我试图制作歌曲列表。每个列表项应包含标题，艺术家，歌曲开始的时间和一些专辑封面。 我似乎无法让它正常工作，每次我尝试它只会将最后一个条目中的数据加载到所有行中。 我已经阅读了有关ViewHolders和图片加载库的内容，并试图实现我发现的没有运气的东西。
这是我的代码：
public class MyAdapter extends SimpleAdapter {
private static LayoutInflater inflater = null;
List data;
public MyAdapter(Context context, List<? extends Map<String, ?>> data,
int resource, String[] from, int[] to) {
super(context, data, resource, from, to);
this.data = data;
inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View vi = convertView;
String imgURL = SongListFragment.imgURL;
if(convertView == null){
vi = inflater.inflate(R.layout.custom_listitem, null);
TextView title = (TextView) vi.findViewById(R.id.title);
TextView artist = (TextView) vi.findViewById(R.id.artist);
TextView timeInfo = (TextView) vi.findViewById(R.id.timeInfo);
title.setText(SongListFragment.title);
artist.setText(SongListFragment.artist);
timeInfo.setText(SongListFragment.starttime);
Picasso.with(vi.getContext()).load(imgURL).into((ImageView)vi.findViewById(R.id.img));
Log.d("Image", imgURL);
}
return vi;
}
}
public class HttpGetTask extends AsyncTask<String, Void, String> {
interface OnHttpGetListener{
public void httpGetCompleted(String response);
public void httpGetFailed(String error);
}
private OnHttpGetListener mListener;
private boolean mGetFailed;
private AndroidHttpClient client;
public HttpGetTask(OnHttpGetListener listener) {
mListener = listener;
client = AndroidHttpClient.newInstance("Android");
}
@Override
protected String doInBackground(String... params) {
try {
HttpGet uri = new HttpGet(params[0]);
HttpResponse resp = client.execute(uri);
ByteArrayOutputStream out = new ByteArrayOutputStream();
resp.getEntity().writeTo(out);
resp.getEntity().consumeContent();
out.close();
client.close();
return out.toString();
} catch (Exception e) {
mGetFailed = true;
e.printStackTrace();
return e.getMessage();
}
}
@Override
protected void onPostExecute(String response) {
if(mGetFailed) {
mListener.httpGetFailed(response);
} else {
mListener.httpGetCompleted(response);
}
}
}
public class SongListFragment extends Fragment implements OnHttpGetListener {
ListView listview;
ArrayList<HashMap<String, String>> listEntries = new ArrayList<HashMap<String, String>>();
static String imgURL = null;
static String title = null;
static String artist = null;
static String starttime = null;
static String endtime = null;
public SongListFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.listview_fragment, container, false);
listview = (ListView) rootView.findViewById(R.id.songlist);
getJSON();
return rootView;
}
private void getJSON(){
HttpGetTask jsonGetter = new HttpGetTask(this); //registers to listen callbacks
final String jsonUrl = "http://stark-castle-5854.herokuapp.com/songlist"; //url to json
jsonGetter.execute(jsonUrl); //starts the async task
}
public void httpGetCompleted(String response) {
// this gets called when the background task
// to get json is completed without errors
try {
JSONArray newJArray = new JSONArray(response);
for(int i = 0; i < newJArray.length(); i++){
JSONObject json = newJArray.getJSONObject(i);
title = json.getString("title");
artist = json.getString("artist");
starttime = json.getString("starttimeutc");
endtime = json.getString("stoptimeutc");
//all entries do not have an img resource
if(json.has("img")){
imgURL = json.getString("img");
}else{
imgURL = null;
}
long sTime = Long.parseLong(starttime);
Date date = new Date(sTime);
SimpleDateFormat sdf = new SimpleDateFormat("E MMM dd, HH:mm:ss");
sdf.setTimeZone(TimeZone.getTimeZone("GMT+1"));
String formattedDate = sdf.format(date);
Log.d("test", "Time: " + date);
//hashmap to store values for the listview in
HashMap<String, String> map = new HashMap<String, String>();
map.put("Title", title);
map.put("Artist", artist);
map.put("Start", "Starts: " + formattedDate);
map.put("End", endtime);
map.put("ImgURL", imgURL);
//add hashmap values to arraylist
listEntries.add(map);
Log.d("test", "Success! Artist: " + artist +
" Title: " + title +
" Start: " + starttime +
" End: " + endtime +
" ImgURL: " + imgURL);
}
//add arraylist to listview
ListAdapter adapter = new MyAdapter(getActivity(), listEntries,
R.layout.custom_listitem,
new String[] { "Title", "Artist", "Start"}, new int[] {
R.id.title, R.id.artist, R.id.timeInfo});
listview.setAdapter(adapter);
//Picasso.with(getActivity()).load("http://java.sogeti.nl/JavaBlog/wp-content/uploads/2009/04/android_icon_256.png").into((ImageView)getView().findViewById(R.id.img));
} catch (JSONException e) {
e.printStackTrace();
}
}
public void httpGetFailed(String error) {
// this gets called when the background task fails to get json
Log.e("GetFail", error); // printing to error
}
}
请帮我StackOverflow，你是我唯一的希望。
答案 0 :(得分：1)
在片段中，您将数据保存在静态变量中。在这种情况下，执行for循环后，最后的条目将保存在所有这些静态变量中。因此，只有一个条目是最后一个存储的。在getview视图中，您每次都在访问这些变量，这意味着您要访问所有行的相同值。
要解决此问题，您需要访问作为列表（地图）传递的数据。对此进行调用并将其存储为对象。然后获取这些对象的属性。
适配器getview()
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View vi = convertView;
String imgURL = SongListFragment.imgURL;
if(convertView == null){
vi = inflater.inflate(R.layout.custom_listitem, null);
TextView title = (TextView) vi.findViewById(R.id.title);
TextView artist = (TextView) vi.findViewById(R.id.artist);
TextView timeInfo = (TextView) vi.findViewById(R.id.timeInfo);
// NOTE THAT THIS PSEUDO CODE YOU NEED TO GET THE LIST POSITION AND MAP POSITION HERE TO ACCESS TITLE<ARTIST AND STARTTIME.
title.setText(data.get(position).title);
artist.setText(data.get(position).artist);
timeInfo.setText(data.get(position).starttime);
Picasso.with(vi.getContext()).load(imgURL).into((ImageView)vi.findViewById(R.id.img));
Log.d("Image", imgURL);
}
return vi;
}
另外我建议你在getView()中使用ViewHolder模式，这是在Listview中扩充数据的标准方法。
更新：
title.setText(data.get(position).get("Title"));
artist.setText(data.get(position).get("Artist"));
timeInfo.setText(data.get(position).get("Start"));
上面的内容可以帮助您从散列图列表中获取数据。
希望你明白并希望这会有所帮助。