Display Firebase data to a TextView Android Studio

To do it do the following

DatabaseReference ref = FirebaseDatabase.getInstance().getReference();

    ref.child("Persona").child("Valor").addValueEventListener(new ValueEventListener() {
      @Override
      public void onDataChange(DataSnapshot dataSnapshot) {
        int valor = dataSnapshot.getValue(Integer.class);
        textView.setText(String.valueOf(valor);
      }

      @Override
      public void onCancelled(DatabaseError databaseError) {
        System.out.println("Fallo la lectura: " + databaseError.getCode());
      }
    });

First we create the reference to where the value is, and then we go and look for that value, we keep it in a variable of integer type int and then we put it in TextView with setText , we use String.valueOf since is an integer and setText needs to pass a String.

Each time that value is modified, your TextView will be modified with that value in real time.

Note: remember that the Firebase rules decide who has access to the data, so if it does not work or it does not read to you, it is not the code but your rules, you can use the following ones to debug for the moment and then in production you change them by more secure rules

Only debug. If you are not going to use authentication and it does not matter who reads or writes the database, you can leave them like this

{
  "rules": {
    ".read": true,
    ".write":true
  }
}

  

Remember that addValueEventListener ... like other listeners in Firebase   they are asynchronous, this means they work in the background   asking for the data and when they have it, they just do the action that   find within onDataChange so put the setText out   of onDataChange would not put anything since you can not access that value   before being requested.