I am having some trouble iterating over every furnace recipe and assigning a recipe to each recipe. It is meant to assign the output of the recipe as the output of the smelting recipe one of the inputs as the item being smelted. Here is the code I have. The print line is for debugging and only prints "null". Any suggestions are welcome.

 

 

Map smeltList = FurnaceRecipes.instance().getSmeltingList();

for (int i = 0; i < smeltList.size(); i++) {

System.out.println(smeltList.get(i));

}

 

FurnaceRecipes#getSmeltingList

returns a

Map<ItemStack, ItemStack>

, i.e. a

Map

with

ItemStack

keys and

ItemStack

values. Calling

Map#get

on this with an

int

will always return

null

because it doesn't have

int

keys.

 

You can't iterate over a

Map

directly, you must iterate through either its entry set, key set or values collection (obtained by calling the corresponding

Map

methods). All of these return an object that implements

Iterable

, so you can either iterate through them with an enhanced for/for-each loop or by using the

Iterator

.

 

When iterating a collection with an enhanced for loop, you can't modify the collection at all. When iterating with an

Iterator

, you can remove the current value by calling

Iterator#remove

but you can't add new values.

 

This is basic Java knowledge that you should already have before making a mod.

When I learnt Java I didn't read anything about "enhanced for" loops. I will research about them and then tell you the results! 

FurnaceRecipes#getSmeltingList

returns a

Map<ItemStack, ItemStack>

, i.e. a

Map

with

ItemStack

keys and

ItemStack

values. Calling

Map#get

on this with an

int

will always return

null

because it doesn't have

int

keys.

 

You can't iterate over a

Map

directly, you must iterate through either its entry set, key set or values collection (obtained by calling the corresponding

Map

methods). All of these return an object that implements

Iterable

, so you can either iterate through them with an enhanced for/for-each loop or by using the

Iterator

.

 

When iterating a collection with an enhanced for loop, you can't modify the collection at all. When iterating with an

Iterator

, you can remove the current value by calling

Iterator#remove

but you can't add new values.

 

This is basic Java knowledge that you should already have before making a mod.

 

Thank you so much! It worked after I did a quick Google search. The whole problem was mainly the way that I couldn't work out how to iterate over a set properly, so I ignored it. This is how I did it after.

 

 

Set smeltList = FurnaceRecipes.instance().getSmeltingList().keySet();

for (Object in: smeltList) {

GameRegistry.addShapelessRecipe(FurnaceRecipes.instance().getSmeltingResult((ItemStack) in), furnace, (ItemStack) in);

}

 

Don't use raw types (e.g.

Set

).

FurnaceRecipes.instance().getSmeltingList().keySet()

returns a generic type (

Set<ItemStack>

), so refer to it as that type.

 

Iterating over the keys and using

FurnaceRecipes#getSmeltingResult

to get the smelting result is extremely inefficient since you're now iterating through the smelting list again for every entry.

 

Either look up the

ItemStack

key directly in the

Map

or iterate over the entries so you have direct access to the key and value.

Don't use raw types (e.g.

Set

).

FurnaceRecipes.instance().getSmeltingList().keySet()

returns a generic type (

Set<ItemStack>

), so refer to it as that type.

 

Iterating over the keys and using

FurnaceRecipes#getSmeltingResult

to get the smelting result is extremely inefficient since you're now iterating through the smelting list again for every entry.

 

Either look up the

ItemStack

key directly in the

Map

or iterate over the entries so you have direct access to the key and value.

 

Is this more efficient? It might not be what you were telling me, but this seems to work too.

 

 

Map smeltList = FurnaceRecipes.instance().getSmeltingList();

Set<ItemStack> smeltSet = smeltList.keySet();

for (ItemStack in: smeltSet) {

GameRegistry.addShapelessRecipe((ItemStack) smeltList.get(in), furnace, in);

}

 

That's the first alternative I suggested, it's more efficient than using

FurnaceRecipes#getSmeltingResult

. It's probably slightly less efficient than iterating through the entries rather than the keys (since it needs to look up the value of the key in the map), but not by a large amount.

 

You're still using raw types:

FurnaceRecipes#getSmeltingList()

returns a

Map<ItemStack, ItemStack>

, not a

Map

.

That's the first alternative I suggested, it's more efficient than using

FurnaceRecipes#getSmeltingResult

. It's probably slightly less efficient than iterating through the entries rather than the keys (since it needs to look up the value of the key in the map), but not by a large amount.

 

You're still using raw types:

FurnaceRecipes#getSmeltingList()

returns a

Map<ItemStack, ItemStack>

, not a

Map

.

 

*facepalm* I forgot to change the Map to be Map<ItemStack, ItemStack> . Nevermind, I have changed that now! Thanks for your advice.