Leetcode 28. Implement strStr() (Java)

题目：

Implement strStr().
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Example 1:
Input: haystack = “hello”, needle = “ll”
Output: 2

Example 2:
Input: haystack = “aaaaa”, needle = “bba”
Output: -1

Clarification:
What should we return when needle is an empty string? This is a great question to ask during an interview.
For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C’s strstr() and Java’s indexOf().

class Solution {
    public int strStr(String haystack, String needle) {
        if(haystack==null){
            return 0;
        }
        char[] hArray = haystack.toCharArray();
        char[] nArray = needle.toCharArray();
        int i=0;
        int j=0;
        while(i<hArray.length && j<nArray.length){
            if(hArray[i]==nArray[j]){
                i++;
                j++;
            }else{
                i=i-j+1;
                j=0;
            }
        }
        if(j==nArray.length){
            return i-j;
        }
        return -1;
    }
}

第一次提交，红框部位计算错误，导致结果有误