Creating lists of players is a bad idea. Store a list of player names instead, then get players from the names with Bukkit.getPlayer(name). To...
You may want to use player.updateInventory(), I've had issues in the past with items not disappearing and sometimes that fixes it.
Also, I would personally use removeItem(itemstack) instead of remove(itemstack).
I'm a bit confused about getMaterial(Material mat). Your matname hashmap is using integers as keys, so it should actually be getMaterial(int x)...
You have code outside your oncommand method to do all the sign stuff when some event (player chat, maybe?) does something with "/stopj1". But...
Entity doesn't have a damage method, because entities can include Snowballs and things without health. Check if the entity is an instance of...
I'm not quite sure you can do that with a plugin, but you can edit your server startup script to delete those files for you. Make it go into your...
Separate names with a comma.
