Changing Anvilled Item

I want to change the output of an anvilled item, how would I do that?

 

The API for anvils is not that great.
This is what I used in one of my plugins:

Code:

@EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
  public void onInventoryClick(InventoryClickEvent e)
  {
      if (e.getInventory().getType().equals(InventoryType.ANVIL))
      {
        if(e.getWhoClicked() instanceof Player)  // probably not necessary, but to be safe...
        {
            final Player player = (Player) e.getWhoClicked();         
 
            if(e.getSlotType() == SlotType.RESULT)
            {
              if((e.getCursor().getType() == Material.AIR) && (e.getCurrentItem().getType() != Material.AIR)) // player will take the resulting item
              {
                  // check if item in RESULT slot is the wanted type (by using .getContents() and checking the item in slot index 2 (RESULT slot should be index 2, but better double check this)
                  // clear the result slot
                  // call e.getInventory().setItem(2, myItemStack) so the player will pick up the new item
                  // or call player.getInventory().addItem(myItemStack) to add the new item directly to the players inventory
              }
            }       
        }
      }
  }

I've not tested the part which is in comments. But it should at least give your the idea.

 

Awesome, thanks.