创建ArrayList
class Program
{
static void Main(string[] args)
{
//创建一个集合
ArrayList list = new ArrayList();
//集合：很多数据的集合
//数组：长度不可变，类型单一
//集合的好处：长度可以任意改变 类型随便
list.Add(1);
list.Add(3.14);
list.Add(true);
list.Add("张三");
list.Add('男');
list.Add(1000M);
// list.Add(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 });
for (int i = 0; i <list.Count; i++)
{
if(list[i] is int[])
{
for (int j = 0; j < ((int[])list[i]).Length; j++)
{
Console.WriteLine(((int[])list[i])[j]);
}
}
else
{
Console.WriteLine(list[i]);
}
}
Console.ReadKey();
}
}
ArrayList的长度
/*
* 每次集合中实际包含的元素个数（Count）超过了可以包含的元素的个数（Capacity）的时候，
* 集合就会向内存中申请开辟一倍的空间，来保证集合的长度一直够用
*
*/
class Program
{
static void Main(string[] args)
{
ArrayList list = new ArrayList();
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
list.Add(1);
Console.WriteLine(list.Count);
Console.WriteLine(list.Capacity);
Console.ReadKey();
}
}
ArrayList的方法
class Program
{
static void Main(string[] args)
{
ArrayList list = new ArrayList();
//添加单个元素
list.Add(true);
list.Add(1);
list.Add("张三");
//添加数组和集合
list.AddRange(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 });
//list.AddRange(list);
//清空所有元素
// list.Clear();
//删除单个元素
//list.Remove(true);//写谁删除谁
//list.RemoveAt(0);//根据下标删除元素
//list.RemoveRange(0,3);//根据下标去移除一定范围的元素
//list.Sort();//升序排序
//list.Reverse();//反转
//list.Insert(1, "插入的"); //在指定的位置插入一个元素
//list.InsertRange(0,new string[]{"李四","王五"});//在指定的位置插入一个集合
bool b = list.Contains(1);//判断是否包含某个指定的元素
if (!list.Contains("马六"))
{
list.Add("马六");
}
else
{
Console.WriteLine("已经有这个屌丝了");
}
for (int i = 0; i < list.Count; i++)
{
Console.WriteLine(list[i]);
}
Console.ReadKey();
}
}
ArrayList存放对象
/*
* 使用ArrayList集合：
* 1.引入System.Collections命名空间
* 2.实例化ArrayList对象
*
* ArrayList的方法：
* Add():添加
* Remove()删除
*
*/
class Program
{
static void Main(string[] args)
{
ArrayList students = new ArrayList(); //实例化对象
ArrayList teachers = new ArrayList(5);//可以指定长度
Student stu1 = new Student(1,"张三",18,Gender.男);
Student stu2 = new Student(2, "李四", 19, Gender.女);
Student stu3 = new Student(3, "王五", 20, Gender.男);
students.Add(stu1);
students.Add(stu2);
students.Add(stu3);
//按照索引下标取出对象
Student s1 = (Student)students[0];
s1.SayHi();
Console.ReadKey();
}
}
public class Student
{
public Student(int StuId,string Name,int Age,Gender Gender)
{
this.stuId = StuId;
this.name = Name;
this.age = Age;
this.gender = Gender;
}
public int stuId;
public string name;
public int age;
public Gender gender;
public void SayHi()
{
Console.WriteLine("大家好，我是{0},今年{1}岁,很开心认识大家",this.name,this.age);
}
}
public enum Gender
{
男,
女
}
ArrayList小练习
class Program
{
static void Main(string[] args)
{
//创建一个集合，里面添加一些数字，求平均值与和，最大值，最小值
ArrayList list = new ArrayList();
list.AddRange(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 });
int sum = 0;
int max = (int)list[0];
for (int i = 0; i < list.Count; i++)
{
if ((int)list[i] > max)
{
max = (int)list[i];
}
//父类中装有子类对象，所以，父类可以强制转换为子类对象
sum += (int)list[i];
}
Console.WriteLine(sum);
Console.WriteLine(sum / list.Count);
Console.WriteLine(max);
Console.WriteLine("---------------------------------");
//写一个长度为10的集合，要求在里面随机存放10个数字(0-9),但要求所有数字不能重复
ArrayList list2 = new ArrayList();
Random rd = new Random();
for (int i = 0; i < 10; i++)
{
int rNumber = rd.Next(0, 10);
if (!list2.Contains(rNumber))
{
list2.Add(rNumber);
}
else
{
//一旦产生了重复的随机数，这次循环就不算数了
i--;
}
}
for (int i = 0; i < list2.Count; i++)
{
Console.WriteLine(list2[i]);
}
Console.ReadKey();
}
}
HashTable创建
/*
* HashTable 健值对集合 字典 张 zhang->张
* 在键值对集合当中，我们是根据键去找值的
* 健值对对象[键]=值；
* ** 健值对集合中，键必须是唯一的，而值是可以重复的
*/
class Program
{
static void Main(string[] args)
{
//创建了一个键值对集合对象
Hashtable ht = new Hashtable();
ht.Add(1, "张三");
ht.Add(2, true);
ht.Add(3, '五');
ht.Add(false, "错误的");
