, 4, 5, 6},
  {9, 5, 2, 4}}

• {{4, 5, 6, 6},

  {9, 5, 4, 4}}

• {{6, 6, 6, 6},
  {4, 4, 4, 4}}

• {{4, 5, 6, 6},

  {5, 2, 4, 4}}

int[][] table = {{2, 3, 4, 5}, {1, 1, 2, 2,}, {5, 3, 2, 1}};

int sum = 0;

int x = table[1].length - 1;

for (int r = 0; r < 2; r++){

   sum += table[r][x];}

What is the value of sum after the code is executed?

• 5

• 8

• 7

• 6

String[][] arr = new String[2][3];

for (int r = 0; r < arr.length; r++) {

    for (int c = 0; c < arr[0].length; c++) {

      if (r < c)

          arr[r][c] = "*";

       else if (r == c)

          arr[r][c] = "#";

else

          arr[r][c] = "%"; } }

What are the contents of arr after the code segment has executed?

• # * * % # *

• * * # * # %

• * * * # # #

• # * # % # %