HashMap<String, ItemStack[]> inventoryContents = new HashMap<String, ItemStack[]>();
HashMap<String, ItemStack[]> inventoryArmorContents = new HashMap<String, ItemStack[]>();
inventoryContents.put(player.getName(), player.getInventory().getContents());
inventoryArmorContents.put(player.getName(), player.getInventory().getArmorContents());
if(inventoryContents.containsKey(player.getName() && inventoryArmorContents.containsKey(player.getName())){
player.getInventory().clear();
player.getInventory().setContents(inventoryContents.get(player.getName()));
player.getInventory().setArmorContents(inventoryArmorContents.get(player.getName());
}