问无法使均衡器工作！它什么也做不了

EN

// create : media player + equalizer
private void init() {
    Log.d(TAG, "initMediaPlayer: ");
    try {
        mediaPlayer = new MediaPlayer();
        equalizer = new Equalizer(0, mediaPlayer.getAudioSessionId());
        if (equalizer.setEnabled(true) != Equalizer.SUCCESS) {
            Log.d(TAG, "initMediaPlayer: FAILED");
            return;
        }
        equalizer.usePreset((short) 0);
    } catch (Exception e) {
        Log.e(TAG, "initMediaPlayer: ", e);
    }
}


// use next preset
private void useNextPreset() {
    short presetCount = equalizer.getNumberOfPresets();
    short index = equalizer.getCurrentPreset();
    index++;
    if (index >= presetCount) index = 0;
    equalizer.usePreset(index);
    Log.d(TAG, "useNextPreset: " + equalizer.getPresetName(index));
}

// show music picker
private void popPicker() {
    popActivity(FilePickerIntent("audio/*"), new IntentRequestResultForward() {
        @Override
        public void onResult(boolean ok, Intent data) {
            if (ok) play(data.getData());
        }
    });
}

// play music from uri
private void play(Uri uri) {
    mediaPlayer.reset();
    try {
        mediaPlayer.setDataSource(getApplicationContext(), uri);
        mediaPlayer.prepare();
        mediaPlayer.start();
        Log.d(TAG, "play: playing...");
    } catch (Exception e) {
        Log.e(TAG, "play: error ", e);
    }
}