System.Collections.ReadOnlyCollectionBase Class

Summary

Provides the abstract base class for a strongly typed read-only collection.

C# Syntax:

[Serializable] public abstract class ReadOnlyCollectionBase : ICollection, IEnumerable

Public static (non-instance) members of this type are safe for multithreaded operations. Instance members are not guaranteed to be thread-safe.

This implementation does not provide a synchronized (thread-safe) wrapper for a ReadOnlyCollectionBase, but derived classes can create their own synchronized versions of the ReadOnlyCollectionBase using the ReadOnlyCollectionBase.System.Collections.ICollection.SyncRoot property.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads could still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

A ReadOnlyCollectionBase instance is always read-only. See CollectionBase for a modifiable version of this class.

Notes to implementors:

This base class is provided to make it easier for implementers to create a strongly typed read-only custom collection. Implementers should extend this base class instead of creating their own.

Members of this base class are protected and are intended to be used through a derived class only.

System.Collections Namespace | ArrayList | CollectionBase

System.Collections.ReadOnlyCollectionBase Member List:

Public Properties

Count

Read-only Gets the number of elements contained in the ReadOnlyCollectionBase instance.

Public Methods

Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetEnumerator	Returns an enumerator that can iterate through the ReadOnlyCollectionBase instance.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Constructors

ctor #1

Default constructor. This constructor is called by derived class constructors to initialize state in this type.

Protected Properties

InnerList

Read-only Gets the list of elements contained in the ReadOnlyCollectionBase instance.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Explicit Interface Implementations 

ICollection.CopyTo

Copies the entire ReadOnlyCollectionBase to a compatible one-dimensional Array, starting at the specified index of the target array.

Hierarchy:

• System.Object
• System.Collections.ReadOnlyCollectionBase
  • System.ComponentModel.ComponentCollection

System.Collections.ReadOnlyCollectionBase Member Details

Summary:

Default constructor. This constructor is called by derived class constructors to initialize state in this type.

C# Syntax:

protected ReadOnlyCollectionBase();

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Summary

Gets the number of elements contained in the ReadOnlyCollectionBase instance.

C# Syntax:

public int Count {get;}

Implements:

ICollection.Count

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Summary

Gets the list of elements contained in the ReadOnlyCollectionBase instance.

C# Syntax:

protected ArrayList InnerList {get;}

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~ReadOnlyCollectionBase();

For more information on members inherited from System.Object click on the link above.

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Summary

Returns an enumerator that can iterate through the ReadOnlyCollectionBase instance.

C# Syntax:

public IEnumerator GetEnumerator();

Return Value:

An IEnumerator for the ReadOnlyCollectionBase instance.

Implements:

IEnumerable.GetEnumerator

Enumerators only allow reading the data in the collection. Enumerators cannot be used to modify the underlying collection.

Initially, the enumerator is positioned before the first element in the collection. IEnumerator.Reset also brings the enumerator back to this position. At this position, calling IEnumerator.Current throws an exception. Therefore, you must call IEnumerator.MoveNext to advance the enumerator to the first element of the collection before reading the value of IEnumerator.Current.

IEnumerator.Current returns the same object until either IEnumerator.MoveNext or IEnumerator.Reset is called. IEnumerator.MoveNext sets IEnumerator.Current to the next element.

After the end of the collection is passed, the enumerator is positioned after the last element in the collection, and calling IEnumerator.MoveNext returns false. If the last call to IEnumerator.MoveNext returned false, calling IEnumerator.Current throws an exception. To set IEnumerator.Current to the first element of the collection again, you can call IEnumerator.Reset followed by IEnumerator.MoveNext.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying or deleting elements, the enumerator is irrecoverably invalidated and the next call to IEnumerator.MoveNext or IEnumerator.Reset throws an InvalidOperationException. If the collection is modified between IEnumerator.MoveNext and IEnumerator.Current, IEnumerator.Current will return the element that it is set to, even if the enumerator is already invalidated.

The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads could still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

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Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Summary

Copies the entire ReadOnlyCollectionBase to a compatible one-dimensional Array, starting at the specified index of the target array.

C# Syntax:

void ICollection.CopyTo(    Array array,    int index );

array

The one-dimensional Array that is the destination of the elements copied from ReadOnlyCollectionBase. The Array must have zero-based indexing.

index

The zero-based index in array at which copying begins.

Exceptions

Exception Type	Condition
ArgumentNullException	array is null.
ArgumentOutOfRangeException	index is less than zero.
ArgumentException	array is multidimensional. -or- index is equal to or greater than the length of array. -or- The number of elements in the source ReadOnlyCollectionBase is greater than the available space from index to the end of the destination array.
InvalidCastException	The type of the source ReadOnlyCollectionBase cannot be cast automatically to the type of the destination array.

Implements:

ICollection.CopyTo

The specified array must be of a compatible type.

This method uses Array.Copy to copy the elements.

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Inherited
See base class member description: System.Object.ToString

C# Syntax:

public virtual string ToString();

For more information on members inherited from System.Object click on the link above.

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