Displaying list of music files in External SD Card in a ListView

Question

I want to show the list of music files available in SD card in my app. Here is the java code. Code is working without any error but no MP3 Files are shown instead ListView is being populated with the Names of folders in phone's internal memory.

MainActivity.java

final String MEDIA_PATH = Environment.getExternalStorageDirectory().getAbsolutePath();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        ListView listsong =(ListView)findViewById(R.id.songslistView);

        ArrayList<String> mp3list = new ArrayList<String>();
        mp3list=mp3select();
        Toast.makeText(this, "mp3files" + mp3list,                Toast.LENGTH_LONG).show();

        ArrayAdapter<String> listAdapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,mp3list);
        listsong.setAdapter(listAdapter);

    }

    public ArrayList<String> mp3select(){
        File home = new File(MEDIA_PATH);
        ArrayList<String> list = new ArrayList<String>();
        //if (home.isDirectory())

        if (home.listFiles(new AudioFileFilter()).length > 0)
        {
            for (File file : home.listFiles(new AudioFileFilter()))
            {
                list.add(file.getName());
            }
        }
        return list;
    }

AudioFileFilter.java

public class AudioFileFilter implements FileFilter {

    protected static final String TAG = "AudioFileFilter";
    /**
     * allows Directories
     */
    private final boolean allowDirectories;

    public AudioFileFilter( boolean allowDirectories) {
        this.allowDirectories = allowDirectories;
    }

    public AudioFileFilter() {
        this(true);
    }

    @Override
    public boolean accept(File f) {
        if ( f.isHidden() || !f.canRead() ) {
            return false;
        }

        if ( f.isDirectory() ) {
            return allowDirectories;
        }
        String ext = getFileExtension(f);
        if ( ext == null) return false;
        try {
            if ( SupportedFileFormat.valueOf(ext.toUpperCase()) != null ) {
                return true;
            }
        } catch(IllegalArgumentException e) {
            //Not known enum value
            return false;
        }
        return false;
    }

    public String getFileExtension( File f ) {
        int i = f.getName().lastIndexOf('.');
        if (i > 0) {
            return f.getName().substring(i+1);
        } else
            return null;
    }

    /**
     * Files formats currently supported by Library
     */
    public enum SupportedFileFormat
    {
        _3GP("3gp"),
        MP4("mp4"),
        M4A("m4a"),
        AAC("aac"),
        TS("ts"),
        FLAC("flac"),
        MP3("mp3"),
        MID("mid"),
        XMF("xmf"),
        MXMF("mxmf"),
        RTTTL("rtttl"),
        RTX("rtx"),
        OTA("ota"),
        IMY("imy"),
        OGG("ogg"),
        MKV("mkv"),
        WAV("wav");

        private String filesuffix;

        SupportedFileFormat( String filesuffix ) {
            this.filesuffix = filesuffix;
        }

        public String getFilesuffix() {
            return filesuffix;
        }
    }

}

I have gone through few questions related to the topic. I am not able to identify the problem. Any help is appreciated. Thanks in Advance.

Answer 1

You aren't recursing through the directories, instead you're just showing the directory names if you've passed in allowDirectories to your AudioFilter, which you have since you are passing in a no argument constructor which defaults to true. What you want to do scan a directory for files matching your filter, and when you find a subdirectory, you want to add that to a list of directories to scan. You can do this a number of ways. One way is recursion. When you find a directory you call the same function with that directory as the input parameter. Another way is you could keep a list of directories to scan and each time you find a directory, append that to the list. When you are done scanning files in a directory, pop a directory off the list of directories and continue until you've got no directories to scan.

Here is the idea for the recursive way:

 private FileFilter mFileFilter;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    mFileFilter = new AudioFilter();

    ListView listsong =(ListView)findViewById(R.id.songslistView);

    ArrayList<String> mp3list = new ArrayList<String>();
    ArrayList<File> fileList = new ArrayList<File>();
    File home = new File(MEDIA_PATH);
    mp3select(home, fileList);
    //now you need to map your ArrayList<File> to ArrayList<String>.  Personally I would use a different kind of adapter and just return the name of the file while keeping the entire file reference


    ArrayAdapter<String> listAdapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,mp3list);
    listsong.setAdapter(listAdapter);

}

public void mp3select(File dir, ArrayList<File> fileList){  
    if (!home.isDirectory()) {
        return;
    }
    for (File file : home.listFiles(mAudioFilter))
    {
        if (file.isDirectory()) {
           mp3List(file, fileList);
        } else {
           fileList.add(file);
        }
    }
}