我有 8 个标签。由于所有选项卡都应显示自定义列表，因此我正在尝试添加相同的 Fragment 实例。我正在使用 OnEventBackGroundThread 中的 EventBus 下载列表并将其添加到 OnEventMainThread 中的适配器。
我可以看到 PageSlidingTabStrip 下载所选选项卡的数据以及其他两个选项卡的数据（在所选选项卡旁边）。标签标题是准确的。我能够下载每个选项卡的数据。现在的问题是选项卡显示错误的视图。有时，下一个选项卡的数据，有时是上一个选定选项卡的数据。我经历了这个解决方案，但对我不起作用。
PagerSlidingTabStrip：如何在运行时刷新当前选项卡中的内部片段 Listview 并停止为下一个选项卡加载数据。
应该怎么做才能显示正确的视图？
我们可以将每个片段保存在destroy方法中并重复使用吗？
如果我使用 AsyncTask（而不是 EventBus）实现下载任务，选项卡将按预期工作。我是否缺少 EventBus 中的任何内容，因为我对所有这些概念都不熟悉。我是安卓新手。
我正在尝试创建类似于 youtube 应用程序的应用程序。导航抽屉中的每个项目都会有新的片段，其中包含选项卡和每个选项卡中的项目列表。
这是我的代码。
TabsFragmentPageAdapter
public class TabsFragmentPagerAdapter extends FragmentStatePagerAdapter {
private ArrayList<String> tabTitles = new ArrayList<String>(); // Contains name of the tab
private ArrayList<Integer> subCategoryIdList = new ArrayList<Integer>(); // Contains its id
private ArrayList<CategoryModel> categoryModelArrayList = new ArrayList<CategoryModel>();
private int categoryId;
public TabsFragmentPagerAdapter(FragmentManager fm, int cid) {
super(fm);
this.categoryId = cid;
categoryModelArrayList = TabsFragment.subCategoriesHashMap.get(cid); // Gets prepopulated data from other class.
for(CategoryModel c: categoryModelArrayList) {
tabTitles.add(c.getName());
subCategoryIdList.add(c.getCategoryId());
}
}
@Override
public int getCount() {
return tabTitles.size();
}
@Override
public Fragment getItem(int position) {
return AllCategoriesFragment.getInstance(subCategoryIdList.get(position));
// Using same Fragment. Position is used as a parameter(Using Id's instead of position which is populated in Constructor)
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles.get(position);
}
@Override
public void destroyItem(ViewGroup container,int position, Object object ) {
Log.d("Destroy","Destroying tab# "+position);
FragmentManager manager = ((Fragment) object).getFragmentManager();
FragmentTransaction trans = manager.beginTransaction();
trans.remove((Fragment) object);
trans.commit();
super.destroyItem(container, position, object);
container.removeView(container.getRootView());
}
}
AllCategoriesFragment.java
package com.android.thetake;
// import statements
public class AllCategoriesFragment extends Fragment implements AbsListView.OnItemClickListener, AbsListView.OnScrollListener {
private View view;
private OnFragmentInteractionListener mListener;
/**
* The fragment's ListView/GridView.
*/
private AbsListView mListView;
/**
* The Adapter which will be used to populate the ListView/GridView with
* Views.
*/
private ListAdapter mAdapter;
private CustomListAdapter customListAdapter;
MessageListEvent msgEvent = new MessageListEvent();
private static int categoryId=0;
private static int startIndex=1;
private Activity mActivity;
static List<Item> newItemList= new LinkedList<Item>();
static AllCategoriesFragment allCategoriesFragment;
static EventBus eventBus;
public static final String CATEGORY_ID = "CATEGORY_ID";
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public AllCategoriesFragment() {
startIndex = 1;
newItemList.clear();
}
public static AllCategoriesFragment getInstance(int categoryId) {
Bundle args = new Bundle();
args.putInt(CATEGORY_ID,categoryId);
allCategoriesFragment = new AllCategoriesFragment();
allCategoriesFragment.msgEvent.itemList.clear();
allCategoriesFragment.newItemList.clear();
startIndex=1;
allCategoriesFragment.setArguments(args);
return allCategoriesFragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
customListAdapter = null;
view = inflater.inflate(R.layout.fragment_item, container, false);
allCategoriesFragment.categoryId = getArguments().getInt(CATEGORY_ID);
eventBus = EventBus.getDefault();
if (!eventBus.isRegistered(this))
eventBus.register(this); //Register this class to eventBus
eventBus.post(new StartDownloadEvent()); // publish event
return view;
}
public void onEventBackgroundThread(StartDownloadEvent event) {
//Downloading the images in background thread
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
String url = "https://company.com/listProducts?categoryId="+allCategoriesFragment.categoryId+"&start="+AllCategoriesFragment.startIndex+"&limit=20";
HttpGet httpGet = new HttpGet(url);
String results = null;
boolean flag = msgEvent.itemList.size()==0;
try {
HttpResponse response = httpClient.execute(httpGet, localContext);
HttpEntity entity = response.getEntity();
results = msgEvent.getASCIIContentFromEntity(entity);
if (results != null) {
JSONArray jsonArray = new JSONArray(results);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject obj = jsonArray.getJSONObject(i);
String product_id = obj.getString("product_id");
String actorImageLink = obj.getString("500pxCropLink");
String actorName=new String();
try {
actorName = obj.getString("actorName");
} catch (JSONException e) {
Log.d("Exception",e.getLocalizedMessage());
}
String largePicLink = obj.getString("500pxCropLink");
String smallPicLink = obj.getString("125pxLink");
String movieName = obj.getString("movieName");
String itemName = obj.getString("name");
String brand = obj.getString("brand");
String price = obj.getString("price");
boolean isMatchVerified = obj.getBoolean("verified");
Item item = new Item(product_id, actorImageLink, largePicLink, smallPicLink, movieName, itemName, brand, actorName, price, isMatchVerified);
if(flag) {
msgEvent.itemList.add(item);
} else
newItemList.add(item);
}
}
} catch(IOException e) {
Log.d("Exception",e.getLocalizedMessage());
}
catch (JSONException e) {
Log.d("Exception",e.getLocalizedMessage());
}
if(!flag) {
FragmentActivity f = getActivity();
f.runOnUiThread(new Runnable() {
@Override
public void run() {
customListAdapter.addAll(newItemList);
customListAdapter.notifyDataSetChanged();
}
});
}
EventBus.getDefault().post(msgEvent);
}
public void onEventMainThread(MessageListEvent event) {
//Create Adapter
//Set Adapter to List View
customListAdapter = new CustomListAdapter(getActivity(),event.itemList);
mListView = (ListView) view.findViewById(android.R.id.list);
mListView.setAdapter(customListAdapter);
mListView.setOnItemClickListener(this);
// This loads the next images when scrolled all the way down to bottom.
// Overrides onScroll and onScrollStateChanged function
mListView.setOnScrollListener(this);
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
int loaded = firstVisibleItem+visibleItemCount;
if(loaded>=totalItemCount && startIndex+19==loaded) {
startIndex = loaded+1;
newItemList.clear();
Log.d("Scroll","Next Start Index "+startIndex);
eventBus.post(new StartDownloadEvent());
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mActivity = activity;
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
EventBus.getDefault().unregister(this);
mListener = null;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mListener.onFragmentInteraction(msgEvent.itemList.get(position).movieName);
}
}
/**
* The default content for this Fragment has a TextView that is shown when
* the list is empty. If you would like to change the text, call this method
* to supply the text it should use.
*/
public void setEmptyText(CharSequence emptyText) {
View emptyView = mListView.getEmptyView();
if (emptyText instanceof TextView) {
((TextView) emptyView).setText(emptyText);
}
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(String id);
}
public static class StartDownloadEvent {
}
public class MessageListEvent {
public List<Item> itemList = new ArrayList<Item>();
protected String getASCIIContentFromEntity(HttpEntity entity) throws IllegalStateException, IOException {
...
return out.toString();
}
}
}