时间戳

首页 > 解决方案 > unity Json 字符串导致空引用异常

c# - unity Json 字符串导致空引用异常

问题描述

尝试使用反向获取位置名称。我正在使用 Unity 的 JSONutility 来解析从 google API 获得的 JSON 字符串。信息不会存储在我的本地对象中，所以我总是得到一个空引用异常。

为了检索我使用 UnityWebRequest 类的信息。我将信息写入一个简单的文本文件以检查请求是否实际被发送，并且信息被写入文本文件，但是当我想用它在游戏中创建一些东西时，它不起作用。

我使用http://json2csharp.com/根据我的 JSON 文件创建了我的 C# 类。

我在这里验证了 JSON 文件https://jsonlint.com/

//This is the c# file I created out of the JSON format gotten from google
//It is validated.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;


public class RootObject
{
    public PlusCode plus_code;//This doesn't get created at all
    public List<Result> results;//This creates a list of size 11, however the list is always empty and I don't know why.
    public string status;//For some reason this is the only variable that gets populated

    public static RootObject CreateFromJSON(string jsonString)
    {
        return JsonUtility.FromJson<RootObject>(jsonString);
    }
}

public class PlusCode
{
    public string compound_code;
    public string global_code;
}

public class AddressComponent
{
    public string long_name;
    public string short_name;
    public List<string> types;
}

public class Northeast
{
    public double lat;
    public double lng;
}

public class Southwest
{
    public double lat;
    public double lng;
}

public class Bounds
{
    public Northeast northeast;
    public Southwest southwest;
}

public class Location
{
    public double lat;
    public double lng;
}

public class Northeast2
{
    public double lat;
    public double lng;
}

public class Southwest2
{
    public double lat;
    public double lng;
}

public class Viewport
{
    public Northeast2 northeast;
    public Southwest2 southwest;
}

public class Geometry
{
    public Bounds bounds;
    public Location location;
    public string location_type;
    public Viewport viewport;
}

public class PlusCode2
{
    public string compound_code;
    public string global_code;
}

public class Result
{
    public List<AddressComponent> address_components;
    public string formatted_address;
    public Geometry geometry;
    public string place_id;
    public List<string> types;
    public PlusCode2 plus_code;
}

这就是我试图调用它的地方。

public void ShowStaticMap()
        {
            //Grab GEO Data
            StartCoroutine(FetchGeoData());
            newCase.date = DateTime.Today.ToString();
            StartCoroutine(GetLocationName());//This runs.
        }


IEnumerator GetLocationName()
        {
            UnityWebRequest www = UnityWebRequest.Get(geoUrl);
            yield return www.SendWebRequest();

            if (www.isNetworkError || www.isHttpError)
            {
                Debug.Log(www.error);
            }
            else
            {
                var TestRootObject = RootObject.CreateFromJSON(www.downloadHandler.text).plus_code.compound_code;// This is line 147. Results in a nullreference exception.
/*
If I am to try this line, it will work without a problem.
RootObject.CreateFromJSON(www.downloadHandler.text).status;
*/
                Debug.Log(TestRootObject);//There is nothing here.
            }
        }

NullReferenceException：对象引用未设置为对象 est.UI.CreateCaseScreen+d__19.MoveNext () 的实例（在 Assets/Esteban/Scripts/ScreenTypes/CreateCaseScreen.cs:147） UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator枚举器，System.IntPtr returnValueAddress）（在 C:/buildslave/unity/build/Runtime/Export/Scripting/Coroutines.cs:17）

标签： c#unity3dcoroutinereverse-geocoding

解决方案

好吧...这里真的很傻。对于遇到类似问题的任何人...当您创建原始类时（就像没有从 Unity 中的任何东西继承...）确保将它们声明为 [Serializable]

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;


[Serializable] //THIS! On all your classes!!!
public class RootObject
{
    public PlusCode plus_code;
    public List<Result> results;
    public string status;

    public static RootObject CreateFromJSON(string jsonString)
    {
        return JsonUtility.FromJson<RootObject>(jsonString);
    }
}

[Serializable]
public class PlusCode
{
    public string compound_code;
    public string global_code;
}

[Serializable]
public class AddressComponent
{
    public string long_name;
    public string short_name;
    public List<string> types;
}

[Serializable]
public class Northeast
{
    public double lat;
    public double lng;
}

[Serializable]
public class Southwest
{
    public double lat;
    public double lng;
}

[Serializable]
public class Bounds
{
    public Northeast northeast;
    public Southwest southwest;
}

[Serializable]
public class Location
{
    public double lat;
    public double lng;
}

[Serializable]
public class Northeast2
{
    public double lat;
    public double lng;
}

[Serializable]
public class Southwest2
{
    public double lat;
    public double lng;
}

[Serializable]
public class Viewport
{
    public Northeast2 northeast;
    public Southwest2 southwest;
}

[Serializable]
public class Geometry
{
    public Bounds bounds;
    public Location location;
    public string location_type;
    public Viewport viewport;
}

[Serializable]
public class PlusCode2
{
    public string compound_code;
    public string global_code;
}

[Serializable]
public class Result
{
    public List<AddressComponent> address_components;
    public string formatted_address;
    public Geometry geometry;
    public string place_id;
    public List<string> types;
    public PlusCode2 plus_code;
}

推荐阅读