Minecraft ask if inventory slot is full of 64 blocks?

So I would like to know how to query whether an inventory slot contains 64 blocks and then execute a command

In a particular slot or in general?

A certain one

Then unfortunately I have no idea, only in general in the inventory.

Tell me your idea in the inventory

If (p.getInventory (). Contains (material)) // Guess I don't know if that's right.

No, because I modde and therefore do not want to use player p

I see