ArrayList に値の型を挿入するとボックス化操作がトリガーされ、次のように値の型を削除するにはボックス化を解除する必要があります
ArrayList myArrayList = new ArrayList();
myArrayList.Add(40);//装箱
myArrayList.Add(80);//装箱
Int32 a1 = (Int32)myArrayList[0];//拆箱
Int32 a2 = (Int32)myArrayList[1];//拆箱これによりパフォーマンスの消費が発生します。梱包の詳しい説明は次の記事をご覧ください。
これらの問題を解決するために、C# にはジェネリックをサポートする IList
/// <summary>
/// 泛型集合类
/// </summary>
/// <typeparam name="T"></typeparam>
public class List<T> : IList<T>, IList
{
/// <summary>
/// 泛型迭代器
/// </summary>
/// <typeparam name="T"></typeparam>
public struct Enumertor<T> : IEnumerator, IEnumerator<T>
{
//迭代索引
private int index;
//迭代器所属的集合对象引用
private List<T> list;
public Enumertor(List<T> container)
{
this.list = container;
this.index = -1;
}
public void Dispose()
{
}
/// <summary>
/// 显示实现IEnumerator的Current属性
/// </summary>
object IEnumerator.Current
{
get
{
return list[index];
}
}
/// <summary>
/// 实现IEnumerator<T>的Current属性
/// </summary>
public T Current
{
get
{
return list[index];
}
}
/// <summary>
/// 迭代器指示到下一个数据位置
/// </summary>
/// <returns></returns>
public bool MoveNext()
{
if (this.index < list.Count)
{
++this.index;
}
return this.index < list.Count;
}
public void Reset()
{
this.index = -1;
}
}
/// <summary>
/// 保存数据的数组，T类型则体现了泛型的作用。
/// </summary>
private T[] array;
/// <summary>
/// 当前集合的长度
/// </summary>
private int count;
/// <summary>
/// 默认构造函数
/// </summary>
public List()
: this(1)
{
}
public List(int capacity)
{
if (capacity < 0)
{
throw new Exception("集合初始长度不能小于0");
}
if (capacity == 0)
{
capacity = 1;
}
this.array = new T[capacity];
}
/// <summary>
/// 集合长度
/// </summary>
public int Count
{
get
{
return this.count;
}
}
/// <summary>
/// 集合实际长度
/// </summary>
public int Capacity
{
get
{
return this.array.Length;
}
}
/// <summary>
/// 是否固定大小
/// </summary>
public bool IsFixedSize
{
get
{
return false;
}
}
/// <summary>
/// 是否只读
/// </summary>
public bool IsReadOnly
{
get
{
return false;
}
}
/// <summary>
/// 是否可同属性
/// </summary>
public bool IsSynchronized
{
get
{
return false;
}
}
/// <summary>
/// 同步对象
/// </summary>
public object SyncRoot
{
get
{
return null;
}
}
/// <summary>
/// 长度不够时，重新分配长度足够的数组
/// </summary>
/// <returns></returns>
private T[] GetNewArray()
{
return new T[(this.array.Length + 1) * 2];
}
/// <summary>
/// 实现IList<T>Add方法
/// </summary>
/// <param name="value"></param>
public void Add(T value)
{
int newCount = this.count + 1;
if (this.array.Length < newCount)
{
T[] newArray = GetNewArray();
Array.Copy(this.array, newArray, this.count);
this.array = newArray;
}
this.array[this.count] = value;
this.count = newCount;
}
/// <summary>
/// 向集合末尾添加对象
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
int IList.Add(object value)
{
((IList<T>)this).Add((T)value);
return this.count - 1;
}
/// <summary>
/// 实现IList<T>索引器
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
public T this[int index]
{
get
{
if (index < 0 || index >= this.count)
{
throw new ArgumentOutOfRangeException("index");
}
return this.array[index];
}
set
{
if (index < 0 || index >= this.count)
{
throw new ArgumentOutOfRangeException("index");
}
this.array[index] = value;
}
}
/// <summary>
/// 显示实现IList接口的索引器
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
object IList.this[int index]
{
get
{
return ((IList<T>)this)[index];
}
set
{
((IList<T>)this)[index] = (T)value;
}
}
/// <summary>
/// 删除集合中的元素
/// </summary>
/// <param name="index"></param>
/// <param name="count"></param>
public void RemoveRange(int index, int count)
{
if (index < 0)
{
throw new ArgumentOutOfRangeException("index");
}
int removeIndex = index + count;
if (count < 0 || removeIndex > this.count)
{
throw new ArgumentOutOfRangeException("index");
}
Array.Copy(this.array, index + 1, this.array, index + count - 1, this.count - removeIndex);
this.count -= count;
}
/// <summary>
/// 实现IList<T>接口的indexOf方法
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public int IndexOf(T value)
{
int index = 0;
if (value == null)
{
while (index < this.count)
{
if (this.array[index] == null)
{
return index;
}
++index;
}
}
else
{
while (index < this.count)
{
if (value.Equals(this.array[index]))
{
return index;
}
++index;
}
}
return -1;
}
/// <summary>
/// 显示实现IList接口的IndexOf方法
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
int IList.IndexOf(object value)
{
return ((IList<T>)this).IndexOf((T)value);
}
/// <summary>
/// 查找对应数组项
/// </summary>
/// <param name="o"></param>
/// <param name="compar"></param>
/// <returns></returns>
public int IndexOf(object o, IComparer compar)
{
int index = 0;
while (index < this.count)
{
if (compar.Compare(this.array[index], o) == 0)
{
return index;
}
++index;
}
return -1;
}
/// <summary>
/// 实现IList<T>接口的Remove方法
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public bool Remove(T value)
{
int index = this.IndexOf(value);
if (index >= 0)
{
this.RemoveRange(index, 1);
return true;
}
return false;
}
/// <summary>
/// 显示实现IList接口的Remove方法，此处显示实现
/// </summary>
/// <param name="value"></param>
void IList.Remove(object value)
{
((IList<T>)this).Remove((T)value);
}
/// <summary>
/// 从集合指定位置删除对象的引用
/// </summary>
/// <param name="index"></param>
public void RemoveAt(int index)
{
RemoveRange(index, 1);
}
/// <summary>
/// 弹出集合的最后一个元素
/// </summary>
/// <returns></returns>
public object PopBack()
{
object o = this.array[this.count - 1];
RemoveAt(this.count - 1);
return o;
}
/// <summary>
/// 弹出集合第一个对象
/// </summary>
/// <returns></returns>
public object PopFront()
{
object o = this.array[0];
RemoveAt(0);
return o;
}
/// <summary>
/// 实现IList<T>接口的Insert方法
/// </summary>
/// <param name="index"></param>
/// <param name="value"></param>
public void Insert(int index, T value)
{
if (index >= this.count)
{
throw new ArgumentOutOfRangeException("index");
}
int newCount = this.count + 1;
if (this.array.Length < newCount)
{
T[] newArray = GetNewArray();
Array.Copy(this.array, newArray, index);
newArray[index] = value;
Array.Copy(this.array, index, newArray, index + 1, this.count - index);
this.array = newArray;
}
else
{
Array.Copy(this.array, index, this.array, index + 1, this.count - index);
this.array[index] = value;
}
this.count = newCount;
}
/// <summary>
/// 显示实现IList接口的Insert方法
/// </summary>
/// <param name="index"></param>
/// <param name="value"></param>
void IList.Insert(int index, object value)
{
((IList<T>)this).Insert(index, (T)value);
}
/// <summary>
/// 实现IList<T>接口的Contains方法
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public bool Contains(T value)
{
return this.IndexOf(value) >= 0;
}
/// <summary>
/// 显示实现IList<T>接口的Contains方法
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
bool IList.Contains(object value)
{
return ((IList<T>)this).IndexOf((T)value) >= 0;
}
/// <summary>
/// 将集合压缩为实际长度
/// </summary>
public void TrimToSize()
{
if (this.array.Length > this.count)
{
T[] newArray = null;
if (this.count > 0)
{
newArray = new T[this.count];
Array.Copy(this.array, newArray, this.count);
}
else
{
newArray = new T[1];
}
this.array = newArray;
}
}
/// <summary>
/// 清空集合
/// </summary>
public void Clear()
{
this.count = 0;
}
/// <summary>
/// 实现IEnumerable接口的GetEnumerator方法
/// </summary>
/// <returns></returns>
public IEnumerator<T> GetEnumerator()
{
Enumertor<T> ator = new Enumertor<T>(this);
return ator;
}
/// <summary>
/// 显示实现IEnumerable接口的GetEnumerator方法
/// </summary>
/// <returns></returns>
IEnumerator IEnumerable.GetEnumerator()
{
return ((IEnumerable<T>)this).GetEnumerator();
}
/// <summary>
/// 实现ICollection<T>接口的CopyTo方法
/// </summary>
/// <param name="array"></param>
/// <param name="index"></param>
public void CopyTo(T[] array, int index)
{
Array.Copy(this.array, 0, array, index, this.count);
}
/// <summary>
/// 显示实现实现ICollection<T>接口的CopyTo方法
/// </summary>
/// <param name="array"></param>
/// <param name="index"></param>
void ICollection.CopyTo(Array array, int index)
{
Array.Copy(this.array, 0, array, index, this.count);
}
}Call:
static void Main(string[] args)
{
//由于已经指定了int，因此加入值类型不会有装箱拆箱操作。
List<int> tList = new List<int>();
tList.Add(25);
tList.Add(30);
foreach (int n in tList)
{
Console.WriteLine(n);
}
Console.ReadLine();
}以上は C# の基礎知識の内容です 基礎知識 (17) ILiest インターフェイス - ジェネリックス 関連内容については、PHP 中国語 Web サイト (www.php.cn) をご覧ください。 ）！
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