public class FileManagerActivity extends Activity {
    private ListView lvFileList;
    private FileListAdapter mAdapter;

    private File mCurFile;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_files);

        if (!Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            Toast.makeText(this, "Cannot read external storage, sorry",
                    Toast.LENGTH_SHORT).show();
            finish();
        }

        File sd = Environment.getExternalStorageDirectory();
        mCurFile = sd;

        FileFilter filter = new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                return pathname.isDirectory()
                        || pathname.getName().endsWith(".mp3")
                        || pathname.getName().endsWith(".MP3");
            }
        };

        File[] sdDirList = sd.listFiles(filter);

        lvFileList = (ListView) findViewById(R.id.lvFileList);

        mAdapter = new FileListAdapter(this, sdDirList);
        lvFileList.setAdapter(mAdapter);

        lvFileList.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                File file = mAdapter.getItem(position);
                if (file.isDirectory()) {
                    mAdapter = new FileListAdapter(getApplicationContext(),
                            file.listFiles());
                    lvFileList.setAdapter(mAdapter);
                    mCurFile = file;
                } else {
                    Toast.makeText(getApplicationContext(),
                            "Press \"Select this folder\"", Toast.LENGTH_SHORT)
                            .show();
                }
            }
        });
    }

    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.btnSelectFolder:
            SongsManager.get(this).setCurrentPlaylistFromFolder(mCurFile);
            setResult(RESULT_OK);
            finish();
            break;
        default:
            break;
        }
    }

    private class FileListAdapter extends ArrayAdapter<File> {
        private File[] mFiles;

        public FileListAdapter(Context context, File[] objects) {
            super(context, 0, objects);
            mFiles = objects;
        }

        @Override
        public File getItem(int position) {
            return mFiles[position];
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = getLayoutInflater().inflate(
                        R.layout.list_files_item, null, false);
            }

            File file = mFiles[position];

            ((TextView) convertView.findViewById(R.id.tvName)).setText(file
                    .getName());
            int icon = file.isDirectory() ? R.drawable.ic_folder
                    : R.drawable.ic_note;
            ((ImageView) convertView.findViewById(R.id.ivIcon))
                    .setImageResource(icon);

            return convertView;
        }
    }
}