重定向时出现错误 [英] I Get an error when Redirecting

问题描述

你好，
我有一个名为Redirector.cs
的类

 公共  class 重定向器:IRedirector
{
    公共 无效 GoToAccountRegisterPage()
    {
       重定向(" )；
    }
    私有 无效重定向(字符串路径)
    {
        HttpContext.Current.Response.Redirect(path);
    }
}

这是Redirector.cs的界面.

  public   interface  IRedirector
    {
        无效 GoToAccountRegisterPage();

    } 

这是另一个Web表单..Go.aspx
单击链接后，它应该转到另一页.该链接的类为

 GoToRegister()

这是我的CS代码

 公共 类  LoginPresenter 
    {
        私有  IRedirector   _ redirector  = null;
         公共 无效 GoToRegister()
        {
             _ redirector  . GoToAccountRegisterPage();
        } 
    }  

但是当我单击网页上的链接时，出现这样的错误

对象引用未设置为对象的实例.
异常详细信息:System.NullReferenceException:对象引用未设置为对象的实例.

源错误:

Line 31:         public void GoToRegister()
Line 32:         {
Line 33:             _redirector.GoToAccountRegisterPage();
Line 34:         }
Line 35: 

有人可以告诉我为什么吗..我可以做什么！！

谢谢.

解决方案

调用GoToRegister 方法时，_redirector仍然为null.这就是为什么您会得到例外.

您应该在代码的适当部分设置_redirector 的值，并在GoToRegister 方法中使用_redirector 之前应检查_redirector 是否为null.

Hello,
I have a class called Redirector.cs

public class Redirector : IRedirector
{
    public void GoToAccountRegisterPage()
    {
       Redirect("~/Account/Register.aspx");
    }
    private void Redirect(string path)
    {
        HttpContext.Current.Response.Redirect(path);
    }
}

This is my interface for Redirector.cs

public interface IRedirector
    {
        void GoToAccountRegisterPage();

    }

This an another web form..Go.aspx
Once you click a Link it should go to another page..the link''s class is

GoToRegister()

this is my cs code

public class LoginPresenter
    {
        private IRedirector _redirector = null;
         public void GoToRegister()
        {
            _redirector.GoToAccountRegisterPage();
        }
    }

But wen i click the link on the web page i get an error like this

Object reference not set to an instance of an object.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 31:         public void GoToRegister()
Line 32:         {
Line 33:             _redirector.GoToAccountRegisterPage();
Line 34:         }
Line 35: 

Can someone tell me why is this.. and wat can i do!!

Thank you.

解决方案

When the GoToRegister method is called, the _redirector is still null . That''s why you get the exception.

You should set the value of the _redirector (in proper part of your code) and in the GoToRegister method you should check if _redirector is null or not before using it.

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