mSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {                
                if(mMediaPlayer != null && fromUser){
                    mMediaPlayer.seekTo(progress * 1000);
                }
            }
    });

mSeekBar.setMax(mFileDuration/1000); // where mFileDuration is mMediaPlayer.getDuration();

private Handler mHandler = new Handler();
//Make sure you update Seekbar on UI thread
MainActivity.this.runOnUiThread(new Runnable() {

    @Override
    public void run() {
        if(mMediaPlayer != null){
            int mCurrentPosition = mMediaPlayer.getCurrentPosition() / 1000;
            mSeekBar.setProgress(mCurrentPosition);
        }
        mHandler.postDelayed(this, 1000);
    }
});