Help with Item detection

Hey,
my problem is, that i want a listener who check if a specfic item is laying on a specfic block and than do something with that item. Or the same on the other hand, if under an item is a specific block and do something with that item.
The reason for that is to detect a specfic order of blocks and if an item is laying on it it does something like ritual. (For Spigot 1.14)

 

@Krippi

1. Listen to ItemSpawnEvent or PlayerDropItemEvent to get when an item is dropped.
2. If the item is equal to the one you want to check for, create a new BukkitRunnable that repeats every second.
3. Inside the runnable, do a check to determine if the item is on the ground. If it is, check if the block below it is a specific block. If it is, look for the other blocks.

 

@Zombie_Striker
isnt it possible to create a listener that checks if an item is on the ground?
Instead of using a BukkitRunnable.