Question

我的代码段如下：

public class Database {
    // fake class 
    public class databaseEntry
    {
        public Notification myNotification { get; set; }
        private string myStatus { get; private set; }
    }

    // fake notifications
    Notification notification1 = new Notification();
    Notification notification2 = new Notification();

    // fake database of type databaseEntry in List data structure
    List<databaseEntry> myDatabase = new List<databaseEntry>();

    // add fake data to fake database
    myDatabase.Add( new databaseEntry() { myNotification = notification1, myStatus = "approved"});
    myDatabase.Add( new databaseEntry() { myNotification = notification2, myStatus = "pending"});

    }

目前的问题是CS0103：名称＆＃34; myDatabase＆＃34;在最后两行代码的当前上下文中不存在。

显然我已经实现了#d; myDatabase＆＃34;，所以我不明白为什么Visual Studio会这样说＆＃34; myDatabase＆＃34;不存在。

我粗鲁地跟着示例提供了 https://msdn.microsoft.com/en-us/library/3wcytfd1(v=vs.110).aspx

Answer 1

使用ctor
每个都需要两个到现在的弹出列表你没有myStaus，通知有问题一个有自己列表的类是奇数

public class Database {
// fake class 
public class databaseEntry
{
    public Notification myNotification { get; set; }
    private string myStatus { get; private set; }
}

// fake notifications
Notification notification1 = new Notification();
Notification notification2 = new Notification();

// fake database of type databaseEntry in List data structure
List<databaseEntry> myDatabase = new List<databaseEntry>();

public DataBase() 
{
    // need to do it in the ctor
    // add fake data to fake database
    myDatabase.Add( new databaseEntry(true) { myNotification = notification1, myStatus = "approved"});
    myDatabase.Add( new databaseEntry(false) { myNotification = notification2, myStatus = "pending"});
}

public DataBase(bool skip) 
{
}

}

Answer 2

您必须将构造函数中的这些databaseEntry项添加到List<T>。在C＃中无法以这种方式在类中添加它们。您可以创建一个类型的实例，但不能在其上调用方法。

public class Database {
    //fake class
    public class databaseEntry
    {
        public Notification myNotification { get; set; }
        private string myStatus { get; private set; }
    }

    //constructor of your DataBase class
    public DataBase(){
        // add fake data to fake database
        myDatabase.Add( new databaseEntry() { myNotification = notification1, myStatus = "approved"});
        myDatabase.Add( new databaseEntry() { myNotification = notification2, myStatus = "pending"});

    }

    // fake notifications
    Notification notification1 = new Notification();
    Notification notification2 = new Notification();

    // fake database of type databaseEntry in List data structure
    List<databaseEntry> myDatabase = new List<databaseEntry>();

}

另一种方式是列表初始化程序。在那里，您可以避免构造函数并直接在List<T>定义中添加项目。除了调用Add之外，此初始化程序不起作用，但您可以直接在字段定义中使用它。

List<databaseEntry> myDatabase = new List<databaseEntry>(){
    new databaseEntry() { myNotification = notification1, myStatus = "approved"},
    new databaseEntry() { myNotification = notification2, myStatus = "pending"},
};

如何在同一个类和文件中添加列表对象？

2 个答案: