Android的奇怪的错误 [英] Android strange error
本文介绍了Android的奇怪的错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我做了一个列表视图的应用程序，然后创建一个新的与片段，并要实现列表视图支离破碎。但是当我做我得到一个奇怪的错误。
公共类片段1片段扩展{
私人的ArrayList＆LT; FeedItem＆GT; feedList = NULL;
私人进度进度= NULL;
私人的ListView feedListView = NULL; @覆盖
公共查看onCreateView（LayoutInflater充气器，容器的ViewGroup，捆绑savedInstanceState）{
查看rootView = inflater.inflate（R.layout.list_row_layout，集装箱，FALSE）; 进度=（进度）rootView.findViewById（R.id.progressBar）;
字符串URL =;
新DownloadFilesTask（）执行（URL）;
返回rootView;
} 公共无效updateList（）{
。feedListView =（ListView控件）getActivity（）findViewById（R.id.custom_list）;
feedListView.setVisibility（View.VISIBLE）;
progressbar.setVisibility（View.GONE）; ** feedListView.setAdapter（新CustomListAdapter（这一点，feedList））; **
feedListView.setOnItemClickListener（新OnItemClickListener（）{ @覆盖
公共无效onItemClick（适配器视图＆LT;＆gt;一种，视图V，INT位置，长的id）{
对象o = feedListView.getItemAtPosition（位置）;
FeedItem newsData =（FeedItem）O; **意向意图=新意图（FeedListActivity.this，FeedDetailsActivity.class）**
intent.putExtra（饲料，newsData）;
startActivity（意向）;
}
}）;
} 公共类DownloadFilesTask扩展的AsyncTask＆LT;字符串，整数，太虚＆GT; { @覆盖
保护无效onProgressUpdate（整数...值）{
} @覆盖
保护无效onPostExecute（虚空结果）{
如果（NULL！= feedList）{
updateList（）;
}
} @覆盖
保护无效doInBackground（字符串... PARAMS）{
字符串URL =参数[0]; // URL从获取JSON字符串
JSONObject的JSON = getJSONFromUrl（URL）; //解析JSON数据
parseJson（JSON）;
返回null;
}
}
公众的JSONObject getJSONFromUrl（字符串URL）{
InputStream为= NULL;
JSONObject的jObj = NULL;
JSON字符串= NULL; //使HTTP请求
尝试{
// defaultHttpClient
DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
HttpPost httpPost =新HttpPost（URL）; HTT presponse HTT presponse = httpClient.execute（httpPost）;
HttpEntity httpEntity = HTT presponse.getEntity（）;
是= httpEntity.getContent（）; 读者的BufferedReader =新的BufferedReader（新的InputStreamReader（
是，ISO-8859-1），8）;
StringBuilder的SB =新的StringBuilder（）;
串线= NULL;
而（（行= reader.readLine（））！= NULL）{
sb.append（行+\\ n）;
}
is.close（）;
JSON = sb.toString（）;
}赶上（UnsupportedEncodingException五）{
e.printStackTrace（）;
}赶上（ClientProtocolException E）{
e.printStackTrace（）;
}赶上（IOException异常五）{
e.printStackTrace（）;
} 尝试{
jObj =新的JSONObject（JSON）;
}赶上（JSONException E）{
Log.e（JSON解析器，错误分析数据+ e.toString（））;
} //返回JSON字符串
返回jObj; } 公共无效parseJson（JSON的JSONObject）{
尝试{ //解析JSON对象
如果（json.getString（身份）。equalsIgnoreCase（OK））{
JSONArray帖= json.getJSONArray（上岗）; feedList =新的ArrayList＆LT; FeedItem＆GT;（）; 的for（int i = 0; I＆LT; posts.length（）;我++）{
JSONObject的岗位=（JSONObject的）posts.getJSONObject（I）
FeedItem项目=新FeedItem（）;
item.setTitle（post.getString（标题））;
item.setDate（post.getString（说明））;
item.setId（post.getString（ID））;
item.setUrl（post.getString（URL））;
item.setContent（post.getString（说明））;
JSONArray附件= post.getJSONArray（附件）; 如果（零=附件＆放大器;！＆放大器; attachments.length（）大于0）{
JSONObject的附件= attachments.getJSONObject（0）;
如果（附件！= NULL）
item.setAttachmentUrl（attachment.getString（URL））;
} feedList.add（项目）;
}
}
}赶上（JSONException E）{
e.printStackTrace（）;
}
} }
问题是在这行
feedListView.setAdapter（新CustomListAdapter（这一点，feedList））;
意向意图=新意图（FeedListActivity.this，FeedDetailsActivity.class）;
在该行多个标记
- 行断点：片段1 [行：57] - updateList（）
- 构造CustomListAdapter（片段1，ArrayList的＆LT; FeedItem＆gt;）的
未定义
类型FeedListActivity没有外围实例是在范围访问
CustomListAdapter：
公共类CustomListAdapter延伸BaseAdapter { 私人的ArrayList＆LT; FeedItem＆GT;的ListData; 私人LayoutInflater layoutInflater; 私人语境mContext; 公共CustomListAdapter（上下文的背景下，ArrayList的＆LT; FeedItem＆GT;的ListData）{
this.listData =的ListData;
layoutInflater = LayoutInflater.from（上下文）;
mContext =背景;
} @覆盖
公众诠释的getCount（）{
返回listData.size（）;
} @覆盖
公共对象的getItem（INT位置）{
返回listData.get（位置）;
} @覆盖
众长getItemId（INT位置）{
返回的位置;
} 公共查看getView（INT位置，查看convertView，父母的ViewGroup）{
ViewHolder持有人;
如果（convertView == NULL）{
convertView = layoutInflater.inflate（R.layout.list_row_layout，NULL）;
持有人=新ViewHolder（）;
holder.headlineView =（TextView中）convertView.findViewById（R.id.title）;
holder.reportedDateView =（TextView中）convertView.findViewById（R.id.date）;
holder.imageView =（ImageView的）convertView.findViewById（R.id.thumbImage）;
convertView.setTag（保持器）;
}其他{
支架=（ViewHolder）convertView.getTag（）;
} FeedItem newsItem =（FeedItem）listData.get（位置）;
holder.headlineView.setText（newsItem.getTitle（））;
holder.reportedDateView.setText（newsItem.getDate（））; 如果（holder.imageView！= NULL）{
新ImageDownloaderTask（holder.imageView）.execute（newsItem.getAttachmentUrl（））;
} 返回convertView;
} 静态类ViewHolder {
TextView的headlineView;
TextView的reportedDateView;
ImageView的ImageView的;
}
}
解决方案
在此行 feedListView.setAdapter（新CustomListAdapter（这一点，feedList））; 只是替换此 getActivity（）;
I have made an listview application, then i created a new one with fragments and want to implement listview to fragments. But when i do i got an strange error.
