如何对可能为空的对象执行ToString？

string result = obj ?? string.Empty;
Console.WriteLine(result.ToString());

string result = obj != null ? obj.ToString() : string.Empty;
Console.WriteLine(result);

string result = obj?.ToString() ?? string.Empty;
Console.WriteLine(result);

string result = string.Empty;
try
{
    result = obj.ToString();
}
catch (NullReferenceException)
{
    // 处理空引用异常
}
Console.WriteLine(result);

public static class ObjectExtensions
{
    public static string SafeToString(this object obj)
    {
        return obj?.ToString() ?? string.Empty;
    }
}

// 使用扩展方法
string result = obj.SafeToString();
Console.WriteLine(result);