System.TypeInitializationException：“提示”的类型初始值设定项引发异常

Question

我正在尝试访问静态列表的值。但是，当我尝试这样做时，会引发此异常。

System.TypeInitializationException：“提示”的类型初始值设定项引发异常。 - - > System.NullReferenceException：未将对象引用设置为对象的实例

带有列表的类。

public static class Tips 
{ 
    //private List<Tip> roadtips = new List<Tip>(); 
    public static List<Tip> tips { get; set; } 

    static Tips() 
    { 
     tips.Add(new Tip("Don't use your mobile phone whilst driving", "Making or receiving a call, even using a 'hands free' phone, can distract your attention from driving and could lead to an accident. ")); 
     tips.Add(new Tip("Children", "Children often act impulsively, take extra care outside schools, near buses and ice cream vans when they might be around.")); 
     tips.Add(new Tip("Take a break", "Tiredness is thought to be a major factor in more than 10% of road accidents. Plan to stop for at least a 15 minute break every 2 hours on a long journey.")); 
     tips.Add(new Tip("Don't drink and drive", "Any alcohol, even a small amount , can impair your driving so be a safe driver don't drive and drive.")); 
     tips.Add(new Tip("Anticipate ", "Observe and anticipate other road users and use your mirrors regularly.")); 
     tips.Add(new Tip("Use car seats ", "Child and baby seats should be fitted properly and checked every trip.")); 
     tips.Add(new Tip("Keep your distance ", "Always keep a two second gap between you and the car in front.")); 
    } 
} 

这是试图访问该列表的类。

public partial class tip : PhoneApplicationPage 
{ 
    public tip() 
    { 
     InitializeComponent(); 
     Random r = new Random(); 
     int rInt = r.Next(0, 6); 
     tipname.Text = Tips.tips[rInt].Name; 
     tipdesc.Text = Tips.tips[rInt].Description; 
    } 
} 

这是什么原因引起的？有没有更好的方法来存储这些提示。我只需要在Windows电话页面上输出两个文本块的提示列表。

Answer 1

它看起来并不像您曾经将自动实现的属性tips初始化为一个值。因此它是null并在您的静态初始化器中导致异常。尝试初始化值

static Tips() 
{ 
    tips = new List<Tip>(); 
    ... 
} 

Answer 2

提示尚未初始化。

你需要新的它。

static Tips() 
{ 
    tips = new List<Tip>(); 
    tips.Add(new Tip("Don't use your mobile phone whilst driving", "Making or receiving 
    ... 
} 

Answer 3

public static class Tips 
{ 
    //private List<Tip> roadtips = new List<Tip>(); 
    public static List<Tip> tips { get; set; } 

    static Tips() 
    { 
     tips = new List<Tip>(); 
     tips.Add(new Tip("Don't use your mobile phone whilst driving", "Making or receiving a call, even using a 'hands free' phone, can distract your attention from driving and could lead to an accident. ")); 
     tips.Add(new Tip("Children", "Children often act impulsively, take extra care outside schools, near buses and ice cream vans when they might be around.")); 
     tips.Add(new Tip("Take a break", "Tiredness is thought to be a major factor in more than 10% of road accidents. Plan to stop for at least a 15 minute break every 2 hours on a long journey.")); 
     tips.Add(new Tip("Don't drink and drive", "Any alcohol, even a small amount , can impair your driving so be a safe driver don't drive and drive.")); 
     tips.Add(new Tip("Anticipate ", "Observe and anticipate other road users and use your mirrors regularly.")); 
     tips.Add(new Tip("Use car seats ", "Child and baby seats should be fitted properly and checked every trip.")); 
     tips.Add(new Tip("Keep your distance ", "Always keep a two second gap between you and the car in front.")); 
    } 
}