Problems 1 3 refer to the following class meant to represent the spinner in a board game:

class Spinner { private int numOptions; private int chosen; public Spinner (int n) { if (n >= 2 && n <= 20) { numOptions = n; } spin (); } public void spin () { chosen = (int)(Math.random () * numOptions) + 1; } } 

Consider the following code:

Spinner s = new Spinner(17); System.out.println(s);

The intention is for this code to print the value stored in chosen. For this to work correctly which of the following must be true?

The variable chosen must be declared as private.

A toString method must be added.

An equals method must be added.

A mutator for the variable method for chosen must be added.

The variable chosen must be declared as public.

Which of the following would be correct declarations for a default constructor?

I.

public Spinner() { this(2); } 

II.

public Spinner() { numOptions = n; } 

III.

public Spinner() { numOptions = 2; spin (); } 

III only

I only

II only

I, II and III

I and III only

Which of the following is a correct declaration for a Spinner object as written?

Spinner s = Spinner (15);

Spinner s = new Spinner(15);

new Spinner s = Spinner(15);

Spinner s = 20;

Spinner = s;

Consider the following class declarations:

public abstract class Thing { private int x; public abstract void one(); public void two () { /* Code not shown */ } /* Code not shown */ } public class Item extends Thing { /* Code not shown */ } 

To instantiate an object of type Item which of the following must be true?

Item must contain a method named two.

The method two in Thing should be declared abstract.

Item must contain a variable named x.

The variable x in Thing should be declared abstract.

Item must contain a method named one.

Which of the following implements the Comparable interface?

List

Math

Object

String

ArrayList

Consider the following method intended to swap the first and last rows in a two-dimensional array:

public static void swapRow (int[][] a) { /* missing code */ } 

Which of the following correctly replaces /* missing code */?

None of the answers listed.

for (int k = 0; k < a[0].length; k++) { int last = a.length; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; }

for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; }

for (int k = 0; k < a[0].length; k++) { int last = a.length; a[0][k] = a[last][k]; a[last][k] = a [0][k]; }

for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; a[0][k] = a[last][k]; a[last][k] = a [0][k]; } 

Consider the following method intended to swap the first and last rows in a two-dimensional array:

public static void swapRow (int[][] a) { /* missing code */ } 

Which of the following correctly replaces /* missing code */?

None of the answers listed.

for (int k = 0; k < a[0].length; k++) { int last = a.length; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; }

for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; }

for (int k = 0; k < a[0].length; k++) { int last = a.length; a[0][k] = a[last][k]; a[last][k] = a [0][k]; }

for (int k = 0; k < a[0].length; k++) { int last = a.length - 1; a[0][k] = a[last][k]; a[last][k] = a [0][k]; }

Consider the following method declaration.

public static void increment(int[][] a) { for (int r = 0; r < a.length; r++) { for (int c = 0; c < a[0].length; c++) { if (a[r][c] >= 0) { a[r][c]++; } else { a[r][c]--; } } } } 

Assume the 2D array, matrix, has been initialized to the following values:

4 6 -15 5 11 21 -11 -10 3 4 -10 -18 -21 14 -23 

What is the value of matrix after the method call, increment(matrix);?

5 7 -14 6 12 22 -10 -9 4 5 -9 -17 -20 15 -22

5 7 -15 6 12 22 -11 -10 4 5 -10 -18 -21 15 -23

5 7 -16 6 12 22 -12 -11 4 5 -11 -19 -22 15 -24

4 6 -16 5 11 21 -12 -11 3 4 -11 -19 -22 14 -24

4 6 -15 5 11 21 -11 -10 3 4 -10 -18 -21 14 -23

Consider the following code.

int[][] matrix = new int[4][5];

Suppose we want to initialize matrix to the following rows and columns.

0 1 2 3 4 4 3 2 1 0 0 1 2 3 4 4 3 2 1 0 

Which of the options below correctly initializes matrix?

I.

for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][j] = j; } } 

II.

for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][matrix[i].length - j - 1] = j; } } 

III.

for (int i = 0; i < matrix.length; i += 2) { for (int j = 0; j < matrix[i].length; j++) { matrix[i][j] = j; matrix[i + 1][matrix[i].length - j - 1] = i; } } 

I only

II and III only

I, II and III

II only

III only

Consider the following code:

int[][] grid = /* code not shown */;

Which of the following could be used to calculate how many cells are in the array?

grid.length[0] * grid[0].length

grid.length * grid[0].length

grid.length * grid.length

grid[0].length

grid.length

Consider the following declaration for a two-dimensional array.

int[][] grid = new int[3][5]; int c = 0; for (int i = 0; i < grid.length; i++) { for (int j = 0; j < grid[i].length; j++) { grid[i][j] = c; c++; } } 

What element is displayed when the following line of code is executed?

System.out.println(grid[2][1]);

6

7

11

10

12

What does the following segment of code do?

int[][] a = /* initialization not shown */; int sum = 0; for(int i = 0; i < a.length; i++) { for(int j = 0; j < a[0].length; j++) { if(i % 2 == 0) { sum += a[i][j]; } } } 

It finds the sum of every other element in the array.

It finds the sum of the elements in the even rows in the array.

It finds the sum of the elements in the even columns in the array.

It finds the sum of all elements in the array.

It finds the sum of the even elements in the array.

Which option best describes what the following algorithm does?

int a [][] = /* initialization not shown */; int j = 2; for (int i = 0; i < a[0].length; i++) { int temp = a[j + 1][i]; a[j + 1][i] = a[j][i]; a[j][i] = temp; } 

Swaps columns 1 and 2.

Swaps columns 2 and 3.

Swaps rows 1 and 2.

Initializes the values in the array.

Swaps rows 2 and 3.

You need a method to find the maximum value in every row of an array. Which of the following methods works as intended?

I.

public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j = 0; j < a[0].length; j++) { if (a[i][j] > max) { max = a[0][j]; } } temp [i] = max; } return temp; } 

II.

public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j =0; j < a[0].length; j++) { if (a[i][j] > max) { max = a[i][j]; } } temp [i] = max; } return temp; } 

III.

public static int[] findMaxList (int a[][]) { int temp [] = new int [a.length]; for(int i = 0; i < a.length; i++) { int max = a[i][0]; for(int j = 0; j < a[0].length; j++) { if(a[i][j] > a[0][j]) { max = a[i][j]; } } temp [i] = max; } return temp; } 

II only

I, II and III

III only

I only

II and III only