[1.12.2] Capabilities boggling mind

[FrostBytes]

I didn't really understand the Forge Capabilities docs and I was asking if someone could help me digest the information.
Things I understand:
Capabilities provide a way to save data, like energy or inventories.
How am I supposed to change data about a tile entity using capabilities? I understand how to create a custom capability, but after that I was lost.

[FrostBytes]

5 hours ago, diesieben07 said:

What kind of data do you want to change? It would help if you could explain what you are actually trying to achieve.

I’m not trying to achieve anything atm. I just want to know what I can do with it and how. I just want someone to break down some of the information provided in the documents because I don’t really understand it. But, because it will be a complete waste of time rewording everything, lets just say I want to make power levels for an item. This item carrys only a single integer that cannot be higher than 20. How would I implement the capability system to do such thing?

Edited March 5, 2019 by FrostBytes
very vague comment

[Cadiboo]

Capabilities are a better way of achieving the same thing as Interfaces.

Interface way:

if (tileEntity instanceof IThing)

Capability way

if (tileEntity.hasCapability(ThingCapability))

Interface way:

((IThing)tileEntity).doThing();

Capability way

tileEntity.getCapability(ThingCapability).doThing();

 

Interfaces make your tile be something while Capabilities let your tile provide something. Capabilities follow the OOP concept of "Composition over Inheritance".