我将jSon数组数据存储在ArrayList<Model>中。我想在其他类中使用此ArrayList<Model>，因此我创建了一个返回ArrayList的方法。但总是我变得无效。
类
public class SearchJobAsync extends AsyncTask<String, String, String> {
private String response;
Context c;
SearchModel data;
ArrayList<SearchModel> values;
public SearchJobAsync(Context c) {
this.c = c;
}
@Override
protected void onPreExecute() {
super.onPreExecute ();
CommonFunctions.showProgress (c, "Please Wait...", true);
}
@Override
protected void onPostExecute(String s) {
values = new ArrayList<SearchModel> ();
super.onPostExecute (s);
if (!s.trim ().contains ("Table")) {
Crouton.makeText ((android.app.Activity) c, "Nothing found", Style.INFO).show ();
} else {
try {
JSONObject jsonObject = new JSONObject (s);
JSONObject NewDataSet = jsonObject.getJSONObject ("NewDataSet");
if (NewDataSet.get ("Table") instanceof JSONObject) {
JSONObject table = NewDataSet.getJSONObject ("Table");
data = new SearchModel (table.getString ("Job_Category"), table.getString ("Min_Exp"), table.getString ("Max_Exp"), table.getString ("Posted_On"), table.getString ("Candidate_Counts"), table.getString ("Applications"), table.getString ("No_Of_Pos"), table.getString ("Job_Desc"), table.getString ("Job_Type"), table.getString ("Job_Hours"), table.getString ("Job_Status"), table.getString ("Job_Exp_Date"), table.getString ("Address"), table.getString ("Gender_Name"), table.getString ("Religion_Name"), table.getString ("Exp_Summary"), table.getString ("IJob_Request_ID"), table.getString ("Requestor_Name"));
values.add (data);
} else if (NewDataSet.get ("Table") instanceof JSONArray) {
JSONArray tableArray = NewDataSet.getJSONArray ("Table");
for (int i = 0; i < tableArray.length (); i++) {
JSONObject table = tableArray.getJSONObject (i);
data = new SearchModel (table.getString ("Job_Category"), table.getString ("Min_Exp"), table.getString ("Max_Exp"), table.getString ("Posted_On"), table.getString ("Candidate_Counts"), table.getString ("Applications"), table.getString ("No_Of_Pos"), table.getString ("Job_Desc"), table.getString ("Job_Type"), table.getString ("Job_Hours"), table.getString ("Job_Status"), table.getString ("Job_Exp_Date"), table.getString ("Address"), table.getString ("Gender_Name"), table.getString ("Religion_Name"), table.getString ("Exp_Summary"), table.getString ("IJob_Request_ID"), table.getString ("Requestor_Name"));
values.add (data);
}
}
} catch (JSONException e) {
e.printStackTrace ();
}
}
CommonFunctions.showProgress (c, "", false);
Intent i = new Intent (c, SearchJobListActivity.class);
c.startActivity (i);
}
@Override
protected String doInBackground(String... s) {
response = HttpRequest.post ("https://beta135.hamarisuraksha.com/web/WebService/HsJobService.asmx/FindJobForVendor").send ("Vendor_IEntity_Code=" + "34588A34-E969-4723-84FE-E5409B66A5B7" + "&Job_Code=" + "&Job_Category=1" + "&Exp_Years_From=0" + "&Exp_Months_From=0" + "&Exp_Years_To=0" + "&Exp_Months_To=0").body ();
response = response.replaceAll ("<[^>]*>", "").replaceAll ("\n", "");
Log.e ("Search Jobs", "" + response);
return response;
}
public ArrayList<SearchModel> getList(){
return values;
}
}
我正在使用arraylist的类
public class SearchJobList extends ListFragment {
private View view;
private ListView lvSearchJobs;
private ArrayList<SearchModel> data;
SearchJobCustomList customList;
SearchJobAsync searchJobAsync;
private Context c;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate (R.layout.search_job_lists, container, false);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated (savedInstanceState);
c = getActivity ();
lvSearchJobs = (ListView) getActivity ().findViewById (android.R.id.list);
