Spinner with an initial text

Cordial greeting, by means of a query to a page:

http://localhost/baradm/ubica.php?id=002

I get the answer .json:

[{"DESCRP":"MESA 01"},{"DESCRP":"CUARTO 01"},{"DESCRP":"CUARTO 02"}]

This I have uploaded to a Spinner:

And I wish that the text LOCATION ... appears to me as an initial text and that this is not selectable, I have placed a help in this link , but I do not know how to implement it, I enclose the java classes with which I fill the spinner.

Thanks in advance.

PEDIDOFRAGMENT.JAVA

package com.windroid.dinas;

import...;


public class PedidoFragment extends Fragment{

    final static String urlAddress="http://10.0.3.2/baradm/ubica.php?id=";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_pedido, container, false);
        final Spinner spinnerUbica = (Spinner) view.findViewById(R.id.spUbica);

        new Downloader(getActivity(),urlAddress+GlobalVariables.getUsr(),spinnerUbica).execute();

        return view;
    }

}

DOWNLOADER.JAVA

package com.windroid.dinas;

import...

public class Downloader extends AsyncTask<Void,Void,String> {

    Context c;
    String urlAddress;
    Spinner sp;

    ProgressDialog pd;


    public Downloader(Context c, String urlAddress, Spinner sp) {
        this.c = c;
        this.urlAddress = urlAddress;
        this.sp = sp;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd=new ProgressDialog(c);
        pd.setTitle("Buscando");
        pd.setMessage("Buscando...Por favor, espere");
        pd.show();
    }

    @Override
    protected String doInBackground(Void... params) {
        return this.downloadData();
    }


    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

        pd.dismiss();

        if(s==null)
        {
            Toast.makeText(c,"No se puede recuperar, valor nulo devuelto",Toast.LENGTH_SHORT).show();
        }else
        {
            Toast.makeText(c,"Exito",Toast.LENGTH_SHORT).show();

            //CALL PARSER CLASS TO PARSE
             DataParser parser=new DataParser(c,sp,s);
            parser.execute();
        }
    }

    private String downloadData()
    {
        HttpURLConnection con=Connector.connect(urlAddress);
        if(con==null)
        {
            return null;
        }

        InputStream is=null;
        try {

            is=new BufferedInputStream(con.getInputStream());
            BufferedReader br=new BufferedReader(new InputStreamReader(is));

            String line=null;
            StringBuffer response=new StringBuffer();

            if(br != null)
            {
                while ((line=br.readLine()) != null)
                {
                    response.append(line+"\n");
                }

                br.close();

            }else {
                return null;
            }

            return response.toString();

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(is != null)
            {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }
}

DATAPARSER.JAVA

package com.windroid.dinas;

import...


public class DataParser extends AsyncTask<Void,Void,Integer> {

    Context c;
    Spinner sp;
    String jsonData;

    ProgressDialog pd;
    ArrayList<String> spacecrafts=new ArrayList<>();

    public DataParser(Context c, Spinner sp, String jsonData) {
        this.c = c;
        this.sp = sp;
        this.jsonData = jsonData;
    }


    @Override
    protected void onPreExecute() {
        super.onPreExecute();


        pd=new ProgressDialog(c);
        pd.setTitle("Buscando");
        pd.setMessage("Buscando...Por favor, espere");
        pd.show();
    }

    @Override
    protected Integer doInBackground(Void... params) {
        return this.parseData();
    }

    @Override
    protected void onPostExecute(Integer result) {
        super.onPostExecute(result);

        pd.dismiss();

        if(result==0)
        {
            Toast.makeText(c,"No se puede analizar",Toast.LENGTH_SHORT).show();
        }else
        {
            //Toast.makeText(c,"Analizado con Exito",Toast.LENGTH_SHORT).show();

            //BIND
            ArrayAdapter adapter=new ArrayAdapter(c,android.R.layout.simple_spinner_dropdown_item,spacecrafts);

            adapter.add("UBICACION...");
            sp.setAdapter(adapter);


            sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

                    Toast.makeText(c,spacecrafts.get(position),Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {

                }
            });

        }
    }

    private int parseData()
    {
        try {
            JSONArray ja=new JSONArray(jsonData);
            JSONObject jo=null;

            spacecrafts.clear();
            Spacecraft s=null;

            for(int i=0;i<ja.length();i++)
            {
                jo=ja.getJSONObject(i);

                //int id=jo.getInt("id");
                String name=jo.getString("DESCRP");

                s=new Spacecraft();
                //s.setId(id);
                s.setName(name);

                spacecrafts.add(name);
            }

            return 1;

        } catch (JSONException e) {
            e.printStackTrace();
        }

        return 0;

    }

}

ESPACECRAFT.JAVA

package com.windroid.dinas.mDataObject;

public class Spacecraft {

    String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}