A RecipeType is different from a recipe itself. Let's see an example of a recipe to understand it better :

my_recipe.json

{
  "type": "minecraft:smelting",
  "ingredient": {
    "tag": "minecraft:logs_that_burn"
  },
  "result": "minecraft:charcoal",
  "experience": 0.15,
  "cookingtime": 200
}

The file itself define the recipe to get charcoal, the type of this recipe is smelting. A RecipeType can be defined as a group of recipes. This RecipeType is used by the furnace block, but you could create another furnace that also use this recipe type but with different stats.

A RecipeType needs two things to work, a Recipe class and a RecipeSerializer class.

The Recipe class defines the inputs, outputs, how to craft with them and other things. When creating a recipe like the example of the charcoal, it creates an instance of your Recipe class that is used to register to RecipeType.

The RecipeSerializer is used to serialize an object (here it is an instance of your Recipe class which defines a recipe) to a packet, and to deserialize from a packet or a json object to an instance of your Recipe class. The RecipeSerializer helps us create recipes faster without having to instanciate ourself our Recipe class for each recipe we need.

To test if different items in an inventory work as inputs of a recipe and get the expected output, we use the RecipeManager class. It has some usefull method such as getAllOfType returning a map of all the recipes of a certain type with their Identifier or getAllMatches returning a List of recipes usable with the inventory of a ScreenHandler.

The easiest way to add a RecipeType is to use some vanilla classes to save a lot of code. An example of this would be all the abstract classes related to cooking. Theses classes are used for the furnace, the smoker, the blast furnace and even the campfire. If your RecipeType behave the same has a vanilla RecipeType you should first try to extends the used classes if they exist(sometime a RecipeType for a block does't have classes that you can use and it is easier to create your RecipeType from scratch).

• Adding a recipe type
• Adding a cooking recipe type
• Adding a cutting recipe type