有时它显示数据，有时它什么也没显示。
public class HomeFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.home_fragment, container, false);
arraylist1 = new ArrayList<>();
listOfNews = (ListView) view.findViewById(R.id.listView);
runOnUiThread(new Runnable() {
@Override
public void run() {
new ReadJSON().execute("url");
}
});
return view;
}
public class ReadJSON extends AsyncTask<String, Integer, String> {
@Override
protected String doInBackground(String... url) {
String st = readURL(url[0]);
Log.d("st", st);
return st;
}
@Override
protected void onPostExecute(String content) {
try {
JSONObject jsonObject = new JSONObject(content);
JSONArray jsonArray = jsonObject.getJSONArray("data");
for (int i = 0; i < jsonArray.length(); i++) {
Log.d(i+":jsonArray object", jsonArray.toString() + " size= " + jsonArray.length());
JSONObject productObject = jsonArray.getJSONObject(i);
JSONObject img = productObject.getJSONObject("image");
JSONObject da = img.getJSONObject("data");
arraylist1.add(new HotNews(
da.getString("filename"),
productObject.getString("title"),
productObject.getString("article_by"),
productObject.getString("date_publish"),
productObject.getString("short_description")
));
}
Log.d("jsonArray news list1", arraylist1.size() + "");
} catch (JSONException e) {
e.printStackTrace();
}
adapter = new ListViewAdapter(view.getContext(), R.layout.list_view_adapter, arraylist1);
listOfNews.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
private static String readURL(String theUrl) {
StringBuilder content = new StringBuilder();
try {
//create url object
URL url = new URL(theUrl);
//create url connection
URLConnection urlConnection = url.openConnection();
//wrap the urlconnection in a bufferedreader
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
content.append(line + "\n");
}
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
return content.toString();
}
}
public class ListViewAdapter extends ArrayAdapter<HotNews> {
public ListViewAdapter(Context context, int resource, ArrayList<HotNews> arrayList) {
super(context, resource,arrayList);
mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
this.arrayList = arrayList;
this.context = context;
}
@Override
public int getCount() {
return arrayList.size();
}
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
v = mInflater.inflate(R.layout.list_view_adapter, parent, false);
}
image = (ImageView) v.findViewById(R.id.imagetitle);
title = (TextView) v.findViewById(R.id.txtTitle);
doer = (TextView) v.findViewById(R.id.doer);
date = (TextView) v.findViewById(R.id.txtdate);
text = (TextView) v.findViewById(R.id.text);
final HotNews news = getItem(position);
Picasso.with(getContext()).load("url" + news.getImage()).noFade().into(image);
title.setText(news.getTitle());
doer.setText(news.getDoer());
date.setText(news.getDate());
text.setText(news.getContent());
return v;
}
}
答案 0 :(得分：0)
试试这段代码：
public class HomeFragment extends Fragment {
private View view;
private ArrayList<HotNews> arraylist1;
private ListView listOfNews;
private int SUCCESS = 1;
private int FAILS = 0;
private int NO_DATA = 2;
private int ERROR = -1;
private ListViewAdapter adapter;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.home_fragment, container, false);
arraylist1 = new ArrayList<>();
listOfNews = (ListView) view.findViewById(R.id.listView);
adapter = new ListViewAdapter();
listOfNews.setAdapter(adapter);
new ReadJSON().execute("url");
return view;
}
public class ReadJSON extends AsyncTask<String, Integer, Integer> {
@Override
protected Integer doInBackground(String... url) {
String response = readURL(url[0]);
Log.d("response ", response);
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("data");
arraylist1.clear();
if(jsonArray.length()>0) {
for (int i = 0; i < jsonArray.length(); i++) {
Log.d(i + ":jsonArray object", jsonArray.toString() + " size= " + jsonArray.length());
JSONObject productObject = jsonArray.getJSONObject(i);
JSONObject img = productObject.getJSONObject("image");
JSONObject da = img.getJSONObject("data");
arraylist1.add(new HotNews(
da.getString("filename"),
productObject.getString("title"),
productObject.getString("article_by"),
productObject.getString("date_publish"),
productObject.getString("short_description")
));
}
}else{
return NO_DATA;
}
Log.d("jsonArray news list1", arraylist1.size() + "");
} catch (Exception e) {
e.printStackTrace();
return ERROR;
}
return SUCCESS;
}
@Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
Log.d("parseResponse", integer + "");
if(integer==SUCCESS){
adapter.notifyDataSetChanged();
}else if(integer==ERROR){
Toast.makeText(getActivity(),"Server or Exception Error!", Toast.LENGTH_SHORT).show();
}else if(integer==NO_DATA){
Toast.makeText(getActivity(),"No Data!", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(getActivity(),"Some thing went wrong!", Toast.LENGTH_SHORT).show();
}
}
}
class ListViewAdapter extends BaseAdapter{
@Override
public int getCount() {
return arraylist1.size();
}
@Override
public Object getItem(int position) {
return arraylist1.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
ListViewHolder holder;
if (v == null) {
v = LayoutInflater.from(getActivity()).inflate(R.layout.list_view_adapter, parent, false);
holder = new ListViewHolder(v);
v.setTag(holder);
}else{
holder = (ListViewHolder)v.getTag();
}
final HotNews news = arraylist1.get(position);
holder.title.setText(news.getTitle());
holder.doer.setText(news.getDoer());
holder.date.setText(news.getDate());
holder.text.setText(news.getContent());
Picasso.with(getContext()).load("url" + news.getImage()).noFade().into(holder.image);
return v;
}
class ListViewHolder {
private ImageView image;
private TextView title,doer,date,text;
public ListViewHolder(View v){
image = (ImageView) v.findViewById(R.id.imagetitle);
title = (TextView) v.findViewById(R.id.txtTitle);
doer = (TextView) v.findViewById(R.id.doer);
date = (TextView) v.findViewById(R.id.txtdate);
text = (TextView) v.findViewById(R.id.text);
}
}
}
private static String readURL(String theUrl) {
StringBuilder content = new StringBuilder();
try {
//create url object
URL url = new URL(theUrl);
//create url connection
URLConnection urlConnection = url.openConnection();
//wrap the urlconnection in a bufferedreader
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
content.append(line + "\n");
}
bufferedReader.close();
}
catch (Exception e) {
e.printStackTrace();
}
return content.toString();
}
}
答案 1 :(得分：0)
您看到此错误，这会导致整个循环崩溃。您可能正在请求10个对象，但在没有该image属性的第一个对象上，它正在退出。
W / System.err：org.json.JSONException：没有图像值
因此，建议（除了使用Retrofit管理您的JSON API之外）将使用optType()方法而不是JSON对象的getType()方法。
例如，
JSONObject img = productObject.optJSONObject("image");
当img属性不存在时，这会将null设置为"image"。
稍后请注意，如果您在此行中尝试使用img时遇到NullPointerException
JSONObject da = img.getJSONObject("data");