我的Windows窗体应用程序的null引用异常错误

Question

我有一个包含信息

的Setting.cs文件

[Serializable]
public class Setting
{
    public Setting()     {}

    public String defaultAlertTone = Path.GetDirectoryName(Application.ExecutablePath) + "\\Sounds\\applause-2.wav";        
}

和我的settingsForm通过此代码检索信息

Setting settingObject;
public SoundPlayer player;

public settingsForm(backgroundForm backgroundFormObject)
{
    InitializeComponent();
    this.backgroundFormObject = backgroundFormObject;
    settingObject = backgroundFormObject.getSetting();
}

private void InitializeSound()
{
    // Create an instance of the SoundPlayer class.
    player = new SoundPlayer();
    player.SoundLocation = settingObject.defaultAlertTone;

    // Listen for the LoadCompleted event.
    player.LoadCompleted += new AsyncCompletedEventHandler(player_LoadCompleted);

    // Listen for the SoundLocationChanged event.
    player.SoundLocationChanged += new EventHandler(player_LocationChanged);
}

为什么每次运行应用程序时，

上都会出现空引用异常

player.SoundLocation = settingObject.defaultAlertTone;

backgroundFormObject.getSetting();只是一种检索设置对象的方法。它的代码如下

Setting settingObj = new Setting();

public Setting getSetting()
    {
        return settingObj;
    }

Answer 1

原因可能是

1. InitializeSound()以某种方式在settingsForm之前运行（不太可能，但这会使settingObject未初始化并引用null）。
2. 如果这是Setting课程的完整代码，我看不到在任何地方调用new Setting()会有什么影响。因此，当您在Setting settingObject = new Setting();类中首次定义此属性时，请使用settingsForm。
3. settingObject不是null。