Java OCA OCP Practice Question 2649

Question

Given: 

1. import java.util.*;  
2. public class Main {  
3.   public static void main(String[] args) {  
4.     Map<String, String> hm = new HashMap<String, String>();   
5.     String[] k = {null, "2", "3", null, "5"};   
6.     String[] v = {"a", "b", "c", "d", "e"};  
7.   // w ww  . ja v a2  s.  c  om
8.     for(int i=0; i<5; i++) {  
9.       hm.put(k[i], v[i]);  
10.       System.out.print(hm.get(k[i]) + " ");  
11.     }  
12.     System.out.print(hm.size() + " " + hm.values() + "\n");  
13.  } }

What result is most likely?

  • A. a b c a e 4 [c, b, a, e]
  • B. a b c d e 4 [c, b, a, e]
  • C. a b c d e 4 [c, d, b, e]
  • D. a b c, followed by an exception.
  • E. An exception is thrown with no other output.
  • F. Compilation fails due to error(s) in the code.


C is correct.

Note

It's legal for a HashMap to have one null key, and if you invoke put() using an existing key, the new value replaces the old value.

The values() method does NOT guarantee any ordering.




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