尝试设置类属性时出现 NullReferenceException

NullReferenceException when trying to set class property(尝试设置类属性时出现 NullReferenceException)

问题描述

基本上我有 2 个类，Manifest"和BrowserAction"，如下所示:

Basically I have 2 classes, "Manifest" and "BrowserAction", set out like this:

public class BrowserAction
{
    public string default_icon {get; set;}
    public string default_title {get; set;}
    public string default_popup {get; set;}
}


public class Manifest
{
    public BrowserAction browser_action {get; set;}
}

问题是，当我尝试设置 Manifest 类的 browser_action.default_popup 的实例时，如下所示:

The problem is, that when I try to set an instance of the Manifest class' browser_action.default_popup, like this:

public void setManifest()
{
    Manifest newManifest = new Manifest();
    newManifest.browser_action.default_popup = "popup.html";
}

我得到一个 System.NullReferenceException.我环顾四周，但似乎找不到问题所在.它适用于Manifest"类的其他属性，这些属性只是字符串等.

I get a System.NullReferenceException. I've looked around but I can't seem to find what the problem is. It works fine for other properties of the "Manifest" class that are just strings etc.

如果相关，我的 IDE 是 MonoDevelop 2.4，我的框架是 Mono 2.6.7.

If it's relevant, my IDE is MonoDevelop 2.4, with Mono 2.6.7 for my framework.

推荐答案

在访问该实例的属性之前，您还必须初始化 browser_action.

You'll have to intialize browser_action too before accessing properties on that instance.

newManifest.browser_action= new BrowserAction();

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