查找数组指定元素，数组中包含“”

package com.Proxy;

/**
 * @author Ruth
 * created on 7/29/2018
 * There is an array which is sorted and contains "", check the specified elements in this array, return the index;
 */
public class TestArray {

  public static void main(String[] args) {

    String[] arr = {"A", "B", "", "", "", "C"};
    int index = getIndexOfChar(arr, "C");

    System.out.println(index);

  }

  public static int getIndexOfChar(String[] arr, String str) {
    if (arr == null || arr.length == 0 || str == null) {
      return -1;
    }

    int left = 0;
    int right = arr.length - 1;
    int res = -1;

    int mid = 0;
    int i = 0;
    while (left <= right) {
      mid = (left + right) / 2;
      if (arr[mid] != null && str.equals(arr[mid])) {
        res = mid;
        right = mid - 1;
      } else if (arr[mid] != null) {
        if (arr[mid].compareTo(str) > 0) {
          right = mid - 1;
        } else {
          left = mid + 1;
        }
      } else {
        i = mid;
        while (arr[i] == null && --i >= left) ;
        if (i < left || arr[i].compareTo(str) < 0) {
          left = mid + 1;
        } else {
          res = arr[i].equals(str) ? i : res;
          right = i - 1;
        }
      }
    }

    return res;

  }

}