字段初始值设定项不能引用非静态字段、方法或属性 [英] A field initializer cannot reference the nonstatic field, method, or property

问题描述

我有一个课程，当我尝试在另一个课程中使用它时，我收到以下错误.

使用系统；使用 System.Collections.Generic;使用 System.Linq；命名空间 MySite{公开课提醒{公共字典<TimeSpan, string>时间跨度文本 { 获取；放;}//我们正在使用 Costructor 设置默认值公开提醒(){TimeSpanText.Add(TimeSpan.Zero, "None");TimeSpanText.Add(new TimeSpan(0, 0, 5, 0), "5 分钟前");TimeSpanText.Add(new TimeSpan(0, 0, 15, 0), "15 分钟前");TimeSpanText.Add(new TimeSpan(0, 0, 30, 0), "30 分钟前");TimeSpanText.Add(new TimeSpan(0, 1, 0, 0), "1 小时前");TimeSpanText.Add(new TimeSpan(0, 2, 0, 0), "2 小时前");TimeSpanText.Add(new TimeSpan(1, 0, 0, 0), "1 天前");TimeSpanText.Add(new TimeSpan(2, 0, 0, 0), "2 天前");}}}

在另一个类中使用该类

class SomeOtherClass{私人提醒提醒 = new Reminders();//错误发生在这一行:私人动态 defaultReminder = 提醒.TimeSpanText[TimeSpan.FromMinutes(15)];....

错误(CS0236):

字段初始值设定项不能引用非静态字段、方法或属性

为什么会发生这种情况以及如何解决?

解决方案

这一行:

private dynamic defaultReminder =提醒.TimeSpanText[TimeSpan.FromMinutes(15)];

您不能使用实例变量来初始化另一个实例变量.为什么?因为编译器可以重新排列这些 - 不能保证 reminder 会在 defaultReminder 之前被初始化，所以上面的行可能抛出一个 NullReferenceException.

相反，只需使用:

private dynamic defaultReminder = TimeSpan.FromMinutes(15);

或者，在构造函数中设置值:

私有动态默认提醒；公开提醒(){defaultReminder = prompt.TimeSpanText[TimeSpan.FromMinutes(15)];}

MSDN 上有关于此编译器错误的更多详细信息 - 编译器错误 CS0236.>

I have a class and when I try to use it in another class I receive the error below.

using System;
using System.Collections.Generic;
using System.Linq;

namespace MySite
{
    public class Reminders
    {
        public Dictionary<TimeSpan, string> TimeSpanText { get; set; }

        // We are setting the default values using the Costructor
        public Reminders()
        {
            TimeSpanText.Add(TimeSpan.Zero, "None");
            TimeSpanText.Add(new TimeSpan(0, 0, 5, 0), "5 minutes before");
            TimeSpanText.Add(new TimeSpan(0, 0, 15, 0), "15 minutes before");
            TimeSpanText.Add(new TimeSpan(0, 0, 30, 0), "30 minutes before");
            TimeSpanText.Add(new TimeSpan(0, 1, 0, 0), "1 hour before");
            TimeSpanText.Add(new TimeSpan(0, 2, 0, 0), "2 hours before");
            TimeSpanText.Add(new TimeSpan(1, 0, 0, 0), "1 day before");
            TimeSpanText.Add(new TimeSpan(2, 0, 0, 0), "2 day before");
        }

    }
}

Using the class in another class

class SomeOtherClass
{  
    private Reminders reminder = new Reminders();
    // error happens on this line:
    private dynamic defaultReminder = reminder.TimeSpanText[TimeSpan.FromMinutes(15)]; 
    ....

Error (CS0236):

A field initializer cannot reference the nonstatic field, method, or property

Why does it happen and how to fix it?

解决方案

This line:

private dynamic defaultReminder = 
                          reminder.TimeSpanText[TimeSpan.FromMinutes(15)];

You cannot use an instance variable to initialize another instance variable. Why? Because the compiler can rearrange these - there is no guarantee that reminder will be initialized before defaultReminder, so the above line might throw a NullReferenceException.

Instead, just use:

private dynamic defaultReminder = TimeSpan.FromMinutes(15);

Alternatively, set up the value in the constructor:

private dynamic defaultReminder;

public Reminders()
{
    defaultReminder = reminder.TimeSpanText[TimeSpan.FromMinutes(15)]; 
}

There are more details about this compiler error on MSDN - Compiler Error CS0236.

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