Question

我在ListView中正确识别项目时遇到了一些麻烦。

有4个类很重要，这是很多代码所以最初我将解释这些类的逻辑。

输入ListActivity并初始化其ListView
执行从服务器下载JSON响应的AsyncTask，解析它，使用Objects填充ListView并在显示ProgressDialog时设置适配器
PlaylistItem 类包含只从单个JSONObject获取数据的方法。它用于参数化ArrayList及其对象
- 在AsyncTask完成后，列表中的项目显示为| Button |艺术家（TextView） - 标题（TextView）

更新

解决了第一个问题，但仍然无法弄清楚按钮的问题

2）。我在Adapter的getView（）方法中为我的按钮设置了OnClickListener。为了确定按钮是否被正确识别，我什么也没做，只是改变了它的背景。但是单击某个按钮会强制更改每个第11或第12个按钮的背景。到目前为止无法弄明白。

在这些问题得到解决之前，我无法继续获取网址和流媒体音频，因此非常感谢任何帮助。我的课程如下，请询问是否有不清楚的事情。

AudioList

         public class AudioList extends ListActivity {
private ListView lv;
private PlaylistLoader loader;
private AudioListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_audio_list);
    init(); // initialize the ListView

    /*--- populate the list with user's audio in case network connection is available ---*/
    loader = new PlaylistLoader(this, lv, adapter);
    if (Utils.isNetworkAvailable(this)) {
        loader.execute();
    } else {
        APP_CONSTANTS.NO_DATA_CONNECTION(this);
    }

}

@Override
protected void onResume() {
    super.onResume();
    lv.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {

            Toast.makeText(getApplicationContext(), Integer.toString(arg2),
                    Toast.LENGTH_SHORT).show();
            }
    });

}

private void init() {
    lv = getListView();
    lv.setTranscriptMode(0x00000000);
    lv.setDividerHeight(1);
    lv.setSmoothScrollbarEnabled(true);
    lv.setVerticalFadingEdgeEnabled(true);

}

PlaylistLoader

      public class PlaylistLoader extends AsyncTask<Void, Void, Void> {

private JSONObject usersPlaylist, singleJSONItem;
private JSONArray responseJSONArray;
private ListView lv;
private ArrayList<PlaylistItem> playlist;
private Activity a;
private PlaylistItem audioList;
private SharedPreferences prefs;
private ProgressDialog pd;
AudioListAdapter adapter;

public PlaylistLoader(Activity a, ListView lv, AudioListAdapter adapter) {
    this.lv = lv;
    this.a = a;
    this.adapter = adapter;
}

@Override
protected Void doInBackground(Void... arg0) {
    /*--- create new ArrayList of PlaylistItem Objects ---*/
    playlist = new ArrayList<PlaylistItem>();
    /*--- get the preferences using context of calling activity ---*/
    prefs = PreferenceManager.getDefaultSharedPreferences(a);
    try {
        /*--- download the response JSONObject from server // access_token and 
         * user_id come from activity's defaultSharedPreferences ---*/
        usersPlaylist = Utils.retrieveJsonObjectFromUrl(new URL(
                APP_CONSTANTS.REQUEST_AUDIO_LIST(prefs)), a);
        /*--- get the response array from received object ---*/
        responseJSONArray = usersPlaylist.getJSONArray("response");
        /*--- populate the ArrayList with Objects from the response array ---*/
        for (int i = 0; i < responseJSONArray.length(); i++) {
            singleJSONItem = responseJSONArray.getJSONObject(i);
            audioList = new PlaylistItem(singleJSONItem);
            playlist.add(audioList);

        }

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    pd = new ProgressDialog(a);
    pd.setTitle("Please wait");
    pd.setMessage("Retrieving audio list...");
    pd.show();

}

@Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);
    lv.setVisibility(View.VISIBLE);
    pd.dismiss();
    /*--- set the adapter passed in constructor as an adapter for passed ListView ---*/
    adapter = new AudioListAdapter(a, R.layout.playlist_item, playlist);
    lv.setAdapter(adapter);

}
    }

AudioListAdapter

           public class AudioListAdapter extends ArrayAdapter<PlaylistItem> {
private PlaylistItem pl;
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 PlaylistItem getItem(int position) {
    return super.getItem(position);
}

@Override
public int getCount() {
    return data.size();
}

@Override
public int getPosition(PlaylistItem item) {
    return super.getPosition(item);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    pl = new PlaylistItem();
    aud = getItem(position);

    if (convertView == null) {
        LayoutInflater inflater = ((Activity) context).getLayoutInflater();
        convertView = inflater.inflate(layoutResourceId, parent, false);
        pl.btnPlay = (Button) convertView.findViewById(R.id.btn_list_play);
        pl.imgSaved = (ImageView) convertView
                .findViewById(R.id.img_list_audio_saved);
        pl.tvArtist = (TextView) convertView
                .findViewById(R.id.tvListItemArtist);
        pl.tvTitle = (TextView) convertView
                .findViewById(R.id.tvListItemSong);

        convertView.setTag(pl);
    } else {
        pl = (PlaylistItem) convertView.getTag();
        pl.btnPlay.setBackgroundResource(R.drawable.list_button_play);
    }

    pl.tvArtist.setText(aud.getArtist() + " " + "-");
    pl.tvTitle.setText(aud.getTitle());

    pl.btnPlay.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            /*--- vibrate if this option is enabled in the preferences ---*/
            if (APP_CONSTANTS.isHapticFeedbackEnabled(getContext())) {
                APP_CONSTANTS.doVibrate(getContext());