ht[6] = "新来的"; //这也是一种添加数据的方式
ht[1] = "把张三干掉";
//abc--->cba
if (!ht.ContainsKey("abc"))
{
ht.Add("abc", "cba");
}
else
{
Console.WriteLine("已经包含了这个键");
}
// ht.Clear();//清除健值集合
// ht.Remove(3);//根据键去移除里面的元素
foreach (var item in ht.Keys)
{
Console.WriteLine("键是:{0}================>值是:{1}", item, ht[item]);
}
//在键值对集合中，是根据键去找值的
//Console.WriteLine(ht[1]);
//Console.WriteLine(ht[2]);
//Console.WriteLine(ht[3]);
//Console.WriteLine(ht[false]);
//for (int i = 0; i < ht.Count; i++)
//{
// Console.WriteLine(ht[i]);
//}
Console.ReadKey();
}
}
HashTable练习
class Program
{
static void Main(string[] args)
{
Hashtable ht = new Hashtable();
while (true)
{
// Console.BackgroundColor = ConsoleColor.Red;
Console.ForegroundColor = ConsoleColor.Cyan;
Console.WriteLine("==============请选择操作================");
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(" 1.添加联系人 2.查找");
Console.ForegroundColor = ConsoleColor.Cyan;
Console.WriteLine("=======================================");
Console.Write("请输入你的选择：");
string f = Console.ReadLine();
switch (f)
{
case "1":
Console.WriteLine("请输入联系人名字：");
string name = Console.ReadLine();
Console.WriteLine("请输入联系人电话：");
string tel = Console.ReadLine();
if (ht.ContainsKey(name))
{
Console.WriteLine("该联系人已经存在", "错误");
return;
}
ht.Add(name, tel);
Console.WriteLine($"*******共有{ht.Count}位联系人************");
break;
case "2":
Console.Write("请输入要查找的联系人姓名：");
string nameFind = Console.ReadLine();
object telFind = ht[nameFind];
//用联系人名称作为索引来获得对应的联系人电话
if (telFind == null)
{
Console.WriteLine("该联系人不存在", "错误");
}
else
{
Console.WriteLine($"你所查找的联系人电话是：{telFind}");
}
break;
}
}
}
}
List泛型集合
/*
* 泛型集合就是明确指定了要放入集合的对象是何种类型的集合
*
*/
class Program
{
static void Main(string[] args)
{
//创建泛型集合对象
List<int> list = new List<int>();
list.Add(1);
list.Add(2);
list.Add(3);
list.AddRange(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 });
list.AddRange(list);
//List泛型集合可以转换成数组
int[] nums = list.ToArray();
List<string> listStr = new List<string>();
string[] strs = listStr.ToArray();
for (int i = 0; i < list.Count; i++)
{
Console.WriteLine(list[i]);
}
Console.ReadKey();
}
}
List泛型集合练习
class Program
{
static void Main(string[] args)
{
Student s1 = new Student(1, "张三");
Student s2 = new Student(2, "李四");
Student s3 = new Student(3, "王五");
// List<Student> students = new List<Student> { s1, s2, s3, 1 };
//集合初始化器
List<Student> students = new List<Student> { s1, s2, s3};
//foreach (var item in students)
//{
// Console.WriteLine(item.Say());
//}
//ForEach()结合Lambda表达式实现循环遍历
students.ForEach(s => { Console.WriteLine(s.Say()); });
//FindAll方法检索条件匹配的所有元素
List<Student> _students = students.FindAll(m=>m.Id<3);
Console.WriteLine("学号小于3的学生如下：");
_students.ForEach(s => { Console.WriteLine(s.Say()) ; });
Console.ReadKey();
}
}
public class Student
{
public Student(int id,string name)
{
this.Id = id;
this.Name = name;
}
//自动属性
public int Id { get; set; }
public string Name { get; set; }
public string Say()
{
return "姓名" + Name + ",学号" + Id;
}
}
Dictionary字典集合创建
class Program
{
static void Main(string[] args)
{
Dictionary<int, string> dic = new Dictionary<int, string>();
dic.Add(1, "张三");
dic.Add(2, "李四");
dic.Add(3, "王五");
dic[1] = "新来的";
//foreach(var item in dic.Keys)
//{
// Console.WriteLine("{0}-----{1}", item, dic[item]);
//}
foreach (KeyValuePair<int, string> kv in dic)
{
Console.WriteLine("{0}--------------{1}", kv.Key, kv.Value);
}
Console.ReadKey();
}
}
泛型集合常用的扩展方法
class Program
{
static void Main(string[] args)
{
Student s1 = new Student(1, "贾宝玉");
Student s2 = new Student(2, "林黛玉");
Student s3 = new Student(3, "薛宝钗");
Student s4 = new Student(4, "史湘云");
//创建泛型集合
List<Student> students = new List<Student>() { s1, s2, s3, s4 };
//获取泛型集合中第一个元素，如果泛型内没有元素，则返回null
//需引入System.Linq命名空间
