Do something like
Switch the xxxx's with your item id's, then addCode:public static final int[] UNTRADEABLE_ITEMS = {xxxx,xxxx,xxxx};
Then just add a check for whether or not it's tradeable where ever your server handles tradingCode:public boolean tradeable(int itemId) { for (int j = 0; j < UNTRADEABLE_ITEMS.length; j++) { if (itemId == UNTRADEABLE_ITEMS[j]) return false; } return true; }