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（选定选项卡旁边）。标签标题是准确的。我可以下载每个标签的数据。
现在的问题是标签显示错误的视图。有时，下一个选项卡的数据，有时是前一个选定选项卡的数据。
我经历了这个解决方案，但没有为我工作。
PagerSlidingTabStrip: How refresh inner fragment Listview in current tab at run time and stop the loading data for next tab
如何显示正确的视图？
我们可以在destroy方法中保存每个片段并重复使用吗？
如果我使用AsyncTask（而不是EventBus）实现下载任务，则标签按预期工作。我在EventBus中遗漏了什么，因为我是所有这些概念的新手。 我是Android的新手。
我正在尝试创建类似于youtube应用的应用。导航抽屉中的每个项目都将包含带有选项卡的新片段以及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();
}
}
}
答案 0 :(得分：0)
在观察选项卡的行为后，这应该适合您。
@Override
public Fragment getItem(int position) {
if(position==0){
return AllCategoriesFragment.getInstance(subCategoryIdList.get(position));
}else{
int index=position-1;
return AllCategoriesFragment.getInstance(subCategoryIdList.get(index));
}
}
答案 1 :(得分：0)
PageSlidingTabStrip显然是错误的，以避免我建议的并发症Android PagerSlidingTabStrip (default Material Design)
实施非常相似。但是，这也会为您提供更好的自定义选项