How to check if a value exists in firebase database - android

Question

I am new to firebase via Android(Java) and was wondering how to check if a user already exists in a database of the following format:

    gdb-2fbgg{

      u         


        

Answer 1

Declare hander with delay as per your preference in onCreate() and call a method from here

        Handler h = new Handler();
        h.postDelayed(new Runnable() {
            @Override
            public void run() {
                ok();
            }
        },3000);

Then create this method body

public void ok(){
    Toast.makeText(this, "Count is : "+adapter.getItemCount(), Toast.LENGTH_SHORT).show();
}

Now you will get count after specfied delay

Answer 2

Use .child("Michael").exists() method or .hasChild("Michael") with SingleValueEvent within onDataChange

DatabaseReference root = FirebaseDatabase.getInstance().getReference();
DatabaseReference users = root.child("users");
users.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            if (snapshot.child("Michael").exists()) {
                // run some code
            }else{

            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });