C#学习之利用泛型实现列表功能

引言：小生今日分享的是如何利用泛型来实现列表的功能，如果发现有描述错误，请评论告知，不甚感谢！开发版本：VS 2017 适合人群：初学Unity者开启学习之旅吧！

1 什么是泛型？

通过参数化类型来实现在同一份代码上操作多种数据类型，利用“参数化类型”将类型抽象化，实现代码的灵活复用。（推荐泛型学习博客：https://www.cnblogs.com/hhzblogs/p/7820005.html）

2 实现功能

首先需要创建一个接口，规定要实现列表的方法

interface IListDS<T>
{
//判断列表是否为空
bool IsEmpty();
//添加元素
void Add(T item);
//获取容量大小
int GetCapacity();
//在指定位置插入元素
void Insert(int index,T item);
//获取指定位置的元素
T GetItem(int index);
//通过索引器访问,修改元素
T this[int index] { get; set; }
//返回第一个该元素的索引
int IndexOf(T item);
//返回最后一个该元素的索引
int LastIndexOf(T item);
//对列表进行排序
void Sort();
//移除第一个该元素
void Remove(T item);
//移除指定位置的元素
void RemoveAt(int index);
//清空列表
void Clear();
}

新建一个NewList类，继承IListDS<T> 接口，实现列表具体的功能

class NewList<T> : IListDS<T> where T : IComparable//泛型约束
{
private T[] data;
private int count;
public int Count
{
get
{
return this.count;
}
}
public int Capacity
{
get
{
return data.Length;
}
}
public NewList(int size)
{
if (size >= 0)
{
data = new T[size];
}
}
//定义一个无参构造函数，默认数组大小为0
public NewList() : this(0) { }
public T this[int index]
{
get
{
return GetItem(index);
}
set
{
if (index >= 0 && index <= Count - 1)
{
data[index] = value;
}
else
{
throw new Exception("IndexOutOfRangeException");
}
}
}

public void Add(T item)
{
if (Count == Capacity)
{
if (Capacity == 0)
{
data = new T[4];
}
else
{
T[] newArray = new T[Capacity * 2];
Array.Copy(data, newArray, Count);//复制前Count个元素到newArray
data = newArray;
}
}
data[Count] = item;
count++;
}
public int GetCapacity()
{
return Capacity;
}
public void Clear()
{
count = 0;
}
public T GetItem(int index)
{
if (index >= 0 && index <= Count - 1)
{
return data[index];
}
else
{
throw new Exception("IndexOutOfRangeException");
}
}
public void Insert(int index, T item)
{
if (index >= 0 && index <= Count - 1)
{
if (Count == Capacity)//容量不够的情况,需先进行扩容
{
if (Capacity == 0)
{
data = new T[4];
}
else
{
T[] newArray = new T[Capacity * 2];
Array.Copy(data, newArray, count);
data = newArray;
}
}
for (int i = count - 1; i >= index; i--)
{
data[i + 1] = data[i];
}
data[index] = item;
count++;
}
else
{
throw new Exception("IndexOutOfRangeException");
}
}
public bool IsEmpty()
{
return count == 0;
}
public int IndexOf(T item)
{
for (int i = 0; i < count; i++)
{
if (item.Equals(data[i]))
{
return i;
}
}
return -1;
}
public int LastIndexOf(T item)
{
for (int i = count - 1; i >= 0; i--)
{
if (item.Equals(data[i]))
{
return i;
}
}
return -1;
}
public void Remove(T item)
{
for (int i = 0; i < Count; i++)
{
if (item.Equals(data[i]))
{
RemoveAt(i);
break;
}
}
}
public void RemoveAt(int index)
{
if (index >= 0 && index <= Count - 1)
{
for (int i = index + 1; i < count; i++)
{
data[i - 1] = data[i];
}
count--;
}
else
{
throw new Exception("IndexOutOfRangeException");
}
}
public void Sort()
{
bool isOrder = false;
do
{

4000
isOrder = true;
for (int i = 0; i < Count - 1; i++)
{
if (data[i].CompareTo(data[i + 1]) > 0)
{
T temp = data[i + 1];
data[i + 1] = data[i];
data[i] = temp;
isOrder = false;
}
}
}
while (!isOrder);
}
}

在Program类的Main方法类，检测列表功能是否正确

class Program
{
static void Main(string[] args)
{
NewList<string> strList = new NewList<string>();
strList.Add("Hello");
strList.Add("World");
strList.Add("123");
strList.Add("456");
Console.WriteLine("Count:" + strList.Count + " Capacity:" + strList.Capacity);
strList.Add("789");
strList[4] = "777";
strList.Insert(3,"777");
strList.RemoveAt(1);
strList.Remove("777");
Console.WriteLine("Count:" + strList.Count + " Capacity:" + strList.Capacity);
for (int i = 0; i < strList.Count; i++)
{
Console.Write(strList[i] + " ");
}
strList.Insert(0, "777");
int index = strList.IndexOf("777");
int lastIndex = strList.LastIndexOf("777");
Console.WriteLine("\nIndex:" + index+" lastIndex:"+lastIndex);
for (int i = 0; i < strList.Count; i++)
{
Console.Write(strList[i] + " ");
}
string isEmpty = strList.IsEmpty() ? "true" : "false";
Console.WriteLine("\nisEmpty:" + isEmpty);
strList.Clear();
isEmpty = strList.IsEmpty() ? "true" : "false";
Console.WriteLine("isEmpty:" + isEmpty);
Console.WriteLine("Count:" + strList.Count + " Capacity:" + strList.Capacity);
Console.ReadKey();
}
}