我想把类中的Arraylist传递给扩展ListFragments的类。但每当我调用它时，我都会得到空指针异常。
异步类
public class SearchJobAsync extends AsyncTask<String, String, String> {
private String response;
Context c;
SearchModel data;
ArrayList<SearchModel> values;
getArrayList list;
public interface getArrayList {
public void getList(ArrayList<SearchModel> data);
}
public SearchJobAsync(Context c, ArrayList<SearchModel> values, getArrayList list) {
this.c = c;
this.values = values;
this.list = list;
}
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);
}
}
if (values.size () > 0) {
list.getList (values);
}
} 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;
}
}
ListFragment类
public class SearchJobList extends ListFragment implements SearchJobAsync.getArrayList {
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.execute ();
searchJobAsync = new SearchJobAsync (c, data, this);
}
@Override
public void getList(ArrayList<SearchModel> data) {
customList = new SearchJobCustomList (c, data);
setListAdapter (customList);
}
}
我在logcat
所说的这行上遇到错误list.getList (values);
和
public class SearchJobAsync extends AsyncTask<String, String, String>
logcat的
06-26 13:03:46.256 31713-31713/com.jobs_on_call_fragments E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.jobs_on_call_fragments.AsyncTasks.SearchJobAsync.onPostExecute(SearchJobAsync.java:83)
at com.jobs_on_call_fragments.AsyncTasks.SearchJobAsync.onPostExecute(SearchJobAsync.java:25)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:213)
at android.app.ActivityThread.main(ActivityThread.java:4787)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
at dalvik.system.NativeStart.main(Native Method)
使用此Async的其他活动
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 ();
}
}
答案 0 :(得分：0)
尝试交换这一行。
searchJobAsync.execute ();
searchJobAsync = new SearchJobAsync (c, data, this);
更新后的问题： 我确定SearchJobsFragment会导致错误。 有两个原因：
1你无法运行
searchJobAsync.execute ();
searchJobAsync = new SearchJobAsync (c, data, this);
按此顺序，它会在execute方法中导致空指针异常。所以，我认为SearchJobList类从未在你的项目中使用过。
2我使用具有类似行为的SearchJobAsync和ListFragment类构建小型测试项目，并且它工作正常。所以，SearchJobsFragment中存在问题。
您需要从onClick方法调用SearchJobAsync（Context，ArrayList＆lt;＆gt;，getArrayList）构造函数。否则，SearchJobAsync中的列表变量将保持为空并导致异常。
答案 1 :(得分：0)
<强>问题：
implements SearchJobAsync.getArrayList
你试图在一个非静态的不同类上调用一个接口，这就是为什么编译器遇到麻烦的原因
<强>溶液
让getArrayList成为static interface
static interface getArrayList {
public void getList(ArrayList<SearchModel> data);
}
编辑：
如果您从其他活动中调用它，则调用空指针检查
<强>样品：
if (values.size () > 0) {
if(list != null)
list.getList (values);
}