In 1.8 I use an event handler to add functionality for an automatic smelting enchantment.

 

 

if (player != null && !player.capabilities.isCreativeMode && EnchantmentHelper.getEnchantmentLevel(this.effectId, player.getHeldItem()) > 0) {
HarvestDropsEvent event = (HarvestDropsEvent) baseEvent;
ItemStack drop = event.drops.size() == 0 ? null : event.drops.get(0);
if (drop != null) {
	ItemStack smeltStack = new ItemStack(drop.getItem(), 1, drop.getMetadata());
	ItemStack smeltResult = FurnaceRecipes.instance().getSmeltingResult(smeltStack);
	if (smeltResult != null) {
		smeltResult.stackSize *= drop.stackSize;
		event.drops.clear();
		event.drops.add(smeltResult);
	}
}
}

This code works only the first time breaking a certain block. After that, nothing drops. For example, the first time breaking an iron ore yielded one iron ingot. Tries after that all yielded nothing. This is done using the HarvestDropsEvent.

Always use itemStack.copy() when editing it. (stacks are mutable)

 

When pulling ItemStack from any kind of registry or something - 1st do something like ItemStack tempStack = stack.copy();

Also:

HarvestDropsEvent event = (HarvestDropsEvent) baseEvent;

Wtf? I really hope you are actually doing it as event, not like this.

And:

ItemStack drop = event.drops.size() == 0 ? null : event.drops.get(0);

drops can be bigger than just size==1 and then you do event.drops.clear(); which clears them all, kinda bad design in my opinion.

Always use itemStack.copy() when editing it. (stacks are mutable)

 

When pulling ItemStack from any kind of registry or something - 1st do something like ItemStack tempStack = stack.copy();

Also:

HarvestDropsEvent event = (HarvestDropsEvent) baseEvent;

Wtf? I really hope you are actually doing it as event, not like this.

And:

ItemStack drop = event.drops.size() == 0 ? null : event.drops.get(0);

drops can be bigger than just size==1 and then you do event.drops.clear(); which clears them all, kinda bad design in my opinion.

This is part of a method called from my event handler. I'll try the .copy() method out.

UPDATE: Worked like a charm! Thanks.