Android App can't write data to Firebase Realtime database

Question

I have been following a guide on how to write data to a firebase real-time database. Though I followed every instruction my app doesn't seem to work. When I click on the send button database doesn't update. I haven't received any errors so I decided to add a phew listeners but they don't work too (none of the toasts is shown). Firebase tool says that all of the dependencies are set up correctly. Firebase project is launched in test mode so the problem can't be connected with the rules. What am i doing wrong? This how my activity code looks like:

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCanceledListener;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class MainActivity extends AppCompatActivity {
    private EditText email,name,password;
    Button btn;
    private DatabaseReference ref;
    private String USER_KEY="User";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
        initListener();
    }
    public void init(){
        email=findViewById(R.id.editTextTextPersonName);
        name=findViewById(R.id.editTextTextPersonName2);
        password=findViewById(R.id.editTextTextPersonName3);
        ref = FirebaseDatabase.getInstance().getReference().child(USER_KEY);
        btn =findViewById(R.id.button);
    }
    public void initListener(){
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String id =ref.getKey();
                String ema=email.getText().toString();
                String nam=name.getText().toString();
                String p=password.getText().toString();
                User user = new User(id,ema,nam,p);
                DatabaseReference usersRef = ref.child("users");
                usersRef.push().setValue(user).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(MainActivity.this,"Failed",Toast.LENGTH_SHORT).show();
                        System.out.println("Failed");
                    }
                }).addOnCanceledListener(new OnCanceledListener() {
                    @Override
                    public void onCanceled() {
                        Toast.makeText(MainActivity.this,"Canceled",Toast.LENGTH_SHORT).show();
                        System.out.println("Canceled");
                    }
                }).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        Toast.makeText(MainActivity.this,"Succeed",Toast.LENGTH_SHORT).show();
                        System.out.println("Succeed");
                    }
                }).addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        Toast.makeText(MainActivity.this,"Complete",Toast.LENGTH_SHORT).show();
                        System.out.println("Complete");
                    }
                });
                Toast.makeText(MainActivity.this,"end",Toast.LENGTH_SHORT).show();

            }

        });
    }

}

User class:

public class User {
    public String email,password,nickName;

    public User(String email, String password, String nickName) {
        this.email = email;
        this.password = password;
        this.nickName = nickName;
    }

    public User() {
    }
}

Gradle built file:

  plugins {
    id 'com.android.application'
    id 'com.google.gms.google-services'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 18
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.firebase:firebase-database:20.0.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}

Also, this is my first time here so don't be rude pls.

Answer 1

Just needed to reimport google-services.json file

Answer 2

u can insert your project sha1 key in firebase project setting than download the google json file and save in your app folder in android studio.