LeetCode-Implement strStr()

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

public class Solution {
    public int strStr(String haystack, String needle) {
        int h=haystack.length();
        int n=needle.length();
        for(int i=0; i<=h-n; i++){
            int j;
            for(j=0; j<n; j++){
                if(needle.charAt(j) != haystack.charAt(i+j)){
                    break;
                }
            }
            if(j == n){
                return i;
            }
        }
        return -1;
    }
}