c# - NullException 错误。帮助一个菜鸟

Question

有人可以告诉我这里哪里出错了吗？我不断收到错误消息：

“ArgumentNullException 未处理。此方法不接受此参数的 null。参数名称：song”

我找不到解决办法。

Song BGmusic;
bool songstart = false;

protected override void LoadContent()
{
    currentgamescreen = Gamescreen.menuscreen;

    if (!songstart)
    {
        MediaPlayer.Play(BGmusic);
    }

    BGmusic = Game.Content.Load<Song>("audio/rockTheDragon");
}

Answer 1

好吧，您调用尚未初始化的地方，因此为空MediaPlayer.Play(BGmusic);。BGmusic

可能使它像：

protected override void LoadContent()
{
    currentgamescreen = Gamescreen.menuscreen;

    if (!songstart)
    {
        BGmusic = Game.Content.Load<Song>("audio/rockTheDragon");
        MediaPlayer.Play(BGmusic);
    }
 }

会解决一个问题。

Answer 2

您在MediaPlayer.Play(BGmusic)为BGmusic. 尝试以下操作：

Song BGmusic;
bool songstart = false;

protected override void LoadContent()
{
    currentgamescreen = Gamescreen.menuscreen;

    BGmusic = Game.Content.Load<Song>("audio/rockTheDragon");

    if (!songstart)
    {
        MediaPlayer.Play(BGmusic);
    }
 }

Answer 3

移动

 BGmusic = Game.Content.Load<Song>("audio/rockTheDragon");

到该方法的顶部