Question

代码

    public class ContactSettings extends Fragment {
    private RecyclerView contactsList;
    private List<ContactsHelper> contacts = new ArrayList<>();
    private LinearLayoutManager linearLayoutManager;
    private ContactsAdapter mAdapter;
       View rootView;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        rootView = inflater.inflate(R.layout.settings_contact, container, false);



        contactsList = (RecyclerView) rootView.findViewById(R.id.usersList);
        //Add the data first
        linearLayoutManager = new LinearLayoutManager(getActivity());
        //and then create a object and pass the lis
        mAdapter = new ContactsAdapter(contacts);

        contactsList.setHasFixedSize(true);
        contactsList.setLayoutManager(linearLayoutManager);
        contactsList.setAdapter(mAdapter);
        mAdapter.notifyDataSetChanged();

        COntacts runner = new COntacts();


        return rootView;
    }

    @Override
    public void onStart(){
        super.onStart();
    }

    private class COntacts extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {
            ContentResolver contentResolver = getActivity().getContentResolver();
            Cursor cursor = contentResolver.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME + " ASC");
            if (cursor != null) {
                if (cursor.getCount() > 0) {
                    while (cursor.moveToNext()) {
                        int hasPhoneNumber = Integer.parseInt(cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)));
                        if (hasPhoneNumber > 0) {
                            String id = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID));
                            String name = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
                            Cursor phoneCursor = contentResolver.query(
                                    ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                                    null,
                                    ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = ?", new String[]{id},
                                    null);
                            if (phoneCursor != null) {
                                if (phoneCursor.moveToNext()) {
                                    String phoneNumber = phoneCursor.getString(phoneCursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));

                                    contacts.add(new ContactsHelper(name, phoneNumber));
                                    phoneCursor.close();
                                }
                            }
                        }
                    }
                }
                cursor.close();
            }
            return "Download failed";
        }


        @Override
        protected void onPostExecute(String result) {
        }
    }

    public void onClick(View view) {

    }
}

它曾经在主线程中工作，但是速度很慢，所以我想到了使用Asynctask，但由于它不是新手，在线教程也不清晰，所以有人可以告诉我这是怎么回事吗？我在后台获取联系人但又不慢........................................ .......................

Answer 1

正如我在代码中看到的那样，您没有在urls中使用doInBackground参数。并且您需要将contacts传递到onPostExecute中运行的UI Thread：

private class COntacts extends AsyncTask<Void, Void, List<ContactsHelper>> {

@Override
protected List<ContactsHelper> doInBackground(Void... urls) {
   List<ContactsHelper> contacts = new ArrayList<>();
   ...
   return contacts
}

@Override
protected void onPostExecute(List<ContactsHelper> result) {
    contacts.addAll(result);
    mAdapter.notifyDataSetChanged();
}

您需要在代码中执行runner对象：

runner.execute()

异步任务未加载数据

1 个答案: