无法在Adapter Class的getView（）方法中获取arrayList的值

Question

这是我的getView（）方法，我试图在从凌空中取出后设置距离值。这里距离计算是正确的。

public View getView(final int position, View convertView, ViewGroup parent)

   {
        listrowposition = position;

        if (convertView == null)
        {
            LayoutInflater inflater = getActivity().getLayoutInflater();
            convertView = inflater.inflate(R.layout.singlerowallassigendloction, null);

            holder = new ViewHolder();

            holder.distance = (TextView) convertView.findViewById(R.id.distance);
                            holder.lati = (TextView) convertView.findViewById(R.id.lati);
            holder.longi = (TextView) convertView.findViewById(R.id.longi);

            convertView.setTag(holder);
        }
        else
        {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.lati.setText(salesmanlocationArrayList.get(listrowposition).getLati());
        holder.longi.setText(salesmanlocationArrayList.get(listrowposition).getLongi());

               double lat1= Double.parseDouble(holder.lati.getText().toString());
        double lng1= Double.parseDouble(holder.longi.getText().toString());

        vollyRequest_Fetch_distance(lat1,lng1,lat,lng);

        Log.d("distance_ll=","tex="+text+"   "+value+" "+lat1);

        double d= Double.parseDouble(value)/1000;
        holder.distance.setText(""+new DecimalFormat("##.##").format(d)+" KM");
        return convertView;
    }

这是我的截击请求代码

public void vollyRequest_Fetch_distance(double lat11, double lon11, double lat22, double lon22)
{
    String url = "https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins="+lat11+","+lon11+"&"+"destinations="+lat22+","+lon22;

    Log.d("RESPOetchlocation..>>> ", url + "<<<");

    RequestQueue queue = Volley.newRequestQueue(getActivity());

    StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String>()
    {
        @Override
        public void onResponse(String response)
        {
            Log.d("RESPONFetchlocation>>> ", response + "<<<");
            // progressDialog.dismiss();
            Jsonresponse_Distance(response);

        }
    },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("RESPONSE:Error>>> ", error.toString() + "<<<");
                    // progressDialog.dismiss();
                }
            }) {
        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<String, String>();

            return params;
        }

        @Override
        public Map<String, String> getHeaders() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("key", "Arz5SyA5UFy-pTsr5cIdwxghhnV6BoH-pCJBARg");
            return params;
        }
    };
    queue.add(request);

}

public void Jsonresponse_Distance(String str)
{
    JSONObject jsonObject = null;
    JSONArray jsonArray = null;
    JSONArray jsonArray_elements = null;
    JSONObject jsonObject_elements = null;
    JSONObject jobj;
    String error = null;
    String msg = null;
    try
    {
        jsonObject = new JSONObject(str);
        Log.d("jsonObject==", jsonObject.toString());

        msg = jsonObject.getString("status");
        if (msg.equals("OK"))
        {
                jsonArray = jsonObject.getJSONArray("rows");

                Log.d("jsonArray.length()=",""+jsonArray.length());

            for (int i = 0; i < jsonArray.length(); i++)
                {
                    jobj= jsonArray.getJSONObject(i);
                    jsonArray_elements= jobj.getJSONArray("elements");

                    Log.d("jsonArray_ets.length()=",""+jsonArray_elements.length());

                    for (int j = 0; j < jsonArray_elements.length(); j++)
                    {
                        jsonObject_elements= jsonArray_elements.getJSONObject(0);
                        Log.d("jsonObject_elements=",jsonObject_elements.toString());

                        JSONObject job=  jsonObject_elements.getJSONObject("distance");

                        Log.d("job=",job.toString());

                        text= job.getString("text");
                        value= job.getString("value");
                        Log.d("job=",""+text+" "+value);

                    }

                }

        }
        else
        {

        }

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

} 

我得到了值（距离）的正确结果，但在getview方法中获取null请帮助我。

//这里我试图在获取截击请求后设置我的适配器

public void Jsonresponse_Viewlocation(String str)
    {


JSONObject jsonObject = null;
    JSONArray jsonArray = null;
    JSONObject jobj;
    String error = null;
    String msg = null;
    salesmanlocationArrayList.clear();
    try
    {
        jsonObject = new JSONObject(str);
        Log.d("jsonObject==", jsonObject.toString());
        msg = jsonObject.getString("status");
        if (msg.equals("true")) {
            jsonArray = jsonObject.getJSONArray("response");
            for (int i = 0; i < jsonArray.length(); i++)
            {
                salesmanlocation = new Salesmanlocation();
                jobj = jsonArray.getJSONObject(i);

                address = jobj.getString("address");
                salesmanlocation.setAddress(address);                                                    salesmanlocation.setAddress(jobj.getString("address"));
                String latlong_string=getLocationFromAddress(address);
                String latlong[]=latlong_string.split(",");
                String lat1=latlong[0];
                String lng1=latlong[1];

                Log.d("latlng==",""+lat1+" "+lng1);
                double latt= Double.parseDouble(lat1);
                double lng1g= Double.parseDouble(lng1);

                salesmanlocation.setLati(String.valueOf(lat1));
                salesmanlocation.setLongi(String.valueOf(lng1));
                salesmanlocationArrayList.add(salesmanlocation);
            }

        }
        else
        {
        }

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

     adapter = new Baseddapter_Allassignloc();
     alllist.setAdapter(adapter);

}