// Read from the database

    mFirebaseDatabase.getReference("airvisual-e9c40").orderByChild("Time").equalTo(time).addListenerForSingleValueEvent(
            new ValueEventListener() {

                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    for (DataSnapshot data : dataSnapshot.getChildren()) {
                        // here the user will have the specified email only
                        Toast.makeText(getApplicationContext(), "Done", Toast.LENGTH_LONG).show();
                    }

                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {

                }

            });
}