Java OCA OCP Practice Question 591

Question

Given: 

 3. import java.util.*;
 4. public class Main {
 5.   public static void main(String[] args) {
 6.     String[] s = {"map", "pen", "marble", "key"};
 7.     MyClass o = new MyClass();
 8.     Arrays.sort(s,o);// ww w  .  j a v a  2 s  .co  m
 9.     for(String s2: s) System.out.print(s2 + " ");
10.     System.out.println(Arrays.binarySearch(s, "map"));
11.   }
12.   static class MyClass implements Comparator<String> {
13.     public int compare(String a, String b) { return b.compareTo(a); }
14.   }
15. }

Which are true?

Choose all that apply.

  • A. Compilation fails
  • B. The output will contain a 1
  • C. The output will contain a 2
  • D. The output will contain a -1
  • E. An exception is thrown at runtime
  • F. The output will contain "key map marble pen"
  • G. The output will contain "pen marble map key"


D and G are correct.

Note

First, the compareTo() method will reverse the normal sort.

Second, the sort() is valid.

Third, the binarySearch() gives -1 because it needs to be invoked using the same Comparator (o) as was used to sort the array.

Note that when the binarySearch() returns an "undefined result," it doesn't officially have to be a -1, but it usually is, so if you selected only G, you get full credit!




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