data = new ArrayList<SearchModel> ();
searchJobAsync = new SearchJobAsync (c);
data = searchJobAsync.getList ();
customList = new SearchJobCustomList (c, data);
setListAdapter (customList);
}
}
我在使用.execute（）方法的类
public class SearchJobsFragment extends Fragment implements View.OnClickListener {
private View view;
private Spinner spCategory;
private Button btSearch;
private Spinner spToYrs;
private Spinner spFromMonths;
private Spinner spFromYrs;
private Spinner spToMonths;
private EditText etJobCode;
private String[] yrsArray, monthArray, professionArray;
private ArrayAdapter<String> toYrs, toMonths, profession;
private Context c;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate (R.layout.search_jobs_frag, container, false);
return view;
}
private void initialize() {
c = getActivity ();
spCategory = (Spinner) getActivity ().findViewById (R.id.sp_category);
btSearch = (Button) getActivity ().findViewById (R.id.bt_search);
spToYrs = (Spinner) getActivity ().findViewById (R.id.sp_to_yrs);
spFromMonths = (Spinner) getActivity ().findViewById (R.id.sp_from_months);
spFromYrs = (Spinner) getActivity ().findViewById (R.id.sp_from_yrs);
spToMonths = (Spinner) getActivity ().findViewById (R.id.sp_to_months);
etJobCode = (EditText) getActivity ().findViewById (R.id.et_job_code);
btSearch.setOnClickListener (this);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated (savedInstanceState);
initialize ();
spinnerSetup ();
}
private void spinnerSetup() {
//for to/from yrs
yrsArray = getResources ().getStringArray (R.array.Experience_yrss);
toYrs = new ArrayAdapter<String> (c, R.layout.spinner_textview, yrsArray);
toYrs.setDropDownViewResource (android.R.layout.simple_list_item_single_choice);
spToYrs.setAdapter (toYrs);
spFromYrs.setAdapter (toYrs);
// for to/from months
monthArray = getResources ().getStringArray (R.array.Experience_months);
toMonths = new ArrayAdapter<String> (c, R.layout.spinner_textview, monthArray);
toMonths.setDropDownViewResource (android.R.layout.simple_list_item_single_choice);
spToMonths.setAdapter (toMonths);
spFromMonths.setAdapter (toMonths);
//for category
professionArray = getResources ().getStringArray (R.array.Profession);
Arrays.sort (professionArray, 1, professionArray.length);
profession = new ArrayAdapter<String> (c, R.layout.spinner_textview, professionArray);
profession.setDropDownViewResource (android.R.layout.simple_list_item_single_choice);
spCategory.setAdapter (profession);
}
@Override
public void onClick(View view) {
SearchJobAsync searchJobAsync = new SearchJobAsync (c);
searchJobAsync.execute ();
}
}
在getList()方法中，我将返回值，但它始终显示为null。
答案 0 :(得分：0)
如果您在onPostExecute()被执行之前尝试访问，则列表将为空。因为它尚未初始化。因此，在尝试访问列表之前，请确保完成任务。
在显示进度时，最好将本地List<SearchModel>引用传递给SearchJobAsync的构造函数。只有在隐藏对话框后，此引用才有值。
因此添加一个构造函数，如：
public SearchJobAsync(Context c, List<SearchModel> values) {
this.c = c;
this.values=values;
}
在你的活动中
List<SearchModel> myListVar;
new SearchJobAsync(MyActivity.this, myListVar);
答案 1 :(得分：0)
您在任务完成之前调用getList方法（在任务完成后调用方法onPostExecute）。当列表准备就绪时，您必须通知您的上下文（活动，片段）。
答案 2 :(得分：0)
问题在于以下几行
data = new ArrayList<SearchModel> ();
searchJobAsync = new SearchJobAsync (c);
data = searchJobAsync.getList ();
您没有为AsyncTask调用execute（）方法，如下所示
new DownloadFilesTask().execute(url1, url2, url3);
如果没有此onPreExecute，则不会调用doInBackground和onPostExecute方法。这是您将数据作为null的原因。
还有一个建议，在你的onPostExecute（）中，你正在调用startActivity（）方法
Intent i = new Intent (c, SearchJobListActivity.class);
c.startActivity (i);
但是你想要SearchJobList片段中的ArrayList值。 AsyncTask成功执行后，屏幕上将显示新活动。你需要解决这个问题。
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