When powering a Hopper that is above a solid block or a container the items are held in place correctly within the Hopper. If however the Hopper is placed above a second Hopper then the second hopper will overpower the redstone signal and suck the items out regardless. This may not be a bug and be functioning as intended however, as Hoppers with containers above them are designed to suck out items.
Screenshot: Powering the 2nd Hopper in the chain as shown is completely ineffective as the 3rd Hopper still takes items out.
EDIT: This has been somewhat fixed in 13w02b by the fact that a powered Hopper now does not take items from above, so powering 2 sequential Hoppers in the chain would create an effective lock. Powering the first or the last Hopper in the chain would also be effective, this bug only occurs in long chains of vertical Hoppers, when trying to create a lock mid way down the stack.
Related issues
is duplicated by
MC-7221
Hopper Locking Not Affecting Other Hoppers
MC-7444
Powering a hopper doesn't make it stop receiving from other hoppers.
MC-7659
Hopper won't stop
MC-7677
Hopper cart issue
MC-7797
The hopper minecart doesn't drop items into a locked hopper but a (non-locked) hopper drops items into locked hoppers
MC-8135
Hopper Transfers to Other Hoppers when Locked
MC-8380
When powered, hoppers don't behave consistently.
MC-8868
Hoppers continue to unload even when powered
MC-9909
Hoppers "ARE" losing items to hoppers below them "EVEN" when top hopper is powered.
MC-10886
Hopper Problem
MC-11140
Hopper bug
MC-11917
Hopper receiving items when it is on
MC-12495
Hopper with redstone does not stop hopper below from pulling items from it.
MC-12658
Powered Hopper still recives items through other Hoppers
MC-14215
Hoppers working when powered
MC-33168
Hopper does a terrible job at locking which breaks 1.5 + item sorters
MC-42022
Hopper absorb item even if it is lock
MC-52771
Hopper Problem
MC-112126
Locked Hoppers don't behave as they are supposed to
MC-117473
Hoppers ignore redstone signal
MC-141438
Hopper improper operation
MC-142130
Hopper lock doesn't work
MC-156232
Hopper Transfering Glitch /w Redstone Torch
MC-192605
Locked hoppers are no longer working
MC-224079
Locked Hopper collects items
Attachments
Comments
migrated
migrated
Can confirm.
I hope this isn't a feature.
migrated
Confirmed in 13w02b.
megascience
Could someone explain this a bit better? The problem is that the hoppers below still take out items despite the hopper above being locked? In that case, that shouldn't be possible. In real world concept, I'd imagine locking a hopper would act as closing up it's outputs and forcing it shut. Whether that is actually how it is thought is another thing, but this behavior definitely defies the lock.
migrated
Yea that is correct Louis. The lower hopper is taking items out of the hopper above it, despite the upper one being locked, thus rendering the lock pointless.
Nathan Adams
Intentional. Powering it merely stops it from sucking items from above or pushing items down, but another hopper/dropper can do what it likes still.
migrated
Dinnerbone, merely making hoppers conductive would fix this. After all, they can somehow allow redstone to float on top of the hole. You say there is nothing to fix. Well, this compromises the most simple of sorting machines and forces minecrafters to use pistons ans minecarts. I don't know what you intend the hopper be used for, but if it is locked, it should be completely locked, not only partially. hogwash.
Torabi
A redstone signal does not "lock" the hopper. It merely stops it from operating, meaning that it no longer pulls items from the space or container above it, and no longer pushes items into the space or container pointed to by its output. Because hoppers are containers, hoppers can pull items from other hoppers, regardless of their operational state.
The primary purpose of hoppers, as far as I can tell, is to give us a way to automatically put items in containers and pull them out. The enables the automatic collection of mob drops and the transportation of items via minecarts. They weren't necessarily intended to make sorting machines, but people will figure out a way that works regardless.
And, to put it simply, it's easier to program the way it is.