Android Engineering Error Resolution unable to resolve target ' android-17 '

Transferred from: http://www.cnblogs.com/csulennon/p/3705177.html

After swapping the system, reinstall the Android SDK and ADT plugin to import the previous workspace. Actually found all the Android projects are error.

My previous SDK version was 17, and the upgrade was 19.

   1:  [2014-05-03 14:56:25-thinkblink] Unable to resolve target ' android-17 '

   2:  [2014-05-03 14:56:26-game2048publish] Unable to resolve target ' Google inc.:google apis:17 '

   3:  [2014-05-03 14:56:26-helloeeg] Unable to resolve target ' android-12 '

Modify the project directory:

Fix it in Eclipse.

Android Engineering Error Resolution unable to resolve target ' android-17 '