Computer Science A Exam 2020

Section I: Multiple-Choice 1. Consider the following code segment. What is printed when the code segment is executed? (A) 0.666666666666667 (B) 9.0 (C) 10.0 (D) 11.5 (E) 14.0 Consider the processWords method. Assume that each of its two parameters is a String of length two or more. public void processWords(String word1, String word2) { String str1 = word1.substring(0, 2);  String str2 = word2.substring(word2.length() - 1); String result = str2 + str1; System.out.println(result.indexOf(str2)); } 2.  2020  Which of the following best describes the value printed when processWords is called? (A) The value 0 is always printed. (B) The value 1 is always printed. (C) The value result.length() - 1 is printed. (D) A substring containing the last character of word2 is printed. (E) A substring containing the last two characters of word2 is printed. 3. Which of the following statements assigns a random integer between 25 and 60, inclusive, to rn? (A) int rn = (int) (Math.random() * 25) + 36; (B) int rn = (int) (Math.random() * 25) + 60; (C) int rn = (int) (Math.random() * 26) + 60; (D) int rn = (int) (Math.random() * 36) + 25; (E) int rn = (int) (Math.random() * 60) + 25; 4. Vehicles are classified based on their total interior volume. The classify method is intended to return a vehicle classification String value based on total interior volume, in cubic feet, as shown in the table below. Vehicle size class Total interior volume Minicompact Less than 85 cubic feet Subcompact 85 to 99 cubic feet Compact 100 to 109 cubic feet Mid-Size 110 to 119 cubic feet Large 120 cubic feet or more The classify method, which does not work as intended, is shown below. public static String classify(int volume) 2020 The classify method works as intended for some but not all values of the parameter volume. For which of the following values of volume would the correct value be returned when the classify method is executed?  (A) 80 (B) 90 (C) 105 (D) 109 (E) 115 5. Which of the following best describes the value of the Boolean expression shown below? a && !(b || a) (A) The value is always true. (B) The value is always false. (C) The value is true when a has the value false, and is false otherwise. (D) The value is true when b has the value false, and is false otherwise. (E) The value is true when either a or b has the value true, and is false otherwise. 6. Consider the following code segment. int val = 48; int div = 6; while ((val % 2 == 0) && div > 0) { if (val % div == 0) { System.out.print(val + " "); } val /= 2; div--; } 2020 (A) 48 12 6 (B) 48 12 6 3 (C) 48 12 6 3 1 (D) 48 24 12 6 (E) 48 24 12 6 3 Consider the following class definition.  7. (A) private int getX() (B) private void getX() (C) public int getX() (D) public void getX() (E) public void getX(int x) In the following code segment, assume that the string str has been properly declared and initialized. The code segment is intended to print the number of strings in the array animals that have str as a substring.  8. 2020  (A) The Boolean expression in the for loop header should be changed to i < animals.length. (B) The Boolean expression in the for loop header should be changed to i < animals.length -1. (C) The Boolean expression in the for loop header should be changed to i < animals[i].length. (D) The condition in the if statement should be changed to animals[i].equals(str). (E) The condition in the if statement should be changed to animals[i].substring(str). 9. Consider an integer array, nums, which has been declared and initialized with one or more integer values. Which of the following code segments updates nums so that each element contains the square of its original value? I. II. III. for (int k = 0; k < nums.length; k++) { nums[k] = nums[k] * nums[k]; } for (int n : nums) { n = n * n; } (A) II only (B) I and II only (C) I and III only (D) II and III only (E) I, II, and III 10. Consider the following code segment.  2020  Which of the following represents the contents of numbers after the code segment has been executed? (A) ["one", "four", "five"] (B) ["three", "two", "five"] (C) ["three", "four", "two"] (D) ["three", "four", "five"] (E) ["one", "two", "three", "four", "five"]   11. Consider the following method, which is intended to return a list containing the elements of the parameter myList with all even elements removed. Which of the following best explains why the code segment does not work as intended? (A) The code segment causes an IndexOutOfBoundsException for all lists because of an incorrect Boolean expression in the for loop. (B) The code segment causes an IndexOutOfBoundsException for lists with at least one even element because the indexes of all subsequent elements change by one when a list element is removed. (C) The code segment returns a list with fewer elements than intended because it fails to consider the last element of myList. (D) The code segment removes the wrong elements of myList because the condition in the if statement to test whether an element is even is incorrect. (E) The code segment skips some elements of myList because the indexes of all subsequent elements change by one when a list element is removed. 12. Consider the following code segment. int[][] points = {{11, 12, 13, 14, 15}, {21, 22, 23, 24, 25}, {31, 32, 33, 34, 35}, {41, 42, 43, 44, 45}}; for (int row = 0; row < points.length; row++) { for (int col = points[0].length - 1; col >= row; col--) 2020 (A) 15 25 35 45 14 24 23 34 33 32 44 43 42 41 (B) 15 14 13 12 25 24 23 35 34 45 (C) 11 21 31 41 12 13 14 15 22 23 24 32 33 42 (D) 15 25 35 45 14 13 12 11 24 23 22 34 33 44 (E) 15 25 35 45 14 24 34 44 13 23 33 43 12 22 32 42 11 21 31 41 13. Consider the following code segment. int[][] arr = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}}; int sum = 0; for (int[] x : arr) { for (int y = 0; y < x.length - 1; y++) { sum += x[y]; } } (A) 36 (B) 54 (C) 63 (D) 68 (E) 78 2020 14. Consider the following class definitions. public class Thing1 { public void calc(int n) { n *= 3; System.out.print(n); } } public class Thing2 extends Thing1 { public void calc(int n) { n += 2; super.calc(n); System.out.print(n); } } What is printed as a result of executing the code segment? (A) 4 (B) 6 (C) 68 (D) 124 (E) 1212 15. Consider the following two methods, which are intended to return the same values when they are called with the same positive integer parameter n. public static int mystery1(int n) { if (n > 1) {   return 5 + mystery1(n - 1); } else {   return 1; } } 2020  (A) The variable total should be initialized to 1. (B) The variable x should be initialized to 0. (C) The condition in the while loop header should be x < n - 1. (D) The condition in the while loop header should be x <= n. (E) No change is required; the methods, as currently written, return the same values when they are called with the same positive integer parameter n. 2020