            }
         pl.btnPlay.setBackgroundResource(R.drawable.list_button_pause);

        }
    });

    return convertView;
}

PlayListItem

     public class PlaylistItem {

private String artist, title;
private JSONObject obj;
public Button btnPlay;
public TextView tvArtist, tvTitle;
public ImageView imgSaved;
public int duration;
public int audio_id;
public String url;

/*--- the constructor takes a single JSONObject from the response array ---*/
public PlaylistItem(JSONObject obj) {
    this.obj = obj;
}

public PlaylistItem() {
    // default constructor
}

/*--- the methods below return values by key from the passed JSONObject ---*/

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;
}

public int getID() {
    try {
        audio_id = obj.getInt("aid");
    } catch (JSONException e) {

        e.printStackTrace();
    }
    return audio_id;
}

public String getURL() {
    try {
        url = obj.getString("url");
    } catch (JSONException e) {

        e.printStackTrace();
    }
    return url;
}
    }

Answer 1

修改：

试试这个

在drawable中选择一个自定义选择器 button_play.xml

<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@drawable/pause_button" android:state_selected="true" /> <item android:drawable="@drawable/play_button" /> </selector>

像这样修改你的适配器

public class AudioListAdapter extends ArrayAdapter<PlaylistItem> { private PlaylistItem pl; private Context context; private int layoutResourceId; private PlaylistItem aud; private ArrayList<PlaylistItem> data = null; Button previous; public AudioListAdapter(Context context, int layoutResourceId, ArrayList<PlaylistItem> data) { super(context, layoutResourceId, data); this.layoutResourceId = layoutResourceId; previous=new Button(context); this.context = context; this.data = data; } .... .... @Override public View getView(int position, View convertView, ViewGroup parent) { pl = new PlaylistItem(); aud = getItem(position); if (convertView == null) { LayoutInflater inflater = ((Activity) context).getLayoutInflater(); convertView = inflater.inflate(layoutResourceId, parent, false); pl.btnPlay = (Button) convertView.findViewById(R.id.btn_list_play); pl.btnPlay.setBackGroundResouce(R.drawable.button_play); //you can set here or in xml pl.imgSaved = (ImageView) convertView .findViewById(R.id.img_list_audio_saved); pl.tvArtist = (TextView) convertView .findViewById(R.id.tvListItemArtist); pl.tvTitle = (TextView) convertView .findViewById(R.id.tvListItemSong); convertView.setTag(pl); } else { pl = (PlaylistItem) convertView.getTag(); } pl.tvArtist.setText(aud.getArtist() + " " + "-"); pl.tvTitle.setText(aud.getTitle()); pl.btnPlay.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { /*--- vibrate if this option is enabled in the preferences ---*/ if (APP_CONSTANTS.isHapticFeedbackEnabled(getContext())) { APP_CONSTANTS.doVibrate(getContext()); } //for some reason, the background gets changed for every 11th or 12th button in the list Button current=((Button)v); current.setSelected(true); previous.setSelected(false); previous=current; } }); return convertView; } }

您的按钮和列表项不可点击的原因是您的列表有焦点项按钮，因此您需要为按钮设置setFocusable = false。尝试为xml中的按钮设置focusable = false。如果它不适合你，那么

在你的行xml文件
中
1.set focusable = true为您的按钮。 2.在父项目的同一组android:descendantFocusability="blocksDescendants"中（即您的视图所在的父布局）。

在为按钮设置onclickListener之后的getView（）方法中，为按钮设置focusable false。它肯定会起作用。我希望这会对你有帮助..

Answer 2

但是单击某个按钮会强制更改每个第11或第12个按钮的背景。到目前为止无法弄明白。

您正在与ListViews回收行布局的方式作斗争可以这样想：如果你有一个包含10,000行的ListView但在屏幕上只能容纳其中的9行，那么创建10,000个独特的布局就没有意义了。这只是浪费资源，而ListView只创建~10个布局并重用它们。

解决方案：重复使用时，将每一行返回到其默认状态。在getView()添加：

} else {
    pl = (PlaylistItem) convertView.getTag();
    pl.btnPlay.setBackgroundResource(R.drawable.list_button_play);
    // I guessed at the resource's name         ^^^^^^^^^^^^^^^^
}

（你也可以做一些小改动来加速你的代码。例如，你只需要一个OnClickListener，因为它们都包含相同的代码，使它成为一个类变量并将其传递给每个播放按钮。还有更多。）

android - 识别ListView中的项目

2 个答案: