Please Answer All the Questions

Question 1

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 public.

An equals method must be added.

The variable chosen must be declared as private.

A toString method must be added.

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

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 (); }

I and III only

I only

III only

I, II and III

II only

Question 3 1 pts Which of the following is a correct declaration for a Spinner object as written? Spinner s = 20; Spinner s = new Spinner(15); Spinner s = Spinner (15); new Spinner s = Spinner(15); Spinner = s; Flag this Question Question 4 1 pts Which of the following is true about classes and objects? It is possible to have many classes of the same object. Objects can be declared abstract. Objects have a reference pointing to their location in memory. A class is an instance of an object. Classes have a reference pointing to their location in memory. Flag this Question Question 5 1 pts 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. The method two 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. Flag this Question Question 6 1 pts Consider the following code: String vocabulary[] = new String [50]; The index of the first value is ______ and the last index is ______. 1 51 0 50 1 49 1 50 0 49 Flag this Question Question 7 1 pts 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 5 7 8 8 4 1 6 3 2 3 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 Flag this Question Question 8 1 pts When using ______ search, the array does not need to be ordered. insertion selection merge binary linear Flag this Question Question 9 1 pts Which of the following is NOT true about ArrayList objects? 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. ArrayList can only hold one data type. Flag this Question Question 10 1 pts Which of the following implements the Comparable interface? String Object Math List ArrayList Flag this Question Question 11 1 pts 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 Nothing is printed Cookies Trail mix Celery Cookies chips Celery Cookies nachos chips Trail mix Celery Flag this Question Question 12 1 pts 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 equal Nothing, there is an error equalnot equal not equal Flag this Question Question 13 1 pts 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; 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 answers listed. 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]; } Flag this Question Question 14 1 pts 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 -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 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 4 6 -15 5 11 21 -11 -10 3 4 -10 -18 -21 14 -23 Flag this Question Question 15 1 pts 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; } } II and III only I only II only I, II and III III only Flag this Question Question 16 1 pts 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 * grid.length grid.length grid[0].length grid.length * grid[0].length grid.length[0] * grid[0].length Flag this Question Question 17 1 pts 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]); 7 10 12 11 6 Flag this Question Question 18 1 pts 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 the elements in the even rows in the array. It finds the sum of every other element 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. Flag this Question Question 19 1 pts 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 2 and 3. Initializes the values in the array. Swaps rows 2 and 3. Swaps rows 1 and 2. Swaps columns 1 and 2. Flag this Question Question 20 1 pts 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 only III only II only II and III only I, II and III