binarysearch.java

public static int binarySearch(int [] phoneBook, int number) {
      int mid, low, high;

      low = 0;
      high = phoneBook.length - 1;

      while (high >= low) {
          mid = (high + low) / 2;
          if (phoneBook[mid] < number) {
              low = mid + 1;
          }
          else if (phoneBook[mid] > number) {
              high = mid - 1;
          }
          else {
              return mid;
          }
      }
			return -1; // If not found
  }