如何在另一个活动中停止mediaPlayer？

public class FirstActivity extends AppCompatActivity {
    private MediaPlayer mediaPlayer;

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

        mediaPlayer = MediaPlayer.create(this, R.raw.audio_file);
        mediaPlayer.start();
    }

    public void stopMediaPlayer() {
        if (mediaPlayer != null && mediaPlayer.isPlaying()) {
            mediaPlayer.stop();
            mediaPlayer.release();
            mediaPlayer = null;
        }
    }
}

public class SecondActivity extends AppCompatActivity {
    private FirstActivity firstActivity;

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

        // 获取第一个活动的实例或引用
        firstActivity = ((MyApplication) getApplicationContext()).getFirstActivity();
    }

    public void stopMediaPlayerInFirstActivity() {
        if (firstActivity != null) {
            firstActivity.stopMediaPlayer();
        }
    }
}