求两个字符串的最大公共字串

public class Test
  {
   public String search(String s1,String s2)
    {
  String max = "" ;
   for ( int i = 0 ; i < s1.length(); i ++ )
    {
     for ( int j = i + 1 ; j <= s1.length(); j ++ )
      {
      String sub = s1.substring(i,j);
       if ((s2.indexOf(sub) != - 1 ) && sub.length() > max.length())
        {
        max = sub;
      }
    }
  }
   return max;
  }
  
   public static void main(String[] args)
    {
    String s1 = " abedafghigj " ;
    String s2 = " xyzabfddfigj " ;
    String output = new Test().search(s1,s2);
    System.out.println(output);
  }
}