我使用Parse.com作为我的后端存储。我正在维护一些学生的数据，如姓名，卷号，百分比等。我正在通过在微调器中选择卷号来搜索学生的数据。直到现在它工作正常，能够在列表中显示姓名和手机号码。
但如果在数据库中找不到特定卷号的数据，如何显示Toast。我正在使用这个代码，如果找到数据会得到很好的结果但是如果没有找到结果我无法显示Toast。
我的代码在这里：
s.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
final String result=list.get(position);
ParseQueryAdapter.QueryFactory<AnywallPost> factory =
new ParseQueryAdapter.QueryFactory<AnywallPost>() {
public ParseQuery<AnywallPost> create() {
final ParseQuery<AnywallPost> query = AnywallPost.getQuery();
query.include("user");
query.orderByDescending("createdAt");
query.whereEqualTo("RollNumber",result);
/*
//Added by Tara
query.findInBackground(new FindCallback<AnywallPost>() {
@Override
public void done(List<AnywallPost> list, com.parse.ParseException e) {
if (list.size()!=0){
Toast.makeText(getApplicationContext(),"Found",Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(getApplicationContext(),"not Found",Toast.LENGTH_SHORT).show();
}
}
}); */
return query;
}
};
// Set up the query adapter
postsQueryAdapter = new ParseQueryAdapter<AnywallPost>(SearchStudentList.this, factory) {
@Override
public View getItemView(AnywallPost post, View view, ViewGroup parent) {
if (view == null) {
view = View.inflate(getContext(), R.layout.listview_item, null);
}
TextView usernameView = (TextView) view.findViewById(R.id.search_username_TV);
TextView mobileView = (TextView) view.findViewById(R.id.search_mobile_TV);
usernameView.setText(post.getUser().getUsername());
mobileView.setText(post.getTextMobile());
return view;
}
};
// Disable automatic loading when the adapter is attached to a view.
postsQueryAdapter.setAutoload(false);
// Disable pagination, we'll manage the query limit ourselves
postsQueryAdapter.setPaginationEnabled(false);
ListView postsListView = (ListView) findViewById(R.id.search_student_LV);
postsListView.setAdapter(postsQueryAdapter);
postsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
final AnywallPost item = postsQueryAdapter.getItem(position);
selectedPostObjectId = item.getObjectId();
String selectedpostMobile = item.getTextMobile();
Toast.makeText(getApplicationContext(), selectedpostMobile, Toast.LENGTH_SHORT).show();
}
});
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
这是我的Log cat，请检查一下：
03-22 17:19:15.682 20634-
20644/com.example.avenirlabs_pc1.testblooddonorapp W/art﹕
Suspending all threads took: 328.725ms
03-22 17:19:15.886 20634-
20634/com.example.avenirlabs_pc1.testblooddonorapp
D/AndroidRuntime﹕ Shutting down VM
03-22 17:19:15.900 20634-
20634/com.example.avenirlabs_pc1.testblooddonorapp
E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.avenirlabs_pc1.testblooddonorapp, PID: 20634
java.lang.RuntimeException: This query has an outstanding network connection. You have to wait until it's done.
at com.parse.ParseQuery.checkIfRunning(ParseQuery.java:272)
at com.parse.ParseQuery.doWithRunningCheck(ParseQuery.java:871)
at com.parse.ParseQuery.doInBackground(ParseQuery.java:895)
at com.parse.ParseQuery.findInBackground(ParseQuery.java:930)
at com.parse.ParseQueryAdapter.loadObjects(ParseQueryAdapter.java:347)
at com.parse.ParseQueryAdapter.loadObjects(ParseQueryAdapter.java:327)
at com.example.avenirlabs_pc1.testblooddonorapp.SearchDonorList.doListQuery(SearchDonorList.java:673)
at com.example.avenirlabs_pc1.testblooddonorapp.SearchDonorList.onLocationChanged(SearchDonorList.java:633)
at com.google.android.gms.location.internal.zzk$zzb.handleMessage(Unknown Source)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5343)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
03-22 17:19:16.087 20634-
20649/com.example.avenirlabs_pc1.testblooddonorapp W/art﹕ Suspending
all threads took: 7.403ms
03-22 17:19:16.100 20634-
20649/com.example.avenirlabs_pc1.testblooddonorapp I/art﹕ Background
sticky concurrent mark sweep GC freed 23032(1037KB) AllocSpace
objects, 5(652KB) LOS objects, 10% free, 17MB/19MB, paused 9.673ms
total 162.031ms
03-22 17:19:17.267 20634-
20649/com.example.avenirlabs_pc1.testblooddonorapp I/art﹕ Background
partial concurrent mark sweep GC freed 34071(1339KB) AllocSpace
objects, 48(2MB) LOS objects, 39% free, 15MB/25MB, paused 2.722ms
total 123.637ms