源代码
public class VendingFragment extends ListFragment {
private String Tag = "VendingFragment";
private static final String TAG_SUCCESS = "success";
private ListView listView;
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jsonParser = new JSONParser();
JSONArray vendingmachine = null;
ArrayList<HashMap<String, String>> vendinglist;
// url to get all products list
MainActivity main = new MainActivity();
private String url_all_vendingmachine = main.getIP()
+ "vendingmachine/get_all_vendingmachine.php";
// products JSONArray
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.vending_main, container, false);
vendinglist = new ArrayList<HashMap<String, String>>();
//listView = (ListView) view.findViewById(R.id.allVendingListView);
listView = getListView();
new get_all_vendingmachine().execute();
return view;
}
class get_all_vendingmachine extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Creating Product..");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
Log.i(Tag, "pDialog");
}
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
Log.i(Tag, url_all_vendingmachine);
// getting JSON Object
// Note that create product url accepts POST method
JSONObject json = jsonParser.makeHttpRequest(
url_all_vendingmachine, "GET", params);
// check log cat for response
Log.i(Tag, json.toString());
// check for success tag
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// Ada record Data (SUCCESS = 1)
// Getting Array of vendingmachine
vendingmachine = json.getJSONArray("vendings");
// looping through All vendingmachine
for (int i = 0; i < vendingmachine.length(); i++) {
JSONObject c = vendingmachine.getJSONObject(i);
// Storing each json item in variable
String id = c.getString("VMid");
String name = c.getString("Name");
String address = c.getString("Address");
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put("VMid", id);
map.put("Name", name);
map.put("Address", address);
// adding HashList to ArrayList
vendinglist.add(map);
}
} else {
// failed to create product
getActivity().finish();
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once done
pDialog.dismiss();
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
// updating listview
String[] from = { "name", "address", "id" }; int[] to = { R.id.vending_name, R.id.vending_address,
R.id.vending_id };
SimpleAdapter adapter = new SimpleAdapter(getActivity(),
vendinglist, R.layout.vending_list, from, to);
listView.setAdapter(adapter);
}
});
}
}
}
我运行，并在应用程序启动后在logcat中发现错误，logcat中没有显示log.i
错误消息：
03-15 18:21:48.680: W/dalvikvm(13868): threadid=1: thread exiting with uncaught exception (group=0x40cf12d0)
03-15 18:21:48.710: E/AndroidRuntime(13868): FATAL EXCEPTION: main
03-15 18:21:48.710: E/AndroidRuntime(13868): java.lang.IllegalStateException: Content view not yet created
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.ListFragment.ensureList(ListFragment.java:386)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.ListFragment.getListView(ListFragment.java:280)
03-15 18:21:48.710: E/AndroidRuntime(13868): at com.ecnu.vendingmachine.VendingFragment.onCreateView(VendingFragment.java:54)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:828)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1032)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.BackStackRecord.run(BackStackRecord.java:622)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1382)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:426)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.os.Handler.handleCallback(Handler.java:605)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.os.Handler.dispatchMessage(Handler.java:92)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.os.Looper.loop(Looper.java:137)
03-15 18:21:48.710: E/AndroidRuntime(13868): at android.app.ActivityThread.main(ActivityThread.java:4456)
03-15 18:21:48.710: E/AndroidRuntime(13868): at java.lang.reflect.Method.invokeNative(Native Method)
03-15 18:21:48.710: E/AndroidRuntime(13868): at java.lang.reflect.Method.invoke(Method.java:511)
03-15 18:21:48.710: E/AndroidRuntime(13868): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
03-15 18:21:48.710: E/AndroidRuntime(13868): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
03-15 18:21:48.710: E/AndroidRuntime(13868): at dalvik.system.NativeStart.main(Native Method)
这是我将listview放入片段的地方。现在我需要将其扩展为使用viewpager，在该片段中有一个viewpaper和其中的三个片段。人们可以水平滑动它，然后选择帧显示到屏幕上。
每个片段都包含自己的listview并从mysql获取数据，任何人都可以教我如何编码...我对此非常困惑。
最佳答案
onCreateView必须仅返回代表片段的视图。 View上的其他操作应在另一个回调中执行，您的代码必须如下所示：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.vending_main, container, false);
}
@Override
public void onViewCreated (View view, Bundle savedInstanceState) {
vendinglist = new ArrayList<HashMap<String, String>>();
listView = (ListView) view.findViewById(R.id.allVendingListView);
listView = getListView();
new get_all_vendingmachine().execute();
}
关于android - 无法使用JSON从MySQL检索数据并将其放入带有 fragment 的ListView中，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/22422186/