How to set a timer so every time the player right click an item start and when it get to a specific value something happens

For items, you cannot add a timer directly to the Item class due to the fact there is only 1 item instance of each item you declare, so you need to store any mutable information in the ItemStack NBT tag.

 

For a timer, you have two options: actually use a ticking timer that needs updating each tick, OR set one time value that is X ticks in the future, and check for when the world time reaches it. The second is nice because it avoids the NBT update - when the ItemStack NBT updates, it usually causes a rendering 'glitch'.

 

So:

1. Override Item#onItemRightClick

    a. Add an NBTTagCompound to the ItemStack given if it doesn't already have one

    b. Set a Long value (that's what Minecraft time uses) in the tag with world.getWorldTime() + X, where X is number of ticks (20 ticks = 1 second)

 

2. Override Item#onUpdate

    a. Check if the ItemStack in question has an NBTTagCompound and the correct tag (and the value is > 0)

    b. If so, check if the current world time is >= the value stored in the tag

    c. If so, do whatever you wanted to do, and either remove the time tag or set it back to zero