HashSet<T>.Enumerator HashSet<T>.Enumerator HashSet<T>.Enumerator HashSet<T>.Enumerator Struct

定義

列舉 HashSet<T> 物件的項目。Enumerates the elements of a HashSet<T> object.

public: value class HashSet<T>::Enumerator : System::Collections::Generic::IEnumerator<T>
[System.Serializable]
public struct HashSet<T>.Enumerator : System.Collections.Generic.IEnumerator<T>
type HashSet<'T>.Enumerator = struct
    interface IEnumerator<'T>
    interface IEnumerator
    interface IDisposable
Public Structure HashSet(Of T).Enumerator
Implements IEnumerator(Of T)

類型參數

T
繼承
HashSet<T>.EnumeratorHashSet<T>.EnumeratorHashSet<T>.EnumeratorHashSet<T>.Enumerator
屬性
實作

備註

foreach陳述式的C#語言 (for each在C++, For Each Visual Basic 中) 會隱藏列舉值的複雜度。The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of enumerators. 因此,建議您使用 foreach,而不要直接使用列舉值。Therefore, using foreach is recommended, instead of directly manipulating the enumerator.

列舉程式可以用來讀取集合中的資料,但是無法用來修改基礎集合。Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.

一開始,列舉程式位在集合中的第一個項目之前。Initially, the enumerator is positioned before the first element in the collection. 在這個位置,Current未定義屬性。At this position, the Current property is undefined. 因此,您必須呼叫MoveNext列舉值前進到第一個項目,再讀取的值集合的方法CurrentTherefore, you must call the MoveNext method to advance the enumerator to the first element of the collection before reading the value of Current.

Current 會傳回相同的物件直到呼叫 MoveNextCurrent returns the same object until MoveNext is called. MoveNext 會將 Current 設定為下一個項目。MoveNext sets Current to the next element.

如果MoveNext集合,也就是列舉值的結尾是否位於集合中的最後一個元素之後的階段和MoveNext傳回falseIf MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. 列舉值位於此位置,後續呼叫MoveNext也會傳回falseWhen the enumerator is at this position, subsequent calls to MoveNext also return false. 如果上次呼叫MoveNext傳回falseCurrent是未定義。If the last call to MoveNext returned false, Current is undefined. 您不能設定Current第一個元素的集合一次; 您必須改為建立新的列舉值物件。You cannot set Current to the first element of the collection again; you must create a new enumerator object instead.

只要集合維持不變,列舉程式就持續有效。An enumerator remains valid as long as the collection remains unchanged. 如果變更集合,例如加入、 修改或刪除元素,列舉值會將永久失效,而且下次呼叫MoveNext或是IEnumerator.Reset就會擲回InvalidOperationExceptionIf changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and the next call to MoveNext or IEnumerator.Reset throws an InvalidOperationException.

列舉程式沒有集合的獨佔存取權,因此,列舉集合內容本質上並不是安全的執行緒程序。The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. 若要確保列舉期間的執行緒安全性,您可以在整個列舉期間鎖定集合。To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. 若要讓多重執行緒能夠存取集合以便進行讀取和寫入,您必須實作自己的同步處理。To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

System.Collections.Generic 命名空間中集合的預設實作未同步處理。Default implementations of collections in the System.Collections.Generic namespace are not synchronized.

屬性

Current Current Current Current

取得位於目前列舉值位置的項目。Gets the element at the current position of the enumerator.

方法

Dispose() Dispose() Dispose() Dispose()

釋放由 HashSet<T>.Enumerator 物件使用的所有資源。Releases all resources used by a HashSet<T>.Enumerator object.

MoveNext() MoveNext() MoveNext() MoveNext()

讓列舉程式前進至 HashSet<T> 集合中的下一個項目。Advances the enumerator to the next element of the HashSet<T> collection.

明確介面實作

IEnumerator.Current IEnumerator.Current IEnumerator.Current IEnumerator.Current

取得位於目前列舉值位置的項目。Gets the element at the current position of the enumerator.

IEnumerator.Reset() IEnumerator.Reset() IEnumerator.Reset() IEnumerator.Reset()

設定列舉值至它的初始位置,這是在集合中第一個項目之前。Sets the enumerator to its initial position, which is before the first element in the collection.

適用於