android - "R cannot be resolved to a variable" error goes away after building project -

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i getting "r cannot resolved variable" error of sudden. read thread on issue , says update android build tools make error go away did not fix it. reason error goes away when build project.

what going on here?

i found happening me broken layout. no need worry. trying best giving solution:

solution:

  • make sure r. links not broken. fix errors in xml files. if in adks broken, r not regenerate.

  • if somehow hit , created import android.r in activity, remove it.

  • run project -> clean. delete , regenerate r , buildconfig.

  • make sure project -> build automatically ticked. if not, build manually via menu -> project -> build project .

wait few seconds errors disappear.

if doesn't work:

  • delete inside /gen/ folder

if still doesn't work:

  • try right-clicking project -> android tools -> fix project properties.

check *.properties files (in root folder of app folder) , make sure links in there not broken.

right-click project > properties > android.

look @ project build target , library sections on right side of page. build target should match target in androidmanifest.xml. if it's set target 17 in androidmanifest, make sure target name android 4.2. if library has x under reference, remove , re-add library until there's green tick. might happen if you've moved few files , folders around.

what if r doesn't regenerate

  • this happens when have broken xml file.

  • check errors inside xml files, within /res/ folder

  • common places /layout/ , /values/ if you've changed 1 of them recently

  • check androidmanifest.xml, find change string, , forget change string name androidmanifest.xml.

  • check android sdk build-tools installed. window->android sdk manager->tools->android sdk build-tools

  • make sure when update android sdk tools, update android sdk platform-tools , android ask build-tools. build fails silently if don't match.

if can't find issue:

  • right click /gen/ -> restore local history... -> tick r.java -> click restore. doesn't solve problem, clear out errors make problem easier find.

hope you. :)


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