如何让自定义适配器中的 sharedpreferences 获取我的 ArrayList 的最新值？

Question

我在我的活动的onCreate 中使用Volley，它在我的服务器上获得string，然后我将这个string 转换为arraylist,checkedContactsAsArrayList，并将它传递给我的custom adapter 使用 sharedpreferences，它与 listview 中的 arraylist 一起使用。

但是custom adapter 不断在sharedpreferences 中获取前一个arraylist，而不是我刚刚从服务器获得的那个。 Volley 调用为时已晚或其他什么 - 我可以在 logcat 中看到最新值是 put，在它们是 got 之后，如果你知道我的意思的话。

例如：

VolleyCall 1 putString: 1,2,3
VolleyCall 2 putString: 4,5,6
VolleyCall 3 putString: 7,8,9

Custom Adapter 1 getString: gets values of the last time app was used
Custom Adapter 2 getString: 1,2,3
Custom Adapter 3 getString: 4,5,6

知道如何解决这个问题吗？我可以尝试在我的自定义适配器的getView 中进行Volley 调用，但我在 Stackoverflow 上读过这是不好的做法。

以下是我的代码的相关部分 - 我已对其进行了精简，因为其中有很多与此问题无关的内容。

这是我的活动代码，ViewContact：

public class ViewContact extends AppCompatActivity implements android.widget.CompoundButton.OnCheckedChangeListener  {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(activity_view_contact);


        //selectPhoneContacts is an empty array list that will hold our SelectPhoneContact info
        selectPhoneContacts = new ArrayList<SelectPhoneContact>();


        listView = (ListView) findViewById(R.id.listviewPhoneContacts);


        StringRequest stringRequest = new StringRequest(Request.Method.POST, ViewContact_URL,
                new Response.Listener<String>() {

                    @Override
                    public void onResponse(String response) {

                        //toast the response of ViewContact.php, which has been converted to a
                        //JSON object by the Php file with JSON encode
                        Toast.makeText(ViewContact.this, "OnResponse is" + response, Toast.LENGTH_LONG).show();
                        System.out.println("ViewContact: And the response is " + response);


                        try {

                            //checkedContacts is a String
                            String checkedContacts = responseObject.getString("checkedcontacts");

                            //convert the checkedContacts string to an arraylist

                            checkedContactsAsArrayList = new ArrayList<String>(Arrays.asList(checkedcontacts.split(",")));
                            System.out.println("ViewContact: checkedContactsAsArrayList is " + checkedContactsAsArrayList);


                            //we want to bring the checkedContactsAsArrayList array list to our SelectPhoneContactAdapter.
                            // It looks like Shared Preferences
                            //only works easily with strings so best way to bring the array list in Shared Preferences is with
                            //Gson.
                            //Here, we PUT the arraylist into the sharedPreferences

                    SharedPreferences sharedPreferencescheckedContactsAsArrayList = PreferenceManager.getDefaultSharedPreferences(getApplication());
                    SharedPreferences.Editor editorcheckedContactsAsArrayList = sharedPreferencescheckedContactsAsArrayList.edit();
                    Gson gsoncheckedContactsAsArrayList = new Gson();
                    String jsoncheckedContactsAsArrayList = gsoncheckedContactsAsArrayList.toJson(checkedContactsAsArrayList);
                    editorcheckedContactsAsArrayList.putString("checkedContactsAsArrayList", jsoncheckedContactsAsArrayList);
                    editorcheckedContactsAsArrayList.commit();
                    System.out.println("ViewContact: jsoncheckedContactsAsArrayList is " + jsoncheckedContactsAsArrayList);


                        } catch (JSONException e) {
                            e.printStackTrace();
                            Toast.makeText(getApplicationContext(),
                                    "Error: " + e.getMessage(),
                                    Toast.LENGTH_LONG).show();
                        }



                    }

                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(ViewContact.this, error.toString(), Toast.LENGTH_LONG).show();

                    }

                }) {
            @Override
            protected Map<String, String> getParams() {
                Map<String, String> params = new HashMap<String, String>();
                //we are posting review_id into our ViewContact.php file, which
                //we get when a row is clicked in populistolistview
                //to get matching details
                params.put("review_id", review_id);
                return params;

            }

        };
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(stringRequest);



    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

        //checkBoxforContact.setChecked(true);


    }


    //******for the phone contacts in the listview

    // Load data in background
    class LoadContact extends AsyncTask<Void, Void, Void> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... voids) {

            //we want to delete the old selectContacts from the listview when the Activity loads
            //because it may need to be updated and we want the user to see the updated listview,
            //like if the user adds new names and numbers to their phone contacts.
            selectPhoneContacts.clear();


