Trying to update AutoReplace to keep near broken items

Hello

I am a java noob, these are my first lines ever. Have knowledge of PHP but no OO.

Anyway this is my code thus far:

Code:

public class ToolReplaceListener implements Listener {
    @EventHandler
    public void DetectDurability(BlockBreakEvent event){
        Player player = event.getPlayer();
        PlayerInventory inv = player.getInventory();
        Material tool = Material.getMaterial(inv.getItemInHand().getTypeId());
        ItemStack itemInHand = player.getItemInHand();
        //if item is nearly destroyed
        if(!tool.isBlock() && inv.getItemInHand().getDurability() == tool.getMaxDurability() - 1) {
            event.getPlayer().sendMessage(ChatColor.RED+"Almost destroyed.");
            //save item and the durability
            int durability = itemInHand.getDurability();
            int slot = inv.getHeldItemSlot();
            int ID = inv.getItemInHand().getTypeId();
            ItemStack[] items = inv.getContents();
            for (int i = 0; i < items.length; i++) {
                if (i != slot) {
                    ItemStack obj = items[i];
                    //for each item in inventory, check if it's what we want, then we can break
                    if ((obj == null) || (obj.getTypeId() != ID) || (obj.getAmount() <= 0))
                        continue;
                    //set current item in hand to replacement (in effect replacing with new full durability)
                    inv.getItemInHand().setDurability((short)(obj.getDurability() - 1));
                    inv.addItem(obj.setDurability((short) durability));
                    inv.clear(i);
                    break;
                }
            }
        }
    }
}

This is the line with the problem

Code:

inv.addItem(obj.setDurability((short) durability));

I could not find any sort of move item within inventory so thoughts were set current near broken item to full durability, delete the full one from inventory (replacement) then add a new one with current ones damage value (current in hand item that's near broken). If that makes sense?