Android Studio How can I reference a activity itself inside of a Static method

Question

I'm using a "createUserWithEmailAndPassword" method from Firebase and I need to send a context (activity) to it.

But this is inside a Static method (have to be this way because I'm using Fragments.). So, I collect all the data inside the Fragment and send to "registerUser" method in the MainActivity.

So, because this methos (registerUser) is a Static Mode, the MainActivity is not being referenced by the "createUser..." from Firebase.

I've tried to use "This" keyword. I've tried to use "new" keyword, like:

MainActivity main = new MainActivity();

But both does not work and using the "new" keyword, the code is not even compiled.

Someone to help me?

The image below shows the code inside the MainActivity.

i don't think the `static` method keyword is needed here since your `MainActivity` will always be instantiated on startup. — user3170251, Jan 10 '20 at 15:47

score 1 · Answer 1 · answered Jan 10 '20 at 15:55

Static methods, by definition, don't run in the context of an enclosing class instance. There is no this instance to reference. If you need to reference another class instance from a static method, you will need to pass it as a parameter to the function.

public static String cadUsario(MainActivity activity, Usario pUsario) {
    // now use activity where needed
}

Consider also not using a static method at all. That might not be appropriate here.

TeachMeJava · Answer 2 · 2020-01-10T16:12:47.203

You can pass context object of your Activity to another Activity with constructor parameters. Check this answer Link

Your problem; If you want to use context object in same class with static context, you can create a global variable like this;

     public class MainActivity extends AppCompatActivity {

        private static Context context;

        @Override
            protected void onCreate(@Nullable Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                context = this;

            }

        public static String cadUsusario(Usuario pUsuario){

        // use "context" variable by itself or create new variable. It's up to you.
        Context myContext = context;
        // your codes below

        }
}

score 1 · Accepted Answer · answered Jan 10 '20 at 17:19

I'm really so glad to your answers and they are very enlightening to me.

A brazilian friend help me in this task:

He taught me to write this code inside the Fragment, using getActivity in onAttach from Fragment and declare a private Context context. So, I could use getActivity with Firebase.

Android Studio How can I reference a activity itself inside of a Static method

3 Answers3