1
我有2个片段（片段A和片段B），带有使用.json加载数据的函数。如果数据已经加载，停止从.json加载数据
当我点击片段A时，数据会加载，当我点击片段B时，数据也会加载。
当我再次单击片段A时，数据将被重新加载并复制（附加第一次单击的数据）。
如何在数据已经加载时停止加载数据？
例如图像
这里我的片段代码
fragment_a.java
public class fragment_a extends Fragment {
// Log tag
private static final String TAG = MovieFragment1.class.getSimpleName();
// Movies json url
private static final String url = "http://.......";
private ProgressDialog pDialog;
private List<Movie> movieList = new ArrayList<Movie>();
private ListView listView;
private CustomListAdapter adapter;
public MovieFragment1() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onDestroy() {
super.onDestroy();
hidePDialog();
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_list, container, false);
// Inflate the layout for this fragment
final ListView listView = (ListView) rootView.findViewById(R.id.list);
adapter = new CustomListAdapter(getActivity(), movieList);
listView.setAdapter(adapter);
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);
Movie movie = new Movie();
if (obj.getString("tipe").equals("chest")){
movie.setTitle(obj.getString("name"));
movie.setThumbnailUrl(obj.getString("images1"));
//movie.setDescribe(obj.getString("describe"));
//movie.setRating(((Number) obj.get("rating"))
// .doubleValue());
movie.setYear(obj.getInt("id"));
movie.setTipe(obj.getString("tipe"));
/*// Genre is json array
JSONArray genreArry = obj.getJSONArray("genre");
ArrayList<String> genre = new ArrayList<String>();
for (int j = 0; j < genreArry.length(); j++) {
genre.add((String) genreArry.get(j));
}
movie.setGenre(genre);*/
// 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);
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
@Override
public void onDetach() {
super.onDetach();
}
}
fragment_b.java
public class fragment_b extends Fragment {
// Log tag
private static final String TAG = MovieFragment1.class.getSimpleName();
// Movies json url
private static final String url = "http://......";
private ProgressDialog pDialog;
private List<Movie> movieList = new ArrayList<Movie>();
private ListView listView;
private CustomListAdapter adapter;
public MovieFragment1() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onDestroy() {
super.onDestroy();
hidePDialog();
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_list, container, false);
// Inflate the layout for this fragment
final ListView listView = (ListView) rootView.findViewById(R.id.list);
adapter = new CustomListAdapter(getActivity(), movieList);
listView.setAdapter(adapter);
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);
Movie movie = new Movie();
if (obj.getString("tipe").equals("forearm")){
movie.setTitle(obj.getString("name"));
movie.setThumbnailUrl(obj.getString("images1"));
//movie.setDescribe(obj.getString("describe"));
//movie.setRating(((Number) obj.get("rating"))
// .doubleValue());
movie.setYear(obj.getInt("id"));
movie.setTipe(obj.getString("tipe"));
/*// Genre is json array
JSONArray genreArry = obj.getJSONArray("genre");
ArrayList<String> genre = new ArrayList<String>();
for (int j = 0; j < genreArry.length(); j++) {
genre.add((String) genreArry.get(j));
}
movie.setGenre(genre);*/
// 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);
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
@Override
public void onDetach() {
super.onDetach();
}
}
tabfragment.java（片段适配器）
public class TabFragment extends Fragment {
public static TabLayout tabLayout;
public static ViewPager viewPager;
public static int int_items = 3 ;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
/**
*Inflate tab_layout and setup Views.
*/
View x = inflater.inflate(R.layout.tab_layout,null);
tabLayout = (TabLayout) x.findViewById(R.id.tabs);
viewPager = (ViewPager) x.findViewById(R.id.viewpager);
/**
*Set an Apater for the View Pager
*/
viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));
/**
* Now , this is a workaround ,
* The setupWithViewPager dose't works without the runnable .
* Maybe a Support Library Bug .
*/
tabLayout.post(new Runnable() {
@Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
}
});
return x;
}
class MyAdapter extends FragmentPagerAdapter{
public MyAdapter(FragmentManager fm) {
super(fm);
}
/**
* Return fragment with respect to Position .
*/
@Override
public Fragment getItem(int position)
{
switch (position){
case 0 : return new fragment_a();
case 1 : return new HomeFragment();
case 2 : return new fragment_b();
}
return null;
}
@Override
public int getCount() {
return int_items;
}
/**
* This method returns the title of the tab according to the position.
*/
@Override
public CharSequence getPageTitle(int position) {
switch (position){
case 0 :
return "Chest";
case 1 :
return "Movie";
case 2 :
return "Forearm";
}
return null;
}
}
}
您正在存储数据的位置。在活动级别或片段级别。如果您在活动级别存储，那么简单的空检查就足够了。 – nilkash
@nilkash在moviefragment.javathen的片段中存储数据，你能举个例子吗？ –
清除您的fragment_b的fragment_b里面onResponse –