Parse Json to return string or string array?

Rather than returning one of two possible return types, it's probably simpler to just coerce a single string to an array containing that string. Assuming you don't control the Json, you probably want to write a custom JsonConverter. Here's my quick and dirty stab at the problem:

public class LangEntryConverter: JsonConverter<string[]>{    // WriteJson implementation only needed if you need to serialize a value back to Json    public override void WriteJson(JsonWriter writer, string[] value, JsonSerializer serializer)    {        if (value.Length == 1)        {            writer.WriteValue(value[0]);        }        else        {            writer.WriteStartArray();            for (var i = 0; i < value.Length; i++)            {                writer.WriteValue(value[i]);            }            writer.WriteEndArray();        }    }    public override string[] ReadJson(JsonReader reader, Type objectType, string[] existingValue, bool hasExistingValue, JsonSerializer serializer)    {        var values = new List<string>();        if (reader.TokenType == JsonToken.StartArray)        {            while (reader.Read() && reader.TokenType != JsonToken.EndArray)            {                if (reader.TokenType == JsonToken.String)                {                    values.Add((string)reader.Value);                }                else                {                    throw new Exception($"Unexpected token type: {reader.TokenType}");                }            }        }        else if (reader.TokenType == JsonToken.String)        {            values.Add((string)reader.Value);        }        return values.ToArray();    }}

And then call it like so:

// Note: double-quotations are required for C#'s verbatim string syntax; they are not part of the Jsonvar json = @"{  ""foo"": ""one"",  ""bar"": [""one"", ""two"", ""three""]}";var lang = JsonConvert.DeserializeObject<Dictionary<string, string[]>>(json, new LangEntryConverter());Console.WriteLine(String.Join(", ", lang["foo"]));  // oneConsole.WriteLine(String.Join(", ", lang["bar"]));  // one, two, three

Of course, in your particular situation, this may require some tweaking.

Use Generic Syntax:

 class Program<T>{  public static string langFilePath = @"..\..\..\Core\Data\Lang.json"; public static JObject lang = JObject.Parse(File.ReadAllText(langFilePath));    public static T GetJsonValue(string key)    {        T values = lang[key].ToObject<T>();        return values;    }}