How can I make a block only drop a item if your breaking it with a certain tool?

Hi

 

This link talks about mining in a lot of detail, including drops

http://greyminecraftcoder.blogspot.co.at/p/list-of-topics.html

(see the 3 links under "Mining Blocks With Tools", especially this one

http://greyminecraftcoder.blogspot.ch/2015/01/mining-blocks-with-tools.html near the end

 

Short answer - it depends on whether the block is custom, your item is custom, or both are vanilla.  Your best bet is probably

Block.getDrops()

or

Item.onBlockDestroyed()

or

BlockEvent.HarvestDropsEvent

 

-TGG