Algorithm Implement of Searching - Binary Search

public class Searching {

    /* Binary Search */

    public static int search(String key, String[] a) {
        return search(key, a, 0, a.length);
    }

    /** binary search implement
      * key string sourght
      * a[] sorted list of strings
      * lo smallest possible index
      * hi-1 largest possible index
      * */
    public static int search(String key, String[] a, int lo, int hi) {

        if (hi <= lo) return -1;
        int mid = lo + (hi-lo)/2;
        int cmp = a[mid].compareTo(key);
        if      (cmp > 0) return search(key, a, lo, mid);
        else if (cmp < 0) return search(key, a, mid+1, hi);
        else              return mid;
    }

    /* Sequence searching algorithm */
    public static int searchSequence(String key, String[] a) {
        int N = a.length;
        for (int i = 0; i < N; i++)
            if (a[i].compareTo(key) == 0)
            return i;
        return -1;
    }

    /* Exception filter. Read a sorted list of strings from a whitelist file,
     * then print out all strings from standard input not in the whitelist.
     */
    public static void main(String[] args) {
        In in = new In(args[0]);
        String s = in.readAll();
        String[] words = s.split("\\s+"); // Separated by "whitesapce"
        while (!StdIn.isEmpty()) {
            String key = StdIn.readString();
            if (search(key, words) == -1)
                System.out.println(key);
        }
    }
}