Question

我想访问一个在Main class中声明为public的变量，以访问在同一页面中创建的新类。我已经做了如下。但是无法访问该类中的变量

public sealed partial class MainPage : Page
{ 
    public bool is_arrived = false;
    public MainPage()
    {
        this.InitializeComponent();
        bool is_arrived=true;
        CallingWebServices asyn_task = new CallingWebServices();
    }
    public class CallingWebServices
    {
        //want to access variable "is_arrived" here.
    }
}

Answer 1

在这种情况下，应使用构造函数注入，并将is_arrived的值传递给CallingWebServices。

public sealed partial class MainPage : Page
{ 
    public bool is_arrived = false;
    public MainPage()
    {
        this.InitializeComponent();
        bool is_arrived=true;
        CallingWebServices asyn_task = new CallingWebServices(is_arrived);
    }
    public class CallingWebServices
    {
         private bool _isArrived;
         public CallingWebServices(bool isArrived)
         {
            _isArrived=isArrived;
         }
        //want to access variable "is_arrived" here.
    }
}

此方法的一个问题是，如果在父类中更改is_arrived值，则会失去同步。因此，另一种方法是将父类的引用传递给内部类。

public sealed partial class MainPage : Page
{ 
    public bool is_arrived = false;
    public MainPage()
    {
        this.InitializeComponent();
        bool is_arrived=true;
        CallingWebServices asyn_task = new CallingWebServices(this);
    }
    public class CallingWebServices
    {
         private MainPage _Instance;
         public CallingWebServices(MainPage instance)
         {
            _Instance=instance;
         }
        //Access variable "instance.is_arrived" here.
     }
}

但是，应避免这种做法，并应通过采用更好的设计方法来消除这种做法。

如何访问页面中声明的变量到内部类？

1 个答案: