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.

Question 2

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

Question 3

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;

Question 4

Which of the following is true about classes and objects?

A class is an instance of an object.

Objects can be declared abstract.

Objects have a reference pointing to their location in memory.

It is possible to have many classes of the same object.

Classes have a reference pointing to their location in memory.

Question 5

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.

Question 6

Consider the following code:

String vocabulary[] = new String [50];

The index of the first value is ______ and the last index is ______.

0 50

1 50

0 49

1 49

1 51

Question 7

Consider the following code:

int[] a = {64 , 66 , 67 , 37 , 73 , 70 , 95 , 52 , 81 , 82};

for(int i =0; i < a.length; i++) {

a[i] = a[i] /10;

}

for(int i =0; i < a.length; i++) {

System.out.print(a[i] + " ");

}

What is output?

4 6 7 7 3 0 5 2 1 2

2 4 5 2 2 8 6 8 1 2

5 7 8 8 4 1 6 3 2 3

7 7 7 4 8 8 10 6 9 9

6 6 6 3 7 7 9 5 8 8

Question 8

When using ______ search, the array does not need to be ordered.

insertion

binary

merge

linear

selection

Question 9

Which of the following is NOT true about ArrayList objects?

ArrayList can only hold one data type.

They can be resized.

ArrayList is a class data type.

Methods for insertion and deletion are built into the class.

ArrayList can hold many data types at once.

Question 10

Which of the following implements the Comparable interface?

List

Math

Object

String

ArrayList

Question 11

Consider the following code segment:

ArrayList list = new ArrayList ();

list.add ("Cookies");

list.add ("nachos");

list.add ("chips");

list.add ("Trail mix");

list.add ("Celery");

for (String s: list) {

if (s.toUpperCase().charAt(0) == s.charAt(0)) {

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

}

}

What is printed as a result of executing the code segment?

nachos chips

Cookies chips Celery

Cookies nachos chips Trail mix Celery

Cookies Trail mix Celery

Nothing is printed

Question 12

What is output by the following code segment? Assume a Time class exists.

Time appointment1 = new Time(5, 45);

Time appointment2 = new Time(5, 45);

if (appointment1 == appointment2) {

System.out.print("equal");

} else {

System.out.print("not equal");

}

not equalequal

equalnot equal

not equal

Nothing, there is an error

equal

Question 13

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];

}

Question 14

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

Question 15

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

Question 16

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

Question 17

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

Question 18

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.

Question 19

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.

Question 20

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