public void writeUTF8(String s) {
    int i = 0;
    for(char c : s.toCharArray())
      if(c >= 0x1 && c <= 0x7F)
        i++;
      else if(c == 0x0 || (c >= 0x80 && c <= 0x7FF))
        i += 2;
      else
        i += 3;
    int j = 0;
    byte[] b = new byte[i];
    for(char c : s.toCharArray())
      if(c >= 0x1 && c <= 0x7F)
        b[j++] = (byte)c;
      else if(c == 0x0 || (c >= 0x80 && c <= 0x7FF)) {
        b[j++] = (byte)(((c >> 6) & 0x1F) | 0xC0);
        b[j++] = (byte)((c & 0x3F) | 0x80);
      } else {
        b[j++] = (byte)(((c >> 12) & 0x0F) | 0xE0);
        b[j++] = (byte)(((c >> 6) & 0x0F) | 0x80);
        b[j++] = (byte)((c & 0x0F) | 0x80);
      }
    writeShort(b.length);
    write(b);
  }