public class Fragment1 extends Fragment {
private ArrayList<FeedItem> feedList = null;
private ProgressBar progressbar = null;
private ListView feedListView = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.list_row_layout, container, false);
progressbar = (ProgressBar)rootView.findViewById(R.id.progressBar);
String url = "";
new DownloadFilesTask().execute(url);
return rootView;
}
public void updateList() {
feedListView= (ListView)getActivity().findViewById(R.id.custom_list);
feedListView.setVisibility(View.VISIBLE);
progressbar.setVisibility(View.GONE);
**feedListView.setAdapter(new CustomListAdapter(this, feedList));**
feedListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
Object o = feedListView.getItemAtPosition(position);
FeedItem newsData = (FeedItem) o;
**Intent intent = new Intent(FeedListActivity.this, FeedDetailsActivity.class);**
intent.putExtra("feed", newsData);
startActivity(intent);
}
});
}
public class DownloadFilesTask extends AsyncTask<String, Integer, Void> {
@Override
protected void onProgressUpdate(Integer... values) {
}
@Override
protected void onPostExecute(Void result) {
if (null != feedList) {
updateList();
}
}
@Override
protected Void doInBackground(String... params) {
String url = params[0];
// getting JSON string from URL
JSONObject json = getJSONFromUrl(url);
//parsing json data
parseJson(json);
return null;
}
}
public JSONObject getJSONFromUrl(String url) {
InputStream is = null;
JSONObject jObj = null;
String json = null;
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
public void parseJson(JSONObject json) {
try {
// parsing json object
if (json.getString("status").equalsIgnoreCase("ok")) {
JSONArray posts = json.getJSONArray("posts");
feedList = new ArrayList<FeedItem>();
for (int i = 0; i < posts.length(); i++) {
JSONObject post = (JSONObject) posts.getJSONObject(i);
FeedItem item = new FeedItem();
item.setTitle(post.getString("title"));
item.setDate(post.getString("description"));
item.setId(post.getString("id"));
item.setUrl(post.getString("url"));
item.setContent(post.getString("description"));
JSONArray attachments = post.getJSONArray("attachments");
if (null != attachments && attachments.length() > 0) {
JSONObject attachment = attachments.getJSONObject(0);
if (attachment != null)
item.setAttachmentUrl(attachment.getString("url"));
}
feedList.add(item);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Problems are on this lines
feedListView.setAdapter(new CustomListAdapter(this, feedList));
Intent intent = new Intent(FeedListActivity.this, FeedDetailsActivity.class);
Multiple markers at this line - Line breakpoint:Fragment1 [line: 57] - updateList()
- The constructor CustomListAdapter(Fragment1, ArrayList<FeedItem>) is
undefined
No enclosing instance of the type FeedListActivity is accessible in scope
CustomListAdapter:
public class CustomListAdapter extends BaseAdapter {
private ArrayList<FeedItem> listData;
private LayoutInflater layoutInflater;
private Context mContext;
public CustomListAdapter(Context context, ArrayList<FeedItem> listData) {
this.listData = listData;
layoutInflater = LayoutInflater.from(context);
mContext = context;
}
@Override
public int getCount() {
return listData.size();
}
@Override
public Object getItem(int position) {
return listData.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.list_row_layout, null);
holder = new ViewHolder();
holder.headlineView = (TextView) convertView.findViewById(R.id.title);
holder.reportedDateView = (TextView) convertView.findViewById(R.id.date);
holder.imageView = (ImageView) convertView.findViewById(R.id.thumbImage);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
FeedItem newsItem = (FeedItem) listData.get(position);
holder.headlineView.setText(newsItem.getTitle());
holder.reportedDateView.setText(newsItem.getDate());
if (holder.imageView != null) {
new ImageDownloaderTask(holder.imageView).execute(newsItem.getAttachmentUrl());
}
return convertView;
}
static class ViewHolder {
TextView headlineView;
TextView reportedDateView;
ImageView imageView;
}
}
解决方案
in this line feedListView.setAdapter(new CustomListAdapter(this, feedList)); just replace this with getActivity();
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