var student1 = students.FirstOrDefault();
Console.WriteLine($"集合中第一个元素的名字是:{student1.Name},其Id是{student1.Id}");
//判断泛型集合中是不是每个元素的ID都大于0，如果是返回true
bool b = students.All(s => s.Id > 0);
Console.WriteLine($"全部学生的ID都大于0：{b}");
//首先通过where过滤出泛型集合中所有ID大于3的Student,然后再对返回的值求其中的个数
int count = students.Where(s => s.Id > 3).Count();
Console.WriteLine($"集合中Id大于3的学生的个数是：{count}");
Console.ReadKey();
}
}
public class Student
{
public Student(int id,string name)
{
this.Id = id;
this.Name = name;
}
public int Id { get; set; }
public string Name { get; set; }
}
IComparable接口实现排序
//List<string> list = new List<string> { "张三", "李四", "王五" };
//Console.WriteLine("排序前顺序");
//foreach (var str in list)
//{
// Console.WriteLine(str);
//}
//list.Sort();//按首字符的升序进行排序
//Console.WriteLine("排序后顺序");
//foreach (var str in list)
//{
// Console.WriteLine(str);
//}
Student stu1 = new Student(1,"张三",19);
Student stu2 = new Student(2, "李四", 18);
Student stu3 = new Student(3, "王五", 20);
List<Student> list = new List<Student>() { stu1,stu2,stu3};
Console.WriteLine("排序前顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
list.Sort();
Console.WriteLine("排序后顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
Console.ReadKey();
}
}
//3.实现IComparable接口
public class Student:IComparable
{
public Student(int StuId, string Name, int Age)
{
this.stuId = StuId;
this.name = Name;
this.age = Age;
}
public int stuId;
public string name;
public int age;
//实现IComparable接口的CompareTo()方法
public int CompareTo(object obj)
{
//判断接受的参数是否为Student类的对象
if(!(obj is Student))
{
throw new Exception("比较对象不是Student对象");
}
Student other = obj as Student;
//把当前对象的name成员和接受的参数的name成员进行比较，返回结果
//返回类型是Int 类型 返回值大于0 表示当前对象大于obj，小于0 ，表示当前对象小于obj,
return this.name.CompareTo(other.name);
}
}
IComparable泛型接口
class Program
{
static void Main(string[] args)
{
Student stu1 = new Student(1, "张三", 19);
Student stu2 = new Student(2, "李四", 18);
Student stu3 = new Student(3, "王五", 20);
List<Student> list = new List<Student>() { stu1, stu2, stu3 };
Console.WriteLine("排序前顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
list.Sort();
Console.WriteLine("排序后顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
Console.ReadKey();
}
}
//3.实现IComparable<T>泛型接口
public class Student : IComparable<Student>
{
public Student(int StuId, string Name, int Age)
{
this.stuId = StuId;
this.name = Name;
this.age = Age;
}
public int stuId;
public string name;
public int age;
//实现IComparable接口的CompareTo()方法
public int CompareTo(Student other)
{
return this.age.CompareTo(other.age);
}
}
IComparer泛型接口练习
class Program
{
static void Main(string[] args)
{
Student stu1 = new Student(1, "张三", 19);
Student stu2 = new Student(2, "李四", 18);
Student stu3 = new Student(3, "王五", 20);
List<Student> list = new List<Student>() { stu1, stu2, stu3 };
Console.WriteLine("排序前顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
Console.WriteLine("请选择：1.按姓名排序;2.按年龄排序");
string select = Console.ReadLine();
switch (select)
{
case "1":
//按照姓名排序
list.Sort(new NameSort());
break;
case "2":
//按年龄排序
list.Sort(new AgeSort());
break;
}
Console.WriteLine("排序后顺序");
foreach (Student stu in list)
{
Console.WriteLine($"姓名：{stu.name},年龄{stu.age}");
}
Console.ReadKey();
}
}
public class Student
{
public Student(int StuId, string Name, int Age)
{
this.stuId = StuId;
this.name = Name;
this.age = Age;
}
public int stuId;
public string name;
public int age;
}
//按照姓名首字母升序类
public class NameSort : IComparer<Student>
{
//按照姓名首字符升序排列
public int Compare(Student x, Student y)
{
return x.name.CompareTo(y.name);
}
}
//按照年龄升序类
public class AgeSort : IComparer<Student>
{
//按照姓名首字符升序排列
public int Compare(Student x, Student y)
{
return x.age.CompareTo(y.age);
}
}
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