也许之前已经回答过，但我找不到任何相同的解决方案，但建议。我正在构建一个应用程序，其中我通过JSON从ListViews数据库填充4 Mysql。这项工作正在以4个片段完成。问题是，当我从数据库中填充2个列表而另外2个只是一些字符串数组数据时，一切正常，但是当我尝试同时填充所有4个列表时，它会崩溃。
错误：
01-04 11:27:25.405 3002-3017/com.order.app.order W/EGL_genymotion﹕ eglSurfaceAttrib not implemented
01-04 11:27:25.405 3002-3017/com.order.app.order W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa31ff7a0, error=EGL_SUCCESS
01-04 11:27:30.619 3002-3002/com.order.app.order I/Choreographer﹕ Skipped 307 frames! The application may be doing too much work on its main thread.
我的片段：
private View rootView;
private ListView lv;
private ArrayAdapter<ProductList> adapter;
private String jsonResult;
private String url = "http://reservations.cretantaxiservices.gr/files/getkafedes.php";
ProgressDialog pDialog;
List<ProductList> customList;
private TextView tv1, tv2;
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.activity_coffees_fragment, container, false);
lv = (ListView)rootView.findViewById(R.id.coffeesListView);
final SwipeRefreshLayout mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.activity_main_swipe_refresh_layout);
ConnectivityManager cm = (ConnectivityManager) getActivity().getSystemService(getActivity().getApplicationContext().CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean network_connected = activeNetwork != null && activeNetwork.isAvailable() && activeNetwork.isConnectedOrConnecting();
if (!network_connected) {
onDetectNetworkState().show();
} else {
if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
accessWebService();
registerCallClickBack();
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
accessWebService();
mSwipeRefreshLayout.setRefreshing(false);
}
});
}
}
return rootView;
}
private AlertDialog onDetectNetworkState() {
AlertDialog.Builder builder1 = new AlertDialog.Builder(getActivity().getApplicationContext());
builder1.setMessage(R.string.wifi_off_message)
.setTitle(R.string.wifi_off_title)
.setNegativeButton(R.string.cancel,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
getActivity().finish();
}
})
.setPositiveButton(R.string.action_settings,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
startActivityForResult((new Intent(
Settings.ACTION_WIFI_SETTINGS)), 1);
getActivity().finish();
}
});
return builder1.create();
}
private void registerCallClickBack() {
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(getActivity().getApplicationContext(), "You have chosen " + customList.get(position).getName(), Toast.LENGTH_SHORT).show();
}
});
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
if (pDialog.isShowing()) {
pDialog.show();
} else {
pDialog.dismiss();
}
if (onDetectNetworkState().isShowing()
&& onDetectNetworkState() != null) {
onDetectNetworkState().show();
} else {
onDetectNetworkState().dismiss();
}
}
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
if (pDialog.isShowing()) {
pDialog.show();
} else {
pDialog.dismiss();
}
if (onDetectNetworkState().isShowing()) {
onDetectNetworkState().show();
} else {
onDetectNetworkState().dismiss();
}
}
}
public class JsonReadTask extends AsyncTask<String, Void, String> {
public JsonReadTask() {
super();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setTitle(R.string.waiting);
pDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pDialog.setMessage(getString(R.string.get_stocks));
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.setInverseBackgroundForced(true);
pDialog.show();
}
@Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
} catch (Exception e) {
getActivity().finish();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
} catch (Exception e) {
getActivity().finish();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
ListDrawer();
pDialog.dismiss();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
task.execute(new String[]{url});
}
public void ListDrawer() {
customList = new ArrayList<ProductList>();
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("kafedes");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String name = jsonChildNode.optString("name");
String price = jsonChildNode.optString("price");
String image = jsonChildNode.optString("image");
customList.add(new ProductList(image, name, price));
}
} catch (Exception e) {
getActivity().finish();
}
adapter = new ProductListAdapter(getActivity().getApplicationContext(), R.layout.list_item, customList);
adapter.notifyDataSetChanged();
lv.setAdapter(adapter);
}
事实上，我正在使用4 AsyncTasks来完成这项工作。任何想法???
修改
我更新了代码，因为我在网上找到了一些但仍然是同样的错误
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if(customList == null){
accessWebService();
}else{
ListDrawer();
}
}
任何帮助将不胜感激!!!
