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[英]How can I add child fragments to a fragment in Android using a BaseAdapter
[英]Using a custom BaseAdapter for ListViews - multiple fragments?
我已經設法將自定義BaseAdapter放在一起。 該適配器用於在每個列表項中顯示三個TextView。 活動中只有一個 ListView時,絕對可以完美工作。
但是,我正在使用一個包含3個片段的片段活動-其中2個片段包含一個ListView,需要使用我的自定義適配器和XML。
在加載這兩個ListView時,在加載的第一個 ListView上觸發onItemClickListener會導致以下錯誤:
11-20 18:02:15.295: E/AndroidRuntime(18563): java.lang.IllegalStateException:
The content of the adapter has changed but ListView did not receive a
notification. Make sure the content of your adapter is not modified from
a background thread, but only from the UI thread. [in ListView(2131165192,
class android.widget.ListView) with
Adapter(class com.my.project.Adapter_CustomList)]
我不希望更改適配器-每個ListView適配器都使用一個新的Adapter_CustomList(),因此我不確定為什么它們被引用為同一適配器?
適配器將getActivity()作為上下文-因為兩者都相同,這是否引起問題? 有什么辦法可以解決這個問題,還是這又是碎片的另一個缺點?
自定義適配器大致如下,我取出了一些任意代碼塊...
public class Adapter_CustomList extends BaseAdapter {
private static ArrayList<Custom> results;
private LayoutInflater mInflater;
public Adapter_CustomList(Context context, ArrayList<Custom> res) {
results = res;
mInflater = LayoutInflater.from(context);
}
public int getCount() {
return results.size();
}
public Object getItem(int position) {
return results.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.custom_row_view, null);
holder = new ViewHolder();
//Set ViewHolder vars from inflated view
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
//Sets the TextViews
return convertView;
}
static class ViewHolder {
//Contains the TextView text vars
}
}
該活動正在使用FragmentPagerAdapter(由Eclipse生成):
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
Fragment fragment;
switch (i){
case 1:
fragment = new Frag_ListOne();
break;
case 2:
fragment = new Frag_ListTwo();
break;
default:
fragment = new Frag_Temporary();
break;
}
return fragment;
}
@Override
public int getCount() {
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0: return getString(R.string.main_fragment1).toUpperCase();
case 1: return getString(R.string.main_fragment2).toUpperCase();
case 2: return getString(R.string.main_fragment3).toUpperCase();
}
return null;
}
}
片段示例,兩者幾乎相同,但具有唯一的布局文件。
public class Frag_ListOne extends Fragment {
private ListView ListView;
private Adapter_CustomList listAdapter;
private Fetcher fetcher;
public Frag_ListOne(){}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
return inflater.inflate(R.layout.frag_list_one, container, false);
}
@Override
public void onStart(){
super.onStart();
ListView = (ListView) getActivity().findViewById(R.id.frag_one_list);
ListView.setEmptyView(getActivity().findViewById(R.id.frag_one_list_spinner));
if (listAdapter != null){
setListAdapter();
} else {
//This will always be called for now....
sendRequest();
}
}
private void sendRequest(){
fetcher = new Fetcher();
fetcher.execute("http://myapiurl.com");
}
private void cancelFetch(){
if (fetcher != null &&
(fetcher.getStatus() == AsyncTask.Status.PENDING || fetcher.getStatus() == AsyncTask.Status.RUNNING)){
fetcher.cancel(true);
}
}
private void displayError(String errMsg){
//Log errMsg
}
private void createListAdapter(ArrayList<Result> res){
listAdapter = new Adapter_CustomList(getActivity(), res);
setListAdapter();
}
private void setListAdapter(){
ListView.setAdapter(listAdapter);
ListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
Result r = (Result) ListView.getItemAtPosition(position);
Intent intent = new Intent(getActivity(), ViewResultActivity.class);
intent.putExtra(F_List.INTENT_VIEW_RESULT_OBJ, r);
startActivity(intent);
}
});
}
//Extended AsyncTask, essentially
public class Fetcher extends JSONRequest{
@Override
protected void onSuccess(JSONObject req, JSONObject res){
if (req != null && res != null){
try{
JSONArray jsons = res.getJSONArray("results");
ArrayList<Result> res = new ArrayList<Result>();
if (jsons.length() > 0){
for (int i=0;i<jsons.length();i++){
JSONObject jo = jsons.getJSONObject(i);
r = new Result();
r.setLineOne(jo.getInt("line1"));
r.setLineTwo(jo.getString("line2"));
r.setLineThree(jo.getString("line3"));
res.add(r);
}
createListAdapter(res);
} else {
//Nothing found
}
} catch (JSONException e){}
} else {
//Null received
}
}
@Override
protected void onError(String errMsg){}
@Override
protected void onCancel(){}
}
}
適配器代碼看起來還不錯-我在分開的片段中運行兩個列表視圖的過程類似。 (我假設結果實際上等於offerResults)
您附加到列表視圖的方式可能有問題嗎?
確保在片段而非活動中都引用了Adapter和listViews。
檢查是否設置了適配器,然后在不調用adapter.notifyDataSetChanged()的情況下更改驅動它的列表。
可以參考Fragments和聲明適配器的方式使用更多:)
編輯:
我正在運行一個系統,在該系統中,我將使用FragmentManager而不是FragmentPagerAdapter將2個片段充氣到FrameLayouts中。
我會仔細檢查一下是否在片段分頁器適配器中正確創建和訪問了片段。 您可以通過記錄getItem()中的fragmentId來實現
另外,請謹慎對待getItem(...)的編寫方式,因為如果您繼續產生新的片段,可能會很快導致內存不足錯誤。 相反,我將研究使用片段管理器和標簽來管理新片段的創建。
另一個想法是考慮在滑動抽屜內設置列表,以便他們可以根據需要將其拉出。
編輯2:請嘗試以下更改-這樣,列表將保存在片段的內存中,並且不屬於AsyncTask的一部分,后者可能在完成時被GC。
private ArrayList<Result> resultList = new ArrayList<Result>();
private Adapter_CustomList adapter = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View v = inflater.inflate(R.layout.frag_list_one, container, false);
listView = (ListView) v.findViewById(R.id.frag_one_list);
listView.setEmptyView(v.findViewById(R.id.frag_one_list_spinner));
adapter = new Adapter_CustomList(getActivity(), resultList);
listView.setAdapter(adapter);
}
@Override
public void onStart(){
super.onStart();
}
//Extended AsyncTask, essentially
public class Fetcher extends JSONRequest{
@Override
protected void onSuccess(JSONObject req, JSONObject res){
if (req != null && res != null){
try{
JSONArray jsons = res.getJSONArray("results");
if (jsons.length() > 0){
for (int i=0;i<jsons.length();i++){
JSONObject jo = jsons.getJSONObject(i);
r = new Result();
r.setLineOne(jo.getInt("line1"));
r.setLineTwo(jo.getString("line2"));
r.setLineThree(jo.getString("line3"));
resultList.add(r);
}
adapter.notifyDataSetChanged();
} else {
//Nothing found
}
} catch (JSONException e){}
} else {
//Null received
}
}
@Override
protected void onError(String errMsg){}
@Override
protected void onCancel(){}
}
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