Unit 4 AP CSA Review

What is output by the following code?

• iahbgcfd → This loop will interleave the characters of str1 and str2, starting with the end of str2 and start of str1. The loop will only interleave 4 sets of characters, because str1.length() == 4. This prevents the e in str2 from being printed

• aibhcgdf → If the order of the print statements were reversed, then this would be the correct output

• ibhcgde → The a should be included in the output, and the e should be excluded. See choice a

• Index out of Bounds Error → If we were checking the condition j >= 0, then we’d have an index out of bounds error

• iahbgcfde → There should be no e at the end of the output. The loop ends before it prints the e

Which of the following statements will return a random even number between 6 and 14 inclusive?

• 6 + 2 * (int) (4 * Math.random())

• 6 + (int) (8 * Math.random())

• 4 + 2 * (int) (5 * Math.random())

• (int) (Math.random() * 14) - 6

• 6 + 2 * (int) (5 * Math.random())

Choose which three values should replace the blanks in the for loop so that it loops through the numbers: 1 3 5 7 9. Note that the choices will fill in the three blanks in the order in which they appear.

• 1, <10, +=2

• 1, <9, ++

• 0, <10, ++

• 1, <=9, ++

• 0, <9, +=2

What does short circuit evaluation mean in the following code?

• if a < b is false, then c != d is not evaluated

• if a < b is true then c != d is not evaluated

• if c != d is false, then a < b is not evaluated

• if c != d is true, then a < b is not evaluated

• if a < b is false, then c != d is evaluated

Which of the following code segments will print all numbers divisible by 5 between 1 and 50 in ascending order?

• I only

• II and III only

• II only

• I and II only

• I, II and III

Assume that x and y are boolean variables and have been properly initialized. Which of the following best describes the result of evaluating the expression (x && y) || !(x || !y)?

• true only when x and y have the same value

• true only when y is true

• true only when x is true

• Always false

• Always true

Consider the following output: 4 3 2 1 3 2 1 2 1 1 Which of the following code segments will produce this output?

Which of the following code segments prints the number of times the code substring “ab” appears in the String str?

• int count = 0; for (int i = 2; i <= str.length(); i++) { if (str.substring(i - 2, i).equals("ab")) { count += 1; } } System.out.println(count);

• int count = 0; for (int i = 1; i <= str.length(); i++) { if (str.substring(i - 1, i).equals("ab")) { count += 1; } } System.out.println(count);

• int count = 0; for (int i = 0; i < str.length(); i += 2) { if (str.substring(i, i + 2).equals("ab")) { count++; } } System.out.println(count);

Which of the following would print the numbers: 94 73 52 31

• c. I and II only

• e. I only

• b. I, II and III

• I. for (int t = 94; t > 30; t -= 21) { System.out.print(t + " "); } II. int t = 115; while (t > 31) { t -= 21; System.out.print(t + " "); } III. int t = 94; while (t > 31) { System.out.print(t + " "); t -= 21; }

• a. II only

Consider the following code segment. for (int n = 1; n < 20; n += 7) { for (int k = n; k < n + 5; k++) { if (k % 2 == 0) { System.out.print(k + " "); } } System.out.println(); } What will be printed as a result of executing the code segment?

• 10 12

• 8 10 12

• 2 4 6

• 2 4

• 16 18