c# - key 不存在错误

Question

根据我的理解，评论中解释了这里应该发生的事情，但由于某种原因，我在编辑器中遇到了这个错误

KeyNotFoundException: The given key was not present in the dictionary. System.Collections.Generic.Dictionary`2[System.Int32,System.String].get_Item (Int32 key) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/Dictionary.cs:150) UpgradeManager.ScanForAvailableUpgrades () (at Assets/Scripts/UpgradeManager.cs:125 UpgradeManager.Update () (at Assets/Scripts/UpgradeManager.cs:70)

错误发生在函数 DisableSameType 被调用之后

public string GetUpgradeType(string upgradeName){
        return upgradeTypes [upgradeName];
    }

    public void DisableSameType (string upgradeName){
        string upgradeType = GetUpgradeType (upgradeName);

        string[] keys = KeyByValue (upgradeTypes, upgradeType); //returns all the keys of the same type

        if (keys.Length == 0) { //if there are no keys
            return;             //then return
        } else {
            for (int i = 0; i < keys.Length; i++) { //loop through all the keys
                upgradesOwned [keys [i]] = false;   //Set them to false
            }
        }
    }

还有其他相关代码

public List<string> AvailableUpgrades = new List<string>();

    protected Dictionary<int,string> upgradeNames = new Dictionary<int, string>();

    protected Dictionary<string,bool> upgradesOwned = new Dictionary<string, bool>();
    protected Dictionary<string,bool> upgradesPurchased = new Dictionary<string, bool>();

    protected Dictionary<string,int> upgradeCost = new Dictionary<string, int>(); 

    /* UPGRADE TYPES
     * Title
     * Layout
     * Scoreboard
     * VisualCountdown
     */
    protected Dictionary<string,string> upgradeTypes = new Dictionary<string, string>();

protected bool IsPurchased(string upgradeName){
    return upgradesPurchased [upgradeName];
}

public static string[] KeyByValue(Dictionary<string, string> dict, string val)
    {
        string key = null;
        foreach (KeyValuePair<string, string> pair in dict)
        {
            if (pair.Value == val)
            { 
                key += pair.Key + "|"; 
                break; 
            }
        }
        return key.Split('|');
    }

protected void ScanForAvailableUpgrades(){
        AvailableUpgrades.Clear ();                                             //Clear the list
        int scanRange = GetUnits() + GameManager.Instance.scanRange;            //Get the range by adding the scanRange to current units
        for (int i = 0; i < upgradesOwned.Count; i++) {                     //Loop through all upgrades
            if (IsPurchased (upgradeNames [i])) {
                //return
            } else {
                if (scanRange >= upgradeCost [upgradeNames [i]]) {                      //Check if the cost is within the scanrange
                    if (AvailableUpgrades.Contains (upgradeNames [i])) {                //Check if upgrade is already in the available list
                        //return;                                                   //If it is we just return
                    } else {                                                        //Else
                        if (upgradesOwned [upgradeNames [i]]) {                 //Check if the user already has the upgrade *NOTE* Should probaby check for this first to improve performance
                            //return;                                               //If it is return
                        } else {                                                    //Else
                            AvailableUpgrades.Add (upgradeNames [i]);                   //Upgrade does not exist and is not bought so add it to the available list
                        }
                    }
                }
            }
        }
    }

进一步调试后，我发现 Debug.Log(keys[i]); 将第一个字符串返回为“basicTitle|”并且字符串字符串为空

编辑:我可以看到我的问题在哪里似乎具有误导性第 125 行是这一行 if (IsPurchased (upgradeNames [i])) { 但是我已经经历过并且在注释掉“DisableSameType”之后错误消失了方法DisableSameType 是一个新函数，错误直到它被实现后才开始发生，所以我 100% 肯定这是错误的来源我只是不确定是什么导致了它

Answer 1

upgradesOwned 字典中没有有效的key。
在将 key value 设置为 false 之前，您应该检查 dictionary 是否有 key。如果它有键那么你可以把它设为false，否则你需要在字典中添加一个键值对。
所以，而不是你的代码中的这一行:

upgradesOwned [keys [i]] = false;   //Set them to false

应该是这样的:

if(upgradesOwned.ContainsKey(keys[i])){
    upgradesOwned [keys [i]] = false;   //Set them to false
}else{
    upgradesOwned.Add(keys [i],false);   //Add new key and set them to false
}