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?

A toString method must be added.

The variable chosen must be declared as public.

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

The variable chosen must be declared as private.

An equals method must be added.

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 (); }

I only

II only

III only

I and III only

I, II, and III

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

Spinner = s;

Spinner s = 20;

Spinner s = Spinner (15);

new Spinner s = Spinner(15);

Spinner s = new Spinner(15);

Which of the following is true about classes and objects?

Classes have a reference pointing to their location in memory.

Objects can be declared abstract.

Objects have a reference pointing to their location in memory.

A class is an instance of an object.

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

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?

The variable x in Thing should be declared abstract.

Item must contain a method named two.

Item must contain a method named one.

Item must contain a variable named x.

The method two in Thing should be declared abstract.

Consider the following code:

String vocabulary[] = new String [50];

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

0 49

0 50

1 49

1 50

1 51

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?

2 4 5 2 2 8 6 8 1 2

4 6 7 7 3 0 5 2 1 2

6 6 6 3 7 7 9 5 8 8

7 7 7 4 8 8 10 6 9 9

5 7 8 8 4 1 6 3 2 3

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

binary

insertion

linear

merge

selection

Which of the following is NOT true about ArrayList objects?

Methods for insertion and deletion are built into the class.

They can be resized.

ArrayList can only hold one data type.

ArrayList can hold many data types at once.

ArrayList is a class data type.

Which of the following implements the Comparable interface?

ArrayList

List

Math

Object

String

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 Trail mix Celery

Cookies nachos chips Trail mix Celery

Cookies chips Celery

Nothing is printed

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");

equal

not equal

equalnot equal

not equalequal

Nothing, there is an error

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 */?

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]; }

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; 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; int temp = a [0][k]; a[0][k] = a[last][k]; a[last][k] = temp; }

None of the above

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);?

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

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

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

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

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

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

II

III

II and III only

I, II, and III

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[0].length

grid.length

grid.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

10

11

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 even elements in the array.

It finds the sum of all elements in the array.

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

Swaps rows 2 and 3.

Initializes the values in the array.

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; }

I

II

III

II and III only

I, II, and III