Android MusicPlayer 4

MainActivity.java

        mp.seekTo(0);
        mp.setVolume(0.5f, 0.5f);
        totalTime = mp.getDuration();

        // 再生位置
        positionBar = findViewById(R.id.positionBar);
        positionBar.setMax(totalTime);
        positionBar.setOnSeekBarChangeListener(
                new SeekBar.OnSeekBarChangeListener() {
                    @Override
                    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                        if (fromUser) {
                            mp.seekTo(progress);
                            positionBar.setProgress(progress);
                        }
                    }

                    @Override
                    public void onStartTrackingTouch(SeekBar seekBar) {

                    }

                    @Override
                    public void onStopTrackingTouch(SeekBar seekBar) {

                    }
                }
        );

        // 音量調節
        volumeBar = findViewById(R.id.volumeBar);