Android的 - 移植ListView与JSONArray数据 [英] android - populating ListView with data from JSONArray
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问题描述
情况：我是从服务器获取一个的JSONObject 包含用户的播放列表。我想显示在的ListView 这个数据，也有我的测试情况下，288的音频文件。该JSON是正确分析，大小等于288.我创建了一个帮助类，并与它的对象参数化的的ArrayList 。问题：有是正好288项在我的的ListView 但正确的条目艺术家 - 标题上去指数13（不知道为什么），然后他们得到的重复的。所以，我没有在列表中288不同的条目，但我只有14如此反复，直到列表的末尾项。
更新：我删除if语句，它解决了这个问题，但RAM的消费却增加了3MB。优化有什么建议？
公共类AudioList扩展ListActivity {私人的ListView LV;
私人的JSONObject usersPlaylist，singleJSONItem;
私人JSONArray responseJSONArray;
私人共享preferences preFS;
私人PlaylistItem audioList;@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_audio_list）;
在里面（）; ArrayList的＆LT; PlaylistItem＆GT;播放列表=新的ArrayList＆LT; PlaylistItem＆GT;（）;
尝试{
usersPlaylist = Utils.retrieveJsonObjectFromUrl（新URL（
APP_CONSTANTS.REQUEST_AUDIO_LIST（preFS）），这一点）;
responseJSONArray = usersPlaylist.getJSONArray（回应）; 的for（int i = 0; I＆LT; responseJSONArray.length（）;我++）{
singleJSONItem = responseJSONArray.getJSONObject（ⅰ）;
audioList =新PlaylistItem（singleJSONItem）;
playlist.add（audioList）;
} Toast.makeText（getApplicationContext（），
Integer.toString（playlist.size（）），Toast.LENGTH_LONG）
。显示（）; //有288项，JSONArray正确解析 }赶上（MalformedURLException的E）{ e.printStackTrace（）;
}赶上（JSONException E）{ e.printStackTrace（）;
}赶上（IOException异常五）{ e.printStackTrace（）;
} AudioListAdapter适配器=新AudioListAdapter（这一点，
R.layout.playlist_item，播放列表）;
lv.setAdapter（适配器）;}私人无效的init（）{
LV = getListView（）;
lv.setTranscriptMode（00000000）;
lv.setDividerHeight（1）;
lv.setSmoothScrollbarEnabled（真）;
preFS = preferenceManager.getDefaultShared preferences（本）;}
该PlayListItem类：
公共类PlaylistItem {私人字符串艺术家，标题;
私人的JSONObject OBJ;公共PlaylistItem（OBJ的JSONObject）{
this.obj = OBJ;
}
公共PlaylistItem（）{}公共字符串getArtist（）{
尝试{
艺术家= obj.getString（艺术家）;
}赶上（JSONException E）{ e.printStackTrace（）;
}
返回的艺术家;}公共字符串的getTitle（）{
尝试{
标题= obj.getString（标题）;
}赶上（JSONException E）{ e.printStackTrace（）;
}
返回称号;
}
}
适配器：
公共类AudioListAdapter扩展ArrayAdapter＆LT; PlaylistItem＆GT; {私人上下文的背景下;
私人诠释layoutResourceId;
私人PlaylistItem澳元;
私人的ArrayList＆LT; PlaylistItem＆GT;数据= NULL;公共AudioListAdapter（上下文的背景下，INT layoutResourceId，
ArrayList的＆LT; PlaylistItem＆GT;数据）{
超级（上下文，layoutResourceId，数据）;
this.layoutResourceId = layoutResourceId;
this.context =背景;
this.data =数据;}@覆盖
公共查看getView（INT位置，查看convertView，父母的ViewGroup）{
查看排= convertView;
ViewHolder持有人=新ViewHolder（）;
AUD = data.get（位置）;
//它给一个正确的位置上，如果我硬code中的指数，像data.get（99）;
如果（行== NULL）{ LayoutInflater充气=（（活动）上下文）.getLayoutInflater（）;
行= inflater.inflate（layoutResourceId，父母，假）;
holder.play =（按钮）row.findViewById（R.id.btn_list_play）;
holder.imgSaved =（ImageView的）行
.findViewById（R.id.img_list_audio_saved）;
holder.tvArtist =（TextView中）一行
.findViewById（R.id.tvListItemArtist）;
holder.tvTitle =（TextView中）row.findViewById（R.id.tvListItemSong）; holder.tvArtist.setText（aud.getArtist（））;
holder.tvTitle.setText（aud.getTitle（））; } 返回行;
}静态类ViewHolder {
按钮播放;
ImageView的imgSaved;
TextView的tvArtist，tvTitle;} }
解决方案
我已经在你的getView method.Replace做了一些修改，并检查它。
@覆盖
公共查看getView（INT位置，查看convertView，父母的ViewGroup）{
查看排= convertView;
ViewHolder持有人;
AUD = data.get（位置）;
//它给一个正确的位置上，如果我硬code中的指数，像data.get（99）;
如果（行== NULL）{
持有人=新ViewHolder（）;
LayoutInflater充气=（（活动）上下文）.getLayoutInflater（）;
行= inflater.inflate（layoutResourceId，父母，假）;
holder.play =（按钮）row.findViewById（R.id.btn_list_play）;
holder.imgSaved =（ImageView的）row.findViewById（R.id.img_list_audio_saved）;
holder.tvArtist =（TextView中）一行.findViewById（R.id.tvListItemArtist）;
holder.tvTitle =（TextView中）row.findViewById（R.id.tvListItemSong）;
row.setTag（保持器）;
}
其他
{
支架=（ViewHolder）row.getTag（）; }
holder.tvArtist.setText（aud.getArtist（））;
holder.tvTitle.setText（aud.getTitle（））; 返回行;
}
Situation: I'm getting a JSONObject containing user's playlist from the server. I want to display this data in a ListView, there are 288 audio files in my test case. The JSON is parsed correctly, the size equals to 288. I created a help class and parametrized the ArrayList with its Objects. The problem: there're exactly 288 items in my ListView BUT the correct entries Artist - Title go up to index 13 (don't know why) and then they get repeated. So I don't have 288 different entries in the List, but I have only 14 entries which are repeated until the end of the List.
