Question 5 Closest Element to target

/*
key: find two element, one is larger or equal, the other is smaller or equal
*/

public class Solution {
  public int closest(int[] array, int target) {
    // Write your solution here
    // corner case
    if (array == null || array.length == 0) {
      return -1;
    }
    int left = 0; 
    int right = array.length - 1;
    while (left < right - 1) {
      int mid = left + (right - left) / 2;
      if (array[mid] == target) {
        return mid;
      }
      else if (array[mid] < target) {
        left = mid;
      }
      else {
        right = mid;
      }
    }
    if (Math.abs(array[left] - target) < Math.abs(array[right] - target)) {
        return left;
      }
    return right;
  }
}