Below code I am using for Google login.I added google-services.json file in the app folder.I am using classpath \'com.google.gms:google-services:2.0.0
google-services.json
classpath \'com.google.gms:google-services:2.0.0
solved by adding SHA-1 of debug key store in firebase console for my app which is located here C:\Users\my name.android when you make key store for release change it in firebase console