Longest Common Prefix

Problem:
Write a function to find the longest common prefix string amongst an array of strings.

Analysis:
Starting from the first char of the first string comparing with the rest. Leetocde 出问题了，strs.length()通不过。

Solution:

1:  public class Solution {  
2:    public String longestCommonPrefix(String[] strs) {  
3:      if(strs.length()==0)  
4:       return "";  
5:      if(strs==null)  
6:       return null;  
7:      String str0=strs[0];   
8:      for(int prefixLen=0;prefixLen<str0.length;prefixLen++)  
9:      {  
10:        char c=str0.charAt(prefixLen);  
11:        for(int j=1;j<strs.length();j++)  
12:        {  
13:          if(strs[j].length()<=prefixLen||strs[j].charAt(prefixLen)!=c)  
14:           return str0.substring(0,prefixLen);  
15:        }  
16:      }  
17:      return str0;  
18:    }  
19:  }