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ArrayList Class

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Implements the IList interface using an array whose size is dynamically increased as required.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)
<SerializableAttribute> _
Public Class ArrayList _
	Implements IList, ICollection, IEnumerable, ICloneable

The ArrayList type exposes the following members.

  Name Description
Public method ArrayList Initializes a new instance of the ArrayList class that is empty and has the default initial capacity.
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  Name Description
Public property Capacity Gets or sets the number of elements that the ArrayList can contain.
Public property Count Gets the number of elements actually contained in the ArrayList.
Public property IsFixedSize Gets a value indicating whether the ArrayList has a fixed size.
Public property IsReadOnly Gets a value indicating whether the ArrayList is read-only.
Public property IsSynchronized Gets a value indicating whether access to the ArrayList is synchronized (thread safe).
Public property Item Gets or sets the element at the specified index.
Public property SyncRoot Gets an object that can be used to synchronize access to the ArrayList.
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  Name Description
Public method Add Adds an object to the end of the ArrayList.
Public method BinarySearch Searches the entire sorted ArrayList for an element using the specified comparer and returns the zero-based index of the element.
Public method Clear Removes all elements from the ArrayList.
Public method Clone Creates a shallow copy of the ArrayList.
Public method Contains Determines whether an element is in the ArrayList.
Public method CopyTo(Array) Copies the entire ArrayList to a compatible one-dimensional Array, starting at the beginning of the target array.
Public method CopyTo(Array, Int32) Copies the entire ArrayList to a compatible one-dimensional Array, starting at the specified index of the target array.
Public method Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected method Finalize Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method GetEnumerator Returns an enumerator for the entire ArrayList.
Public method GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
Public method GetType Gets the Type of the current instance. (Inherited from Object.)
Public method IndexOf(Object) Searches for the specified Object and returns the zero-based index of the first occurrence within the entire ArrayList.
Public method IndexOf(Object, Int32) Searches for the specified Object and returns the zero-based index of the first occurrence within the range of elements in the ArrayList that extends from the specified index to the last element.
Public method IndexOf(Object, Int32, Int32) Searches for the specified Object and returns the zero-based index of the first occurrence within the range of elements in the ArrayList that starts at the specified index and contains the specified number of elements.
Public method Insert Inserts an element into the ArrayList at the specified index.
Protected method MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
Public method Remove Removes the first occurrence of a specific object from the ArrayList.
Public method RemoveAt Removes the element at the specified index of the ArrayList.
Public method ToArray()()()() Copies the elements of the ArrayList to a new Object array.
Public method ToArray(Type) Copies the elements of the ArrayList to a new array of the specified element type.
Public method ToString Returns a string that represents the current object. (Inherited from Object.)
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The ArrayList is not guaranteed to be sorted. You must sort the ArrayList prior to performing operations (such as BinarySearch) that require the ArrayList to be sorted.

The capacity of a ArrayList is the number of elements the ArrayList can hold. As elements are added to an ArrayList, the capacity is automatically increased as required through reallocation. The capacity can be decreased by calling TrimToSize or by setting the Capacity property explicitly.

For very large ArrayList objects, you can increase the maximum capacity to 2 billion elements on a 64-bit system by setting the enabled attribute of the gcAllowVeryLargeObjects configuration element to true in the run-time environment.

Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.

The ArrayList collection accepts nullNothingnullptrunita null reference (Nothing in Visual Basic) as a valid value, allows duplicate elements.

Using multidimensional arrays as elements in an ArrayList collection is not supported.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.