android - What is the use of a ...-v21.xml? -


i developing app android version 4.0 , up. updated appcompat 22.2.0 seeing these references ...-v21 / v22.xml's on web. used for? make difference? in advance!

i had themes.xml in values-v21 folder

a res/values-v21/ directory contains resources used when device running app on api level 21 or higher. if device running on older version of android, res/values-v21/ directory ignored.

what used for? make difference?

they used provide different versions of resources different versions of android.

in case of themes.xml file, api level 21+ device have theme inherits theme.material. however, theme not exist on older devices. if have theme in res/values/ tries refer theme.material, app crash on older devices. so, instead, put theme in res/values/ work on devices supporting (e.g., theme.holo minsdkversion of 11 or higher), , override theme in res/values-v21/ instead use theme.material.

you can see in this sample app, theme.apptheme (my app's theme) inherits theme.holo in res/values/ , inherits theme.material in res/values-v21/. version of theme.apptheme used @ runtime depends on version of android device has.


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