我在使用选项卡/滑动时遇到了许多与片段相关的问题。我有一个活动和两个片段，其中一个有一个ListView。我想要的是，当我从片段1向右滑动到具有ListView的片段时，刷新ListView或者如果可能的话重新创建第二个片段...
我现在正在尝试使用FragmentTransaction.replace()来实现：
我现在正在尝试使用FragmentTransaction.replace()来实现：
public void onTabSelected(Tab arg0, android.app.FragmentTransaction arg1) {
// TODO Auto-generated method stub
Fragment frag = new FragmentTwo();
FragmentTransaction trans = getSupportFragmentManager().beginTransaction();
if (arg0.getPosition() == 1) {
trans.replace(R.id.pager, frag);
trans.addToBackStack(null);
trans.commit();
}
}
我认为当我滑动到带有ListView的第二个选项卡时，它会用新的选项卡替换它创建的旧选项卡。但实际上发生的是，当我划到第二个选项卡时，它会重新创建带有ListView的片段（我知道这一点，因为在onCreateView中有一个对话框显示在屏幕上），但是然后该片段/选项卡变成了空白/黑色。我做错了什么？这个被创建的片段去哪里了？
我不知道片段的代码是否相关，但如果需要请告诉我，我可以贴出来。这是我的PagerAdapter类。
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new FragmentOne();
case 1:
return new FragmentTwo();
case 2:
return new FragmentThree();
}
return null;
}
@Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
}
感谢任何帮助！我真的为这个问题苦恼 :(
编辑：
当您从选项卡1滑动到选项卡2时，选项卡2会显示我的对话框，然后加载该选项卡，但如果我回到选项卡1，它就全部变黑...然后如果我再次转到选项卡2，它会再次创建并显示我的对话框，然后再次变黑...
编辑：（添加listview片段代码）
public class FragmentTwo extends Fragment {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser_Helpers2 jParser = new JSONParser_Helpers2();
ArrayList<HashMap<String, String>> tripList;
// url to get all products list
private static String url_all_trips = "http://10.0.2.2/android_connect/get_all_trips.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_TRIPS = "trips";
private static final String TAG_TRIPID = "tripid";
private static final String TAG_TRIPNAME = "tripName";
private static final String TAG_UID = "uid32";
// products JSONArray
JSONArray trips = null;
View rootView;
Button btnRefresh;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
//View rootView = inflater.inflate(R.layout.fragment_one, container, false);
rootView = inflater.inflate(R.layout.fragment_two, container, false);
btnRefresh = (Button) rootView.findViewById(R.id.refresh);
// Hashmap for ListView
tripList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = (ListView) rootView.findViewById(R.id.list);
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//getting values from selected ListItem
String tripid = ((TextView) view.findViewById(R.id.pid)).getText().toString();
//starting new intent
Intent in = new Intent(getActivity(), EditTrip_Activity.class);
//sending pid to next activity
in.putExtra(TAG_TRIPID, tripid);
//starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
return rootView;
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
ListView lv = (ListView) rootView.findViewById(R.id.list);
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Loading your trips. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_trips, "GET", params);
// Check your log cat for JSON response
Log.d("All Trips: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
trips = json.getJSONArray(TAG_TRIPS);
// looping through All Products
for (int i = 0; i < trips.length(); i++) {
JSONObject c = trips.getJSONObject(i);
// Storing each json item in variable
String tripid = c.getString(TAG_TRIPID);
String tripname = c.getString(TAG_TRIPNAME);
String userId = c.getString("uid");
// creating new HashMap
DatabaseHandler_Helpers db = new DatabaseHandler_Helpers(getActivity());
HashMap<String, String> map = new HashMap<String, String>();
if (userId.equals(db.getUserDetails().get("uid"))) {
// adding each child node to HashMap key => value
map.put(TAG_TRIPID, tripid);
map.put(TAG_TRIPNAME, tripname);
// adding HashList to ArrayList
tripList.add(map);
} //else {
//map.put(TAG_TRIPID, "");
//map.put(TAG_TRIPNAME, "You have no tracked trips.");
//tripList.add(map);
//}
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getActivity(),
NewTrip_Activity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
((Activity) getActivity()).runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
getActivity(), tripList,
R.layout.list_item, new String[] { TAG_TRIPID,
TAG_TRIPNAME},
new int[] { R.id.pid, R.id.name });
// updating listview
((ListView) lv.findViewById(R.id.list)).setAdapter(adapter);
}
});
}
}
}