如何获取播放列表列表并在listView中显示它

问题描述

我正在尝试从sdcard获取播放列表列表并将其显示在listView中。但我无法取得结果。 listView显示为空。



我使用的代码如下。



SongManager.java

I'm trying to get list of playlist from sdcard and display it in a listView. but i'm not being able to fetch the result. the listView shows empty.

the code i used is as follows.

SongManager.java

final String MEDIA_PATH = new String("/mnt/sdcard/");
    private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
    private String mp3Pattern = ".mp3";

    // Constructor
    public SongsManager() {

    }

    /**
     * Function to read all mp3 files 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"));
        }
    }

MainActivity.java

MainActivity.java

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

        SongsManager plm = new SongsManager();
        // 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.playlist_item, new String[] { "songTitle" }, new int[] {
                R.id.songTitle });

        setListAdapter(adapter);

        // selecting single ListView item
        ListView lv = getListView();

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