Question

I am trying to find a value in an array and I know for sure that this value will exist only once, so i am trying to find the value and return the index of the array where it is stored, if not found return -1
This is what I am trying to do:

static Integer[] accs = new Integer[20];
 public static int search()
    {
        Integer[] numbers;
        numbers = accs;
        Integer key;
        Scanner sc = new Scanner(System.in);
         System.out.println("Enter the Account Number:");        
         key = sc.nextInt();

        for (Integer index = 0; index < numbers.length; index++)
      {
           if ( numbers[index] == key )
                 return index;  //We found it!!!
      }
     // If we get to the end of the loop, a value has not yet
     // been returned.  We did not find the key in this array.
     return -1;

    }

When I run this even though I know that the value exists in the array, nothing is being displayed. I debugged and then I found out that the Key variable is not having the value of what I typed. Is something wrong there?

Answer 1

Your array is storing Integer, which is a java Object, to test for equality of Java Object you need to call Object.equals method instead of ==.

In your case I suggest you use an array of int instead of Integer, it is lighter in memory, support == and you are not using any of the features of Integer so you don’t need them here.