LeetCode - Longest Common Prefix

package string;

public class LongestCommonPrefix {

    public String longestCommonPrefix(String[] strs) {
        int len = 0;
        if (strs == null || (len = strs.length) == 0) return "";

        StringBuilder sb = new StringBuilder();
        int i = 0;
        int len0 = strs[0].length();
        while (i < len0) {
            char c = strs[0].charAt(i);
            for (int j = 1; j < len; ++j) {
                if (i >= strs[j].length() || strs[j].charAt(i) != c)
                    return sb.toString();
            }
            
            sb.append(c);
            ++i;
        }
        
        return sb.toString();
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String[] strs = { "abc", "ab", "abcd", "abcdef" };
        LongestCommonPrefix l = new LongestCommonPrefix();
        System.out.println(l.longestCommonPrefix(strs));
    }

}