UPDATE: I removed the if statement and it solved the issue but RAM consumption has increased by 3MB. Any suggestions for optimizing?
public class AudioList extends ListActivity {
private ListView lv;
private JSONObject usersPlaylist, singleJSONItem;
private JSONArray responseJSONArray;
private SharedPreferences prefs;
private PlaylistItem audioList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_audio_list);
init();
ArrayList<PlaylistItem> playlist = new ArrayList<PlaylistItem>();
try {
usersPlaylist = Utils.retrieveJsonObjectFromUrl(new URL(
APP_CONSTANTS.REQUEST_AUDIO_LIST(prefs)), this);
responseJSONArray = usersPlaylist.getJSONArray("response");
for (int i = 0; i < responseJSONArray.length(); i++) {
singleJSONItem = responseJSONArray.getJSONObject(i);
audioList = new PlaylistItem(singleJSONItem);
playlist.add(audioList);
}
Toast.makeText(getApplicationContext(),
Integer.toString(playlist.size()), Toast.LENGTH_LONG)
.show(); //there are 288 entries, JSONArray parsed correctly
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
AudioListAdapter adapter = new AudioListAdapter(this,
R.layout.playlist_item, playlist);
lv.setAdapter(adapter);
}
private void init() {
lv = getListView();
lv.setTranscriptMode(0x00000000);
lv.setDividerHeight(1);
lv.setSmoothScrollbarEnabled(true);
prefs = PreferenceManager.getDefaultSharedPreferences(this);
}
The PlayListItem class:
public class PlaylistItem {
private String artist, title;
private JSONObject obj;
public PlaylistItem(JSONObject obj) {
this.obj = obj;
}
public PlaylistItem(){
}
public String getArtist() {
try {
artist = obj.getString("artist");
} catch (JSONException e) {
e.printStackTrace();
}
return artist;
}
public String getTitle() {
try {
title = obj.getString("title");
} catch (JSONException e) {
e.printStackTrace();
}
return title;
}
}
The adapter:
public class AudioListAdapter extends ArrayAdapter<PlaylistItem> {
private Context context;
private int layoutResourceId;
private PlaylistItem aud;
private ArrayList<PlaylistItem> data = null;
public AudioListAdapter(Context context, int layoutResourceId,
ArrayList<PlaylistItem> data) {
super(context, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.context = context;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ViewHolder holder = new ViewHolder();
aud = data.get(position);
//it's giving a CORRECT position if I hardcode the index, like data.get(99);
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder.play = (Button) row.findViewById(R.id.btn_list_play);
holder.imgSaved = (ImageView) row
.findViewById(R.id.img_list_audio_saved);
holder.tvArtist = (TextView) row
.findViewById(R.id.tvListItemArtist);
holder.tvTitle = (TextView) row.findViewById(R.id.tvListItemSong);
holder.tvArtist.setText(aud.getArtist());
holder.tvTitle.setText(aud.getTitle());
}
return row;
}
static class ViewHolder {
Button play;
ImageView imgSaved;
TextView tvArtist, tvTitle;
}
}
解决方案
I have done some modifications in your getView method.Replace it and check it.
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ViewHolder holder;
aud = data.get(position);
//it's giving a CORRECT position if I hardcode the index, like data.get(99);
if (row == null) {
holder = new ViewHolder();
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder.play = (Button) row.findViewById(R.id.btn_list_play);
holder.imgSaved = (ImageView) row.findViewById(R.id.img_list_audio_saved);
holder.tvArtist = (TextView) row .findViewById(R.id.tvListItemArtist);
holder.tvTitle = (TextView) row.findViewById(R.id.tvListItemSong);
row.setTag(holder);
}
else
{
holder = (ViewHolder ) row.getTag();
}
holder.tvArtist.setText(aud.getArtist());
holder.tvTitle.setText(aud.getTitle());
return row;
}
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