I haven't researched NBT much, however I was wondering whether it would be possible to store a custom Java object(not minecraft object, like an instance of a java class) as NBT to an item? How would I go about doing this, can anyone help, or provide any pages that may cover this?

I have had a quick look around and I cannot find anyway of storing custom data types as NBT. I want to be able to store my custom data type in game however it should exist only once and on server side

You need to break down your object and the objects it's composed of into the basic data types supported by NBT: compound tags for complex objects, list tags for collections, string tags for strings, numeric tags for numbers and numeric array tags for collections of numbers. You should implement

INBTSerializable

on classes that can be serialised to NBT.

 

To attach data to an

ItemStack

,

Entity

or

TileEntity

(or any other

ICapabilityProvider

), use the Capability system.

 

To attach data to a dimension or save, use World Saved Data.