PacketUpdate packet;
switch (packetID) {
case PacketIds.LETTER_INFO:
PacketLetterInfo packetT = new PacketLetterInfo();
packetT.readData(data);
onLetterInfo(packetT);
break;
case PacketIds.POBOX_INFO:
PacketPOBoxInfo packetP = new PacketPOBoxInfo();
packetP.readData(data);