code: public static String searchAndReplace(String s, String src, String dst)
    {
      if(s == null)
        return null;
  
      StringBuilder result = new StringBuilder();
  
      int i = 0;
      int len = s.length();
      int len2 = src.length();
  
      while(i < len)
      {
        int index = s.indexOf(src, i);
        if(index == -1)
        {
          if(i == 0)
            return s;
  
          result.append(s.substring(i));
          break;
        }
  
        result.append(s.substring(i, index));
        result.append(dst);
  
        i = index + len2;
      }
  
      return result.toString();
    }
docs: Searches in the string '<code>s</code>' all occurences of the
  substring '<code>src</code>' and replaces it with the string
  '<code>dst</code>'.
  
  @param s the string to search
  @param src the substring to search for inside s
  @param dst the replacing string
  @return the string with the text replaced