Csharp/CSharp Tutorial/Data Structure/ArrayList

ArrayList: AddRange

<source lang="csharp">using System; using System.Collections; using System.Collections.Specialized; class MyClass{

  public string MyName="";   

} class MainClass {

 static void Main(string[] args)
 {
   ArrayList classList = new ArrayList();
   classList.AddRange(new MyClass[] { new MyClass(), 
                                          new MyClass(), 
                                          new MyClass()});
   Console.WriteLine("Items in List: {0}", classList.Count);
   // Print out current values. 
   foreach(MyClass c in classList)
   {
     Console.WriteLine("MyClass name: {0}", c.MyName);  
   }
 }

}</source>

Items in List: 3
MyClass name:
MyClass name:
MyClass name:

ArrayList Query

<source lang="csharp">using System; using System.Collections; using System.ruponentModel;

   public class Product
   {
       string name;
       public string Name
       {
           get { return name; }
       }
       decimal price;
       public decimal Price
       {
           get { return price; }
       }
       public Product(string name, decimal price)
       {
           this.name = name;
           this.price = price;
       }
       public static ArrayList GetSampleProducts()
       {
           ArrayList list = new ArrayList();
           list.Add(new Product("C", 9.99m));
           list.Add(new Product("A", 1.99m));
           list.Add(new Product("F", 2.99m));
           list.Add(new Product("S", 3.99m));
           return list;
       }
       public override string ToString()
       {
           return string.Format("{0}: {1}", name, price);
       }
   }
   class ArrayListSort
   {
       class ProductNameComparer : IComparer
       {
           public int Compare(object x, object y)
           {
               Product first = (Product)x;
               Product second = (Product)y;
               return first.Name.rupareTo(second.Name);
           }
       }
       static void Main()
       {
           ArrayList products = Product.GetSampleProducts();
           products.Sort(new ProductNameComparer());
           foreach (Product product in products)
           {
               Console.WriteLine(product);
           }
       }
   }</source>

Box ints into ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 static void Main(string[] args)
 {    
   ArrayList myInts = new ArrayList();
   myInts.Add(8);
   myInts.Add(3);
   myInts.Add(9);
   // Unbox first item.
   int firstItem = (int)myInts[0];
   // Another boxing operation!
   Console.WriteLine("First item is {0}", firstItem);
 }

}</source>

First item is 8

Capacity and element count

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList al = new ArrayList(); 
    
   Console.WriteLine("Adding 6 elements"); 
   al.Add("C"); 
   al.Add("A"); 
   al.Add("E"); 
   al.Add("B"); 
   al.Add("D"); 
   al.Add("F"); 

   Console.WriteLine("Add enough elements to force ArrayList to grow. Adding 20 more elements"); 
   
   for(int i=0; i < 20; i++) 
     al.Add((char)("a" + i)); 
   Console.WriteLine("Current capacity: " + 
                      al.Capacity); 
   Console.WriteLine("Number of elements after adding 20: " + 
                      al.Count); 
   Console.Write("Contents: "); 
   foreach(char c in al) 
     Console.Write(c + " "); 
   Console.WriteLine("\n"); 
 }

}</source>

Adding 6 elements
Add enough elements to force ArrayList to grow. Adding 20 more elements
Current capacity: 32
Number of elements after adding 20: 26
Contents: C A E B D F a b c d e f g h i j k l m n o p q r s t

Change contents using array indexing

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList al = new ArrayList(); 
    
   Console.WriteLine("Adding 6 elements"); 
   // Add elements to the array list 
   al.Add("C"); 
   al.Add("A"); 
   al.Add("E"); 
   al.Add("B"); 
   al.Add("D"); 
   al.Add("F"); 

   // 
   Console.WriteLine("Change first three elements"); 
   al[0] = "X"; 
   al[1] = "Y"; 
   al[2] = "Z"; 
   Console.Write("Contents: "); 
   foreach(char c in al) 
     Console.Write(c + " "); 
   Console.WriteLine(); 
 } 

}</source>

Adding 6 elements
Change first three elements
Contents: X Y Z B D F

Clear an ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 static void Main(string[] args)
 {
   ArrayList a = new ArrayList(10);
   int x = 0;
   a.Add( ++x);
   a.Add( ++x);
   a.Add( ++x);
   a.Add( ++x);
   a.Remove(x);
   
   a.RemoveAt(0);
   a.Clear();
 }

}</source>

Create a string array and use the ICollection.CopyTo method to copy the contents of the ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

   public static void Main(string[] args)
   {
       // Create a new ArrayList and populate it.
       ArrayList list = new ArrayList(5);
       list.Add("B");
       list.Add("G");
       list.Add("J");
       list.Add("S");
       list.Add("M");
       
       string[] array1 = new string[list.Count];
       list.CopyTo(array1, 0);
       Console.WriteLine("Array 1:");
       foreach (string s in array1) 
       { 
           Console.WriteLine("\t{0}",s); 
       }
   
