class Program
{
static List<Student> stuList;
static void Main(string[] args)
{
if (stuList == null)
{
Console.WriteLine("stuList is null");
}
Console.ReadKey();
}
}
public class Student
{
public string Name { get; set; }
public int Age { get; set; }
}
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方式二:is null7 y9 U9 s! v( D, U5 M! d
class Program
{
static List<Student> stuList = new List<Student>();
static void Main(string[] args)
{
//if (stuList is null)
//{
// Console.WriteLine("stuList is null");
// throw new Exception("stuList is null");
//}
//if (!stuList.Any())
//{
// Console.WriteLine("stuList is empty");
//}
stuList.Add(new Student() { Name = "zls",Age = 25});
if (stuList?.Count != 0)
{
Console.WriteLine("StuList is neither null nor empty");
}
Console.ReadKey();
}
}
public class Student
{
public string Name { get; set; }
public int Age { get; set; }
}
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这样就可以保证stuList为null的时候获取集合的数量也不会引发异常。 8 Z @, X0 E9 S: N