I am adding "undo" functionality to a small Android app that lets you edit some graph. Should I put this on the "back" button? Or somewhere else? What is the best place for this?
2 Answers
You shouldn't do that.
The back button is a navigation element. Check the Core App Quality Guide, and especially the Back Navigation Guide.
Android users will expect the button to navigate back. If you want an undo, add an action to the action bar or provide it via a popup (http://developer.android.com/design/patterns/confirming-acknowledging.html)
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Thanks for the pointer to how to do it the right way. I observed some users using the back button when they had made a mistake (bringing them to the previous screen) -- providing some obvious way to undo will probably prevent this.... Oct 25, 2014 at 18:33
No, it is not ok.
From the Android Developer Guidelines, Providing Proper Back Navigation:
Back navigation is how users move backward through the history of screens they previously visited. All Android devices provide a Back button for this type of navigation, so your app should not add a Back button to the UI.
Android has a clear use pattern for the Back button, which is allowing the user to move back in screen history. Changing this will only serve to confuse users.
The first sentence in the Android Design Guidelines for Navigation with Back and Up points exactly to this point:
Consistent navigation is an essential component of the overall user experience. Few things frustrate users more than basic navigation that behaves in inconsistent and unexpected ways.
You should maintain the expected functionality of the Back button, as documented in the link above, to provide a consistent navigation pattern within your app. Doing otherwise will not benefit your users.
answered Oct 25, 2014 at 16:55