                SelectPhoneContact selectContact = new SelectPhoneContact();


                selectContact.setName(phoneNameofContact);


            }


            return null;


        }


        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);




            adapter = new SelectPhoneContactAdapter(selectPhoneContacts, ViewContact.this,0);



            listView.setAdapter(adapter);


            adapter.notifyDataSetChanged();


        }
    }


    @Override
    protected void onResume() {

        super.onResume();

        // getPrefs();

        ViewContact.LoadContact loadContact = new ViewContact.LoadContact();


        loadContact.execute();

        Toast.makeText(ViewContact.this, "resuming!", Toast.LENGTH_SHORT).show();


    }

}

还有我的custom adapter，SelectPhoneContactAdapter：

public class SelectPhoneContactAdapter extends BaseAdapter {

//define a list made out of SelectPhoneContacts and call it theContactsList
public List<SelectPhoneContact> theContactsList;
//define an array list made out of SelectContacts and call it arraylist
private ArrayList<SelectPhoneContact> arraylist;
Context _c;
ArrayList<String> MatchingContactsAsArrayList;
ArrayList<String> checkedContactsAsArrayList;
ArrayList <String> allNamesofContacts;
String contactToCheck;
//we will run through different logic in this custom adapter based on the activity that is passed to it
private int whichactivity;

String phoneNumberofContact;
String[] phoneNumberofContactStringArray;
String ContactsString;

Intent intent;


public SelectPhoneContactAdapter(final List<SelectPhoneContact> selectPhoneContacts, Context context, int activity) {
    theContactsList = selectPhoneContacts;
    _c = context;
    this.arraylist = new ArrayList<SelectPhoneContact>();
    this.arraylist.addAll(theContactsList);
    whichactivity = activity;


    //we are fetching the array list checkedContactsAsArrayList, created in ViewContact.
    //with this we will put a tick in the checkboxes of contacts the review is being shared with

    SharedPreferences sharedPreferencescheckedContactsAsArrayList = PreferenceManager.getDefaultSharedPreferences(_c);
    Gson gsoncheckedContactsAsArrayList = new Gson();
    String jsoncheckedContactsAsArrayList = sharedPreferencescheckedContactsAsArrayList.getString("checkedContactsAsArrayList", "");
    Type type2 = new TypeToken<ArrayList<String>>() {
    }.getType();
    checkedContactsAsArrayList = gsoncheckedContactsAsArrayList.fromJson(jsoncheckedContactsAsArrayList, type2);
    System.out.println("SelectPhoneContactAdapter checkedContactsAsArrayList :" + checkedContactsAsArrayList);

                                 }
}



@Override
public int getCount() {
    return arraylist.size();
}

@Override
public Object getItem(int i) {
    return arraylist.get(i);
}

@Override
public long getItemId(int i) {
    return i;
}



static class ViewHolder {
    //In each cell in the listview show the items you want to have
    //Having a ViewHolder caches our ids, instead of having to call and load each one again and again
    TextView title, phone;
    CheckBox check;
    Button invite;
}


@Override
public View getView(final int i, View convertView, ViewGroup viewGroup) {


    //this is the SelectPhoneContact object; consists of textboxes, buttons, checkbox
    final SelectPhoneContact data = (SelectPhoneContact) arraylist.get(i);

    ViewHolder holder = null;

    if (convertView == null) {

        //if there is nothing there (if it's null) inflate the view with the layout
        LayoutInflater li = (LayoutInflater) _c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = li.inflate(R.layout.phone_inflate_listview, null);

        holder = new ViewHolder();
        //So, for example, title is cast to the name id, in phone_inflate_listview,
        //phone is cast to the id called no etc
        holder.title = (TextView) convertView.findViewById(R.id.name);
        holder.phone = (TextView) convertView.findViewById(R.id.no);
        holder.invite = (Button)  convertView.findViewById(R.id.btnInvite);
        holder.check = (CheckBox) convertView.findViewById(R.id.checkBoxContact);


        convertView.setTag(holder);

    } else {

        holder = (ViewHolder) convertView.getTag();

    }


    //in the listview for contacts, set the name
    holder.title.setText(data.getName());

    //in the listview for contacts, set the number
    holder.phone.setText(data.getPhone());




    holder.check.setTag(data);

    return convertView;

    }

}

Answer 1

打电话给这个：loadContact.execute(); 致电.commit();后

ViewContact.LoadContact loadContact = new ViewContact.LoadContact();
loadContact.execute();