答案 0 :(得分：1)
在这个方法中，你是UI线程
中的实际操作 @Override
protected void onPostExecute(String result) {
ListDrawer();
pDialog.dismiss();
}
您调用ListDrawer();方法，它将执行CPU密集型任务，解析JSON。
它在该方法中抛出异常并在catch块中调用此getActivity().finish();。这就是你回到以前的活动的原因。
尝试在AsynckTask中解析您的JSON，它肯定会解决您的问题。
更新
private View rootView;
private ListView lv;
private ArrayAdapter<ProductList> adapter;
private String jsonResult;
private String url = "http://reservations.cretantaxiservices.gr/files/getkafedes.php";
ProgressDialog pDialog;
List<ProductList> customList;
private TextView tv1, tv2;
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.activity_coffees_fragment, container, false);
lv = (ListView)rootView.findViewById(R.id.coffeesListView);
final SwipeRefreshLayout mSwipeRefreshLayout = (SwipeRefreshLayout) rootView.findViewById(R.id.activity_main_swipe_refresh_layout);
ConnectivityManager cm = (ConnectivityManager) getActivity().getSystemService(getActivity().getApplicationContext().CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean network_connected = activeNetwork != null && activeNetwork.isAvailable() && activeNetwork.isConnectedOrConnecting();
if (!network_connected) {
onDetectNetworkState().show();
} else {
if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
accessWebService();
registerCallClickBack();
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
accessWebService();
mSwipeRefreshLayout.setRefreshing(false);
}
});
}
}
return rootView;
}
private AlertDialog onDetectNetworkState() {
AlertDialog.Builder builder1 = new AlertDialog.Builder(getActivity().getApplicationContext());
builder1.setMessage(R.string.wifi_off_message)
.setTitle(R.string.wifi_off_title)
.setNegativeButton(R.string.cancel,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
getActivity().finish();
}
})
.setPositiveButton(R.string.action_settings,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
startActivityForResult((new Intent(
Settings.ACTION_WIFI_SETTINGS)), 1);
getActivity().finish();
}
});
return builder1.create();
}
private void registerCallClickBack() {
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(getActivity().getApplicationContext(), "You have chosen " + customList.get(position).getName(), Toast.LENGTH_SHORT).show();
}
});
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
if (pDialog.isShowing()) {
pDialog.show();
} else {
pDialog.dismiss();
}
if (onDetectNetworkState().isShowing()
&& onDetectNetworkState() != null) {
onDetectNetworkState().show();
} else {
onDetectNetworkState().dismiss();
}
}
if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
if (pDialog.isShowing()) {
pDialog.show();
} else {
pDialog.dismiss();
}
if (onDetectNetworkState().isShowing()) {
onDetectNetworkState().show();
} else {
onDetectNetworkState().dismiss();
}
}
}
public class JsonReadTask extends AsyncTask<String , Void, List<ProductList>> {
public JsonReadTask() {
super();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setTitle(R.string.waiting);
pDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pDialog.setMessage(getString(R.string.get_stocks));
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.setInverseBackgroundForced(true);
pDialog.show();
}
@Override
protected List<ProductList> doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
customList = new ArrayList<ProductList>();
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("kafedes");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String name = jsonChildNode.optString("name");
String price = jsonChildNode.optString("price");
String image = jsonChildNode.optString("image");
customList.add(new ProductList(image, name, price));
}
return customList;
} catch (Exception e) {
e.printStackTrace();
getActivity().finish();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
} catch (Exception e) {
getActivity().finish();
}
return answer;
}
@Override
protected void onPostExecute(List<ProductList> customList) {
if(customList == null){
Log.d("ERORR", "No result to show.");
return;
}
ListDrawer(customList);
pDialog.dismiss();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
task.execute(new String[]{url});
}
public void ListDrawer(List<ProductList> customList) {
adapter = new ProductListAdapter(getActivity().getApplicationContext(), R.layout.list_item, customList);
adapter.notifyDataSetChanged();
lv.setAdapter(adapter);
}
答案 1 :(得分：1)
您正在访问该字段：
private String jsonResult;
来自后台线程（在AsyncTasks的 doInBackground 方法中）和来自 ListDrawer（）方法中的UI线程：
JSONObject jsonResponse = new JSONObject(jsonResult);
崩溃的最可能原因是UI线程没有看到jsonResult值已设置（因为该字段不易变），并且创建新的JSONObject会引发异常。
解决方案是在异步任务的 doInBackground（）方法中执行响应解析并从中返回ArrayList（编辑：修复编译错误）
@Override
protected ArrayList<ProductList> doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
String jsonResult = inputStreamToString(response.getEntity().getContent()).toString();
ArrayList<ProductList> customList = new ArrayList<ProductList>();
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("kafedes");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String name = jsonChildNode.optString("name");
String price = jsonChildNode.optString("price");
String image = jsonChildNode.optString("image");
customList.add(new ProductList(image, name, price));
}
return customList;
} catch (Exception e) {
return null;
}
}
onPostExecute（）方法：
@Override
protected void onPostExecute(ArrayList<ProductList> result) {
pDialog.dismiss();
if(result == null) {
getActivity().finish();
} else {
adapter = new ProductListAdapter(getActivity().getApplicationContext(), R.layout.list_item, customList);
adapter.notifyDataSetChanged();
lv.setAdapter(adapter);
}
}
最后必须更改AsyncTask的签名：
public class JsonReadTask extends AsyncTask<ArrayList<ProductList>, Void, String> {
...
}