FirebaseAuth.getInstance() crashes with “IllegalArgumentException: Given String is empty or null”

Question

I was trying to create a login system from my app, but it crashes when I open it. I managed to locate the bug to the line

mFirebaseAuth = FirebaseAuth.getInstance();

which makes no sense to me. Here is the code:

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //Initialize Firebase Auth
    mFirebaseAuth = FirebaseAuth.getInstance();
    mFirebaseUser = mFirebaseAuth.getCurrentUser();

    if (mFirebaseUser == null) {
        // Not logged in, launch the Log In activity
        loadLogInView();
    }
}

private void loadLogInView() {
    Intent intent = new Intent(this, LogInActivity.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(intent);
}

and the crash report:

02-20 01:04:45.137 3186-3186/? E/AndroidRuntime: FATAL EXCEPTION: main
                                                 Process: com.maegner.testingfirebase, PID: 3186
                                                 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.maegner.testingfirebase/com.maegner.testingfirebase.MainActivity}: java.lang.IllegalArgumentException: Given String is empty or null
                                                     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                                                     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
                                                     at android.app.ActivityThread.-wrap12(ActivityThread.java)..............

Answer 1

This exception can be caused by a misconfigured google-services.json file. The error will occur if the api_key is missing. Verify that your google-services.json file contains this section:

  "api_key": [
    {
      "current_key": "AIzaSyDkG-g8hH7T4TV7RrN23ccnRsXp12345678" //<-- your key here
    }
  ],

If it does not, regenerate google-services.json.

Answer 2

Make sure you have used the plugin: apply plugin: 'com.google.gms.google-services'

Some conflicts can occur with libraries such as 'com.google.android.gms: play-services-maps: 16.0.0', and in this case the plug-in is often removed as a solution, and in the case I identified, this was the problem. Take a test without the play-services libraries.