Java OCA OCP Practice Question 2467

Question

Given: 

3. import java.util.*;  
4. public class Main implements Comparator<Main> {  
5.   int dishSize;  
6.   public static void main(String[] args) {  
7.     Main[] va = {new Main(40), new Main(200), new Main(60)};  
8.   /*from www .  j  av  a 2  s .  c o m*/
9.     Arrays.sort(va, va[0]);  
10.     int index = Arrays.binarySearch(va, new Main(40), va[0]);  
11.     System.out.print(index + " ");  
12.     index = Arrays.binarySearch(va, new Main(80), va[0]);  
13.     System.out.print(index);    
14.   }  
15.   public int compare(Main a, Main b) {  
16.     return b.dishSize - a.dishSize;  
17.   }  
18.   Main(int d) { dishSize = d; }  
19. }

What is the result?

  • A. 0 -2
  • B. 0 -3
  • C. 2 -1
  • D. 2 -2
  • E. Compilation fails.
  • F. An exception is thrown at runtime.


D is correct.

Note

The compare() method has swapped the normal ordering, so "arrays of Main" sort in descending sequence.

Second, of course, is that when binarySearch() can't find an element it returns (-(insertion point) -1) to indicate where the element would have been placed if it had been found.

Note that on line 9, we're sorting based on a Comparator (the 2nd argument).




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