android with firebase RealTime Database

Question

how to fix this issue "savedInstance null" when using firebase realtimeDataBase

public class MainActivity extends AppCompatActivity {

    Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn =(Button)findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                FirebaseDatabase database = FirebaseDatabase.getInstance( );
              DatabaseReference myRef = database.getReference();
              myRef.child("test").push().setValue("Nikmal");
                Toast.makeText(getApplicationContext(),"succesfully", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Answer 1

Try this code, it should works if you use a DatabaseReference

 Button btn;
DatabaseReference myRef;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    myRef = FirebaseDatabase.getInstance().getReference();



    btn =(Button)findViewById(R.id.btn);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            myRef.child("test").push().setValue("Nikmal");
            Toast.makeText(getApplicationContext(),"succesfully", Toast.LENGTH_SHORT).show();
        }
    });
}