Question

 

The following code was meant to print out the elements in an array in reverse order. However, it does not behave correctly.

public static void reverse(int[] a, int index) {

      if (index == (a.length - 1))

        System.out.printf("%d%n", a[index]);

      else {

         reverse(a, index);

1. What does it do? Explain why it behaves in this way.                                 

 

2. There is more than one error in the code. Correct the code so that it will recursively print out the elements of the array in reverse order. Highlight your changes clearly (in bold with yellow highlight).                                                                                                                               

                                                                                                                               

3. Complete the following main method to show how you would invoke your corrected reverse method to test that it now works correctly.                                                        (1 mark)

 

 

   public static void main(String[] args) {

        int [] array = { 1, 2, 3, 4, 5 };

        //Part c: call reverse to print array in reverse order

       

    }

4. Write a generic version of the corrected recursive reverse method that could be used to print any of the following arrays (or arrays of other reference types) in reverse order.

Integer[] integerArray = {1,2,3,4,5,6};

   Double[] doubleArray = {1.1, 2.2, 3.3, 4.4, 5.5, 6.6};

   String[] numbers = {"one", "two", "three", "four", "five", "six"};

 

Answer 1

Answer 1:

Here we are not printing reversly as we printing at before resurvice cal only thats it will not print reveser:

public static void reverse(int[] a, int index) {

       // we should check till length

// Answer 2
       if (index == (a.length))
           return;
       reverse(a, index+1);

// Answer 3:
       // we should print after recursive call
       System.out.printf("%d%n", a[index]);

   }

Answer 4:

// we should pass index as 0

reverse(array, 0);