string match

1. Use the java method to find

class Solution {    public:        int strStr(string haystack, string needle) {            return haystack.find(needle);        }    };

2. 

public class Solution {  
    public String longestCommonPrefix(String[] strs) {  
        if(strs.length==0)return "";  
        char[] str=strs[0].toCharArray();  
        int Min=str.length;  
        for(int i=1;i<strs.length;i++){  
            char[] s=strs[i].toCharArray();  
            int j=0;  
            while(j<Min && j<s.length && s[j]==str[j])j++;  
            Min = Min> j? J: Min;  
        }  
        return strs[0].substring(0,Min);  
    }  
}