【发布时间】：2016-12-24 11:23:24
【问题描述】：
我一直在四处寻找，试图找出我的代码导致问题的原因。我有一个 GridView，它有一个 ArrayAdapter，它使用 AsyncTask 拉下照片。我可以看到正在更新的项目，但是当我尝试更新适配器时，GridView 似乎没有更新为新视图。
这是完成工作的相关代码...
private void fetchJsonResponse(String url) {
// Pass second argument as "null" for GET requests
JsonObjectRequest req = new JsonObjectRequest(Request.Method.GET,
url + "&api_key=" + API_KEY,
null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray photos = response.getJSONArray("photos");
for(int i = 0; i < photos.length(); i++){
JSONObject object = photos.getJSONObject(i);
String url = object.getString("img_src");
//String id = object.getString("id");
list.add(new ImageItem(null, "Picture", url));
Log.i("Debug 2", url);
}
Log.i("Debug 2", list.get(0).toString());
if(gridViewAdapter != null){
gridViewAdapter.clear();
gridViewAdapter.addAll(list);
gridViewAdapter.notifyDataSetChanged();
gridView.invalidateViews();
} else {
gridViewAdapter = new GridViewAdapter(getActivity(), R.layout.gridview_item, list);
gridView.setAdapter(gridViewAdapter);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.e("Error: ", error.getMessage());
}
});
/* Add your Requests to the RequestQueue to execute */
mRequestQueue.add(req);
}
private class MyAsyncTask extends AsyncTask<String, Void, Void> {
private ProgressDialog progressDialog;
private Context context;
public MyAsyncTask (Context context){
this.context = context;
progressDialog = new ProgressDialog(getActivity());
progressDialog.setMessage("Contacting Rover...");
}
@Override
protected Void doInBackground(String... strings) {
fetchJsonResponse(strings[0]);
return null;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
Toast.makeText(getActivity(), "In Pre Execute", Toast.LENGTH_SHORT).show();
progressDialog.show();
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
progressDialog.dismiss();
}
}
如果可能的话，我非常感谢任何帮助。试图在新年前推出应用程序:)。
也许如果你能告诉我为什么会这样，它就不会再次引起问题，其他人会看到。
编辑：添加了更多代码，在我单击按钮两次后刷新。
private void fetchJsonResponse(String url) {
// Pass second argument as "null" for GET requests
JsonObjectRequest req = new JsonObjectRequest(Request.Method.GET,
url + "&api_key=" + API_KEY,
null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray photos = response.getJSONArray("photos");
list.clear();
for(int i = 0; i < photos.length(); i++){
JSONObject object = photos.getJSONObject(i);
String url = object.getString("img_src");
list.add(new ImageItem(null, "Picture", url));
Log.i("Debug 2", url);
}
Log.i("Debug 2", list.get(0).toString());
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.e("Error: ", error.getMessage());
}
});
/* Add your Requests to the RequestQueue to execute */
mRequestQueue.add(req);
}
private class MyAsyncTask extends AsyncTask<String, Void, Void> {
private ProgressDialog progressDialog;
private Context context;
public MyAsyncTask (Context context){
this.context = context;
progressDialog = new ProgressDialog(getActivity());
progressDialog.setMessage("Contacting Rover...");
pictureAdapter = new PictureAdapter(getActivity(), list);
gridView.setAdapter(pictureAdapter);
}
@Override
protected Void doInBackground(String... strings) {
fetchJsonResponse(strings[0]);
return null;
}
@Override
protected void onPreExecute() {
progressDialog.show();
super.onPreExecute();
Toast.makeText(getActivity(), "In Pre Execute", Toast.LENGTH_SHORT).show();
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
pictureAdapter.updateItemList(list);
gridView.invalidate();
progressDialog.dismiss();
}
}
适配器：
public class PictureAdapter extends BaseAdapter {
private ArrayList<ImageItem> items;
private Context context;
private TextView titleText;
private ImageView itemImage;
public PictureAdapter(Context context, ArrayList<ImageItem> items){
this.context = context;
this.items = items;
}
@Override
public int getCount() {
return items.size();
}
@Override
public Object getItem(int position) {
return items.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = LayoutInflater.from(context).inflate(R.layout.gridview_item, parent, false);
titleText = (TextView) v.findViewById(R.id.text);
itemImage = (ImageView)v.findViewById(R.id.image);
titleText.setText(items.get(position).getTitle());
Picasso.with(context).load(items.get(position).getUrl()).fit().into(itemImage);
return v;
}
public void updateItemList(ArrayList<ImageItem> newItemList){
this.items = newItemList;
notifyDataSetChanged();
}
}
【问题讨论】：
-
您是否遇到任何错误？虽然我不确定，但似乎你正在尝试调用适配器和非 ui 线程上的视图。 responseListener 执行什么线程？
-
@Redman 谢谢！我会看看那个，看看我是否可以使用 ViewHolder。什么都有帮助！没有错误，我什至看到图片网址进来了，所以显示它们在那里。我假设它在后台线程上执行。它在 AsyncTask 中被调用，它也在后台工作，虽然不是？非常感谢您的帮助！
-
如果您在活动中进行操作，请在 runOnUiThread() 方法中更新您的 gridview 或使用将在 ui 线程上运行的处理程序
-
我选择了 if/else 部分，它应该更新 GridView 并放入 onPostExecute，因为它在 UI 线程上运行，但现在似乎根本没有更新......
标签： android gridview android-arrayadapter