适配器notifyDataSetChanged后Android更新imageview

Question

在我的适配器和从服务器检索数据时，我可以重新加载recyclerview，在我的recyclerview项中，我有简单的imageView，在从服务器检索到数据和映像状态后，我必须更改其中的映像，但我的适配器在重新加载数据和notifyDataSetChanged后无法更新映像。

我可以通过syncByServer从服务器检索数据，我的方法是通过以下代码更新数据库：

ContactLists exists_row = realm.where(ContactLists.class).equalTo("mobile_number", mobileNumber).findFirst();
realm.beginTransaction();
if (exists_row != null) {
exists_row.setIsRegistered("1");
} else {
exists_row.setIsRegistered("0");
}
realm.commitTransaction();

如果setIsRegistered必须是更改图像状态，如果setIsRegistered为1，则必须从Drawable设置为setImageDrawable。

主要活动：

realm = Realm.getDefaultInstance();
recyclerView = (RecyclerView) findViewById(R.id.rcontactLists);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new ContactsAdapter(results, getApplication());
recyclerView.setAdapter(adapter);
long contact_count = realm.where(ContactLists.class).count();
if (contact_count > 0) {
reloadFromDatabase();
} else {
long count = Utils.getLocalContactsList(getContentResolver(), realm);
if (count > 0) {
reloadFromDatabase();
}
syncByServer();
}
/*----------------------------------------------------------*/
private void reloadFromDatabase() {
results = realm.where(ContactLists.class).findAll();
adapter.setData(results);
adapter.notifyDataSetChanged();
}
private void syncByServer() {
long count = Utils.getLocalContactsList(getContentResolver(), realm);
if (count > 0) {
showProgressDialog();
results = realm.where(ContactLists.class).findAll();
ArrayList wordList = new ArrayList<>();
if (results.size() > 0) {
for (ContactLists c : results) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("contactName", c.getContact_name());
map.put("mobileNumber", c.getMobile_number());
wordList.add(map);
}
}
String fetch_server_url = SampleApplication.getHostAddress() + "clientSyncContatcLists";
HttpsTrustManager.allowAllSSL();
JsonArrayRequest req = new JsonArrayRequest(fetch_server_url, new JSONArray(wordList),
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
for (int i = 0; i < response.length(); i++) {
try {
JSONObject jsonObject   = response.getJSONObject(i);
String     mobileNumber = jsonObject.getString("mobileNumber");
ContactLists exists_row = realm.where(ContactLists.class).equalTo("mobile_number", mobileNumber).findFirst();
realm.beginTransaction();
if (exists_row != null) {
exists_row.setIsRegistered("1");
} else {
exists_row.setIsRegistered("0");
}
realm.commitTransaction();
} catch (JSONException e) {
e.printStackTrace();
}
}
results = realm.where(ContactLists.class).findAll();
adapter.setData(results);
adapter.notifyDataSetChanged();
progressDialog.dismiss();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
//Log.e
}
});
EpayApplication.getInstance().addToRequestQueue(req);
} else {
Utils.toast(Utils.getString(R.string.there_is_no_contacts), getBaseContext());
}
}

我的适配器

public class ContactsAdapter extends RecyclerView.Adapter<CustomContactsViewHolder> {
List<ContactLists> list = Collections.emptyList();
Context context;
public ContactsAdapter(List<ContactLists> list, Context context) {
this.list = list;
this.context = context;
}
@Override
public CustomContactsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View                     v      = LayoutInflater.from(parent.getContext()).inflate(R.layout.contact_item, parent, false);
CustomContactsViewHolder holder = new CustomContactsViewHolder(v);
return holder;
}
@Override
public void onBindViewHolder(CustomContactsViewHolder holder, int position) {
holder.title.setText(list.get(position).getContact_name());
holder.description.setText(list.get(position).getMobile_number());
if (list.get(position).getIsRegistered().equals("1"))
holder.img_logo.setImageDrawable(context.getResources().getDrawable(R.drawable.epay_logo));
else
holder.img_logo.setVisibility(View.INVISIBLE);
}
@Override
public int getItemCount() {
return list.size();
}
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
public void setData(List<ContactLists> list) {
this.list = list;
}
}

Answer 1

您可能遇到了一个NPE。发布的代码片段保证exists_row在else分支中为null。

if (exists_row != null) {
exists_row.setIsRegistered("1");
} else {
exists_row.setIsRegistered("0");
}

还有一个问题，为什么IDE没有警告您？

ORexists_row从不为null。我认为这很可能是因为你没有写应用程序崩溃。调试这些行，看看到底发生了什么。