How to VB.NET ArrayList

ArrayList is one of the most flexible data structure from VB.NET Collections. With the Array list you can add elements to your array dynamically and it accepts null as a valid value and also allows duplicate elements. Normally Collection class allow you to access an item using either a numeric index or a String key, but ArrayList allows only a numeric index. ArrayList is flexible because we can add items without any size information.

Important functions from ArrayList Object

Add : Add Items in an ArrayList

Insert : Insert Items to a specified position in an ArrayList

Remove : Remove an Item from ArrayList

RemoveAt: remove an item from a specified position

Sort : Sort Items in an ArrayList

How to add Items in an ArrayList ?

Syntax : ArrayList.add(Item) Item : The Item to be add the ArrayList

Dim ItemList As New ArrayList()

ItemList.Add("Item4")

How to Insert Items in an ArrayList ?

Syntax : ArrayList.insert(index,item).
index : The position of the item in an ArrayList.
Item : The Item to be add the ArrayList.

ItemList.Insert(3, "item6")

How to remove an item from arrayList ?

Syntax : ArrayList.Remove(item) Item : The Item to be add the ArrayList

ItemList.Remove("item2")

How to remove an item in a specified position from an ArrayList ?

Syntax : ArrayList.RemoveAt(index) index : the position of an item to remove from an ArrayList

ItemList.RemoveAt(2)

How to sort ArrayList ?

Syntax : ArrayListSort()

From the following Visual Basic source code you can see some important operations from an ArrayList Object

Next : How to use VB.NET HashTable

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Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, 
	ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer
        Dim ItemList As New ArrayList()
        ItemList.Add("Item4")
        ItemList.Add("Item5")
        ItemList.Add("Item2")
        ItemList.Add("Item1")
        ItemList.Add("Item3")
        MsgBox("Shows Added Items")
        For i = 0 To ItemList.Count - 1
            MsgBox(ItemList.Item(i))
        Next
        'insert an item
        ItemList.Insert(3, "Item6")
        'sort itemms in an arraylist
        ItemList.Sort()
        'remove an item
        ItemList.Remove("Item1")
        'remove item from a specified index
        ItemList.RemoveAt(3)
        MsgBox("Shows final Items the ArrayList")
        For i = 0 To ItemList.Count - 1
            MsgBox(ItemList.Item(i))
        Next
    End Sub
End Class

When you execute this program , it add five items in the arraylist and displays using a for loop statement. Then again one more item inserted in the third position , and then sort all items. Next it remove the item1 and also remove the item from the third position . Finally it shows the existing items.

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