一、概述1 _7 K l- d |; q, V
当一个集合作为入参传入另外一个方法时,我们首先需要判空处理,以免在空集合上处理引发异常,判空处理的方式有多种,下面就来一一列举.3 a- C+ n8 a- T 二、是否为 null " g$ P* b' F* c) U: K9 y+ `3 P 如果一个集合没有实例化,那集合就是null,判null的常用以下几种方式: : R+ o9 z2 k; u/ [方式一:== null* Z) r# q4 i/ \7 q4 f
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; }
}
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; }
}