尝试设置类属性时发生NullReferenceException [英] NullReferenceException when trying to set class property

问题描述

基本上我有2个类，清单"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，当我尝试设置清单类的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.对于"Manifest"类的其他属性(如字符串等)，它可以很好地工作.

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.

如果需要的话，我的IDE是MonoDevelop 2.4，而我的框架是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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