Volley does not stop adding date to listview from json

问题

I want app to show dates in listview. My app has TabLayout which imitates this and Listviews which imitate this.So, tabs have listview. After showing all json dates in listview, they load json dates again.
It happens when I swipe each tabs like tab1→tab2→tab3→tab1→tab3....
This is may code. If anyone knows what is wrong, please teach me.

public class AppController extends Application {
public static final String TAG = AppController.class.getSimpleName();
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static AppController mInstance;

@Override
public void onCreate() {
    super.onCreate();
    mInstance = this;
}
public static synchronized AppController getInstance() {
    return mInstance;
}
public RequestQueue getRequestQueue() {
    if (mRequestQueue == null) {
        mRequestQueue = Volley.newRequestQueue(getApplicationContext());
    }
    return mRequestQueue;
}
public ImageLoader getImageLoader() {
    getRequestQueue();
    if (mImageLoader == null) {
        mImageLoader = new ImageLoader(this.mRequestQueue,
                new LruBitmapCache());
    }
    return this.mImageLoader;
}

public <T> void addToRequestQueue(Request<T> req, String tag) {
    // set the default tag if tag is empty
    req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
    getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
    req.setTag(TAG);
    getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
    if (mRequestQueue != null) {
        mRequestQueue.cancelAll(tag);
    }
}
}

Tab 1 (Tab2 and Tab3 are almost same)

    public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    adapter = new CSadapter(getActivity(),movieList);
    setListAdapter(adapter);
    getListView().setScrollingCacheEnabled(false);
    pDialog = new ProgressDialog(getActivity());
    // Showing progress dialog before making http request
    pDialog.setMessage("Loading...");
    pDialog.show();
    // Creating volley request obj
    JsonArrayRequest movieReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());
                    hidePDialog();
                    // Parsing json
                    for (int i = 0; i < response.length(); i++) {
                        try {
                            JSONObject obj = response.getJSONObject(i);
                            Song movie = new Song();
                            movie.setTitle(obj.getString("title"));
                            movie.setThumbnailUrl(obj.getString("jacket"));
                            movie.setNumber(obj.getString("number"));
                            movie.setYear(obj.getString("release"));
                            // adding movie to movies array
                            movieList.add(movie);
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                    // notifying list adapter about data changes
                    // so that it renders the list view with updated data
                    adapter.notifyDataSetChanged();
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d(TAG, "Error: " + error.getMessage());
            hidePDialog();
        }
    });
    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(movieReq);
}

回答1:

In a pager the default page limit is 1 .If you go beyond that your page activity is created again.This may be the case happening here.You can increase the page limit to avoid re creation

来源：https://stackoverflow.com/questions/25589593/volley-does-not-stop-adding-date-to-listview-from-json