How to fix this error with Android and Firebase

Question

I try to write code to switch activity from MainActivity to SecondActivity . And in SecondActivity , I initialize a FirebaseFirestore object in onCreate() method. I use a button in activity_main.xml to switch from MainActivity to SecondActivity . However, my app crashes. It did not go to the SecondActivity after I clicked the button. I really need help to solve this problem. And I need to write some data to firebase through FirebaseFirestore object in Secondctivity .

I think the main reason for this crash is I initialized FirebaseFirestore object in onCreate() method. Once I commented out this initialization, crash disappeared.

public class SecondActivity extends AppCompatActivity {

    EditText name;
    EditText age;
    private static final String TAG = "SecondActivity";
    FirebaseFirestore db;
    Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second2);
        name = findViewById(R.id.name);
        age = findViewById(R.id.age);
        button = findViewById(R.id.button2);
        Toast.makeText(this, "testing", Toast.LENGTH_SHORT).show();
        db = FirebaseFirestore.getInstance();
    }
}

The errors are the following.

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.hw1, PID: 25341 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hw1/com.example.hw1.SecondActivity}: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.example.hw1. Make sure to call FirebaseApp.initializeApp(Context) first.

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)

at android.app.ActivityThread.-wrap11(Unknown Source:0)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)

at android.os.Handler.dispatchMessage(Handler.java:105)

at android.os.Looper.loop(Looper.java:164)

at android.app.ActivityThread.main(ActivityThread.java:6541)

at java.lang.reflect.Method.invoke(Native Method)

at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Caused by: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.example.hw1. Make sure to call FirebaseApp.initializeApp(Context) first.

at com.google.firebase.FirebaseApp.getInstance(com.google.firebase:firebase-common@@16.1.0:245)

at com.google.firebase.firestore.FirebaseFirestore.getInstance(com.google.firebase:firebase-firestore@@18.2.0:70)

at com.example.hw1.SecondActivity.onCreate(SecondActivity.java:37)

at android.app.Activity.performCreate(Activity.java:6975)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)

at android.app.ActivityThread.-wrap11(Unknown Source:0)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)

at android.os.Handler.dispatchMessage(Handler.java:105)

at android.os.Looper.loop(Looper.java:164)

at android.app.ActivityThread.main(ActivityThread.java:6541)

at java.lang.reflect.Method.invoke(Native Method)

at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

I/zygote: Do partial code cache collection, code=16KB, data=20KB

After code cache collection, code=16KB, data=20KB

I/zygote: Increasing code cache capacity to 128KB I/zygote: Do partial code cache collection, code=16KB, data=37KB

After code cache collection, code=16KB, data=37KB

Increasing code cache capacity to 256KB

I/zygote: JIT allocated 71KB for compiled code of void android.widget.TextView.(android.content.Context, android.util.AttributeSet, int, int)

Compiler allocated 4MB to compile void android.widget.TextView.(android.content.Context, android.util.AttributeSet, int, int)

Answer 1

You need call

FirebaseApp.initializeApp(Context);

before

db = FirebaseFirestore.getInstance();

Answer 2

See this explanation of FirebaseApp , I don't think it's needed to call initializeApp in your code like the error log suggested, unless you're using a different Firebase project. I think the problem is either in your program's initialize process, or you have a wrong configuration for your project, for example, a wrong/corrupted google-services.json file, a wrong package name set up in the Firebase console, or other things that are likely to cause a problem.