Recursive Binary Search

Recursive Binary Search

   public class BinarySearchRecursive
   {
     public static final int NOT_FOUND = -1;
     /**
     * Performs the standard binary search
     * using two comparisons per level.
     * This is a driver that calls the recursive method.
     * @return index where item is found or NOT_FOUND if not found.
     */
     public static int binarySearch( Comparable [ ] a, Comparable x )
     {
       return binarySearch( a, x, 0, a.length -1 );
     }
     /**
     * Hidden recursive routine.
     */
     private static int binarySearch( Comparable [ ] a, Comparable x,int low, int high )
     {
       if( low > high )
         return NOT_FOUND;
       int mid = ( low + high ) / 2;
       if( a[ mid ].compareTo( x ) < 0 )
         return binarySearch( a, x, mid + 1, high );
       else if( a[ mid ].compareTo( x ) > 0 )
         return binarySearch( a, x, low, mid - 1 );
       else
         return mid;
     }
     // Test program
     public static void main( String [ ] args )
     {
       int SIZE = 8;
       Comparable [ ] a = new Integer [ SIZE ];
       for( int i = 0; i < SIZE; i++ )
         a[ i ] = new Integer( i * 2 );
    
       for( int i = 0; i < SIZE * 2; i++ )
         System.out.println( "Found " + i + " at " +
           binarySearch( a, new Integer( i ) ) );
     }
   }