I've create key for android application , and set the debug sha1 from key store debug which android studio should use.
I extract the sha1 using this command :
keytool -list -v -keystore debug.keystore -alias androiddebugkey -storepass android -keypass android
I double check that I set correctly the key and the package name at the google developer. and also delete the key and generate another one, but that doesn't help, google maps deosn't appear.
please notice that my production app work perfect.
What may be the problem ?
EDIT: logcat show this:
Failed to load map. Error contacting Google servers. This is probably an authentication issue (but could be due to network errors).
SOLVED: I forget to enable the map api at the google project console, the log cat doesn't doesn't show this problem.