How to get a String List from Firebase to fill a S

问题:

my database is arranged like this:

I want to get all the values from areaName as a String List or any form of list and use it to populate a Spinner. The problem I am getting is that it only retrieves the last value (in this case "New York"). This is my actual code:

fDatabaseRoot.child("areas").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot areaSnapshot: dataSnapshot.getChildren()) {
                String areaName = areaSnapshot.child("areaName").getValue(String.class);

                Spinner areaSpinner = (Spinner) findViewById(R.id.spinner);
                final String[] areas = {areaName};
                ArrayAdapter<String> areasAdapter = new ArrayAdapter<String>(UAdminActivity.this, android.R.layout.simple_spinner_item, areas);
                areasAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                areaSpinner.setAdapter(areasAdapter);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

回答1:

I don't test that code but, more or less, that is what you have to do:

fDatabaseRoot.child("areas").addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        // Is better to use a List, because you don't know the size 
        // of the iterator returned by dataSnapshot.getChildren() to
        // initialize the array
        final List<String> areas = new ArrayList<String>();

        for (DataSnapshot areaSnapshot: dataSnapshot.getChildren()) {
            String areaName = areaSnapshot.child("areaName").getValue(String.class);
            areas.add(areaName);
        }

        Spinner areaSpinner = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter<String> areasAdapter = new ArrayAdapter<String>(UAdminActivity.this, android.R.layout.simple_spinner_item, areas);
        areasAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        areaSpinner.setAdapter(areasAdapter);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});

I hope it's helps!

Regards.