   }

}</source>

Array 1:
        B
        G
        J
        S
        M

Filter int from ArrayList

<source lang="csharp">using System; using System.Collections.Generic; using System.Text; using System.Xml.Linq; using System.Linq; using System.Collections;

   class Car
   {
       public string PetName;
       public string Color;
       public int Speed;
       public string Make;
   }
   class Program
   {
       static void Main(string[] args)
       {
           ArrayList myStuff = new ArrayList();
           myStuff.AddRange(new object[] { 10, 400, 8, false, new Car(), "string data" });
           IEnumerable<int> myInts = myStuff.OfType<int>();
           
           foreach (int i in myInts)
           {
               Console.WriteLine("Int value: {0}", i);
           }
       }
   }</source>

Get an enumerator using the GetEnumerator() method and use it to read the elements in ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);
   Console.WriteLine("Using the GetEnumerator() method to get an enumerator");
   IEnumerator myEnumerator = myArrayList.GetEnumerator();
   while (myEnumerator.MoveNext())
   {
     Console.WriteLine("myEnumerator.Current = " + myEnumerator.Current);
   }
 }

}</source>

Get the number of elements

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList al = new ArrayList(); 
    
   Console.WriteLine("Initial number of elements: " + al.Count); 

   Console.WriteLine("Adding 6 elements"); 
   // Add elements to the array list 
   al.Add("C"); 
   al.Add("A"); 
   al.Add("E"); 
   al.Add("B"); 
   al.Add("D"); 
   al.Add("F"); 

   Console.WriteLine("Number of elements: " + al.Count); 
 }

}</source>

Initial number of elements: 0
Adding 6 elements
Number of elements: 6

Insert(), AddRange(), and InsertRange() methods

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   
   myArrayList.Add("is");
   myArrayList.Insert(1, "is");
   string[] myStringArray = {"a", "test"};
   myArrayList.AddRange(myStringArray);
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.InsertRange(myArrayList.Count, anotherStringArray);
   DisplayArrayList("myArrayList", myArrayList);
 }
 public static void DisplayArrayList(string arrayListName, ArrayList myArrayList)
 {
   for (int i = 0; i < myArrayList.Count; i++){
     Console.WriteLine(arrayListName + "[" + i + "] = " +
       myArrayList[i]);
   }
 }
 

}</source>

myArrayList[0] = is
myArrayList[1] = is
myArrayList[2] = a
myArrayList[3] = test
myArrayList[4] = Here"s
myArrayList[5] = some
myArrayList[6] = more
myArrayList[7] = text

Insert and remove at specific index

<source lang="csharp">using System; using System.Collections; class MainClass {

 static void Main(string[] args)
 {
   ArrayList a = new ArrayList(10);
   int x = 0;
   a.Add( ++x);
   a.Add( ++x);
   a.Add( ++x);

   a.Remove(x);
   
   a.RemoveAt(0);
 }

}</source>

Insert item to ArrayList by index

<source lang="csharp">using System; using System.Collections; using System.Collections.Specialized; class MyClass{

  public string MyName="";   

} class MainClass {

 static void Main(string[] args)
 {
   ArrayList classList = new ArrayList();
   classList.AddRange(new MyClass[] { new MyClass(), 
                                          new MyClass(), 
                                          new MyClass()});
   Console.WriteLine("Items in List: {0}", classList.Count);
   classList.Insert(2, new MyClass());
   Console.WriteLine("Items in classList: {0}", classList.Count);
   // Print out current values. 
   foreach(MyClass c in classList)
   {
     Console.WriteLine("MyClass name: {0}", c.MyName);  
   }
 }

}</source>

Items in List: 3
Items in classList: 4
MyClass name:
MyClass name:
MyClass name:
MyClass name:

IsFixedSize and IsReadOnly properties

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   
   Console.WriteLine("myArrayList.IsFixedSize = " + myArrayList.IsFixedSize);
   Console.WriteLine("myArrayList.IsReadOnly = " + myArrayList.IsReadOnly);
 }

}</source>

myArrayList.IsFixedSize = False
myArrayList.IsReadOnly = False

Make an ArrayList Synchronized

<source lang="csharp">using System; using System.Collections; class MainClass {

 static void Main(string[] args)
 {
   ArrayList a = new ArrayList(10);
   ArrayList.Synchronized(a);
 }

}</source>

Re-enumerate the