Question

我有一个音乐播放器应用程序，应该打开并显示手机/ SD卡上的曲目列表，但是当我启动应用程序时它没有显示任何内容..

我遵循了一个教程，所以我不完全清楚一切应该做什么。特别是使用xml ListView：http://www.androidhive.info/2012/03/android-building-audio-player-tutorial/

以下是我的java类，它们应该对可能导致此问题的重要性：

Library.java

public class Library extends ListActivity {
// Songs list
public ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.library);

    ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();

    TrackManager plm = new TrackManager();
    // get all songs from sdcard
    this.songsList = plm.getPlayList();

    // looping through playlist
    for (int i = 0; i < songsList.size(); i++) {
        // creating new HashMap
        HashMap<String, String> song = songsList.get(i);

        // adding HashList to ArrayList
        songsListData.add(song);
    }

    // Adding menuItems to ListView
    ListAdapter adapter = new SimpleAdapter(this, songsListData, R.layout.libraryitem, new String[] { "songTitle" }, new int[] { R.id.songTitle });

    setListAdapter(adapter);

    // selecting single ListView item
    ListView lv = getListView();
    // listening to single listitem click
    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // getting listitem index
            int songIndex = position;

            // Starting new intent
            Intent in = new Intent(getApplicationContext(), Player.class);
            // Sending songIndex to PlayerActivity
            in.putExtra("songIndex", songIndex);
            setResult(100, in);
            // Closing PlayListView
            finish();
        }
    });
}

TrackManager.java

public class TrackManager {
// SDCard Path
final String MEDIA_PATH = new String(Environment.getExternalStorageDirectory().getPath());
private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

// Constructor
public TrackManager() {

}

// Function to read all mp3 files from sdcard and store the details in
// ArrayList

public ArrayList<HashMap<String, String>> getPlayList() {
    File home = new File(MEDIA_PATH);
    if (home.listFiles(new FileExtensionFilter()).length > 0) {
        for (File file : home.listFiles(new FileExtensionFilter())) {
            HashMap<String, String> song = new HashMap<String, String>();
            song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
            song.put("songPath", file.getPath());

            // Adding each song to SongList
            songsList.add(song);
        }
    }
    // return songs list array
    return songsList;
}

// Class to filter files which are having .mp3 extension

class FileExtensionFilter implements FilenameFilter {
    public boolean accept(File dir, String name) {
        return (name.endsWith(".mp3") || name.endsWith(".MP3"));
    }
}
}

我有一些xml布局显示了这些类应该填充的列表视图，但我只是得到一个空白的空列表，就像那里什么都没有：

Library activity

更新

library.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#111111"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".Library" >


<TextView
    android:id="@+id/tvTracks"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/tracks"
    android:textSize="20sp" />

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_below="@+id/tvTracks"
    android:divider="#999999"
    android:dividerHeight="1dp"
    android:listSelector="@drawable/list_selector" />

</RelativeLayout>

ListView的libraryitem.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/list_selector"
android:orientation="vertical"
android:padding="5dp"
tools:ignore="SelectableText" >

<TextView
    android:id="@+id/songTitle"
    android:text="@string/title"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="5dp"
    android:textSize="15sp" />

</RelativeLayout>

希望有人能解决我的问题..

Answer 1

我曾经将MediaStore用于我在谷歌播放的音乐应用程序，它似乎更有效地抓取设备上的所有音频文件。这里我为你抓取所有的音频文件：

public ArrayList<HashMap<String, String>> getPlayList(Context c) {



    /*use content provider to get beginning of database query that queries for all audio by display name, path
    and mimtype which i dont use but got it incase you want to scan for mp3 files only you can compare with RFC  mimetype for mp3's
    */
    final Cursor mCursor = c.getContentResolver().query(
            MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
            new String[] { MediaStore.Audio.Media.DISPLAY_NAME, MediaStore.Audio.Media.DATA,MediaStore.Audio.Media.MIME_TYPE }, null, null,
            "LOWER(" + MediaStore.Audio.Media.TITLE + ") ASC");

    String songs_name = "";
    String mAudioPath = "";

    /* run through all the columns we got back and save the data we need into the arraylist for our listview*/
    if (mCursor.moveToFirst()) {
        do {

        String file_type = mCursor.getString(mCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.MIME_TYPE));


            songs_name = mCursor.getString(mCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME));
            mAudioPath = mCursor.getString(mCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA));
            HashMap<String, String> song = new HashMap<String, String>();

            song.put("songTitle", songs_name);
            song.put("songPath", mAudioPath);

            songsList.add(song);

        } while (mCursor.moveToNext());
    }   

    mCursor.close(); //cursor has been consumed so close it
return songsList;
}

在您的代码中调用它来传递上下文：

this.songsList = plm.getPlayList(this);

我认为这是可接受的方式，如果它可以帮助你，你可以接受这个答案。

音乐播放器库ListView填充问题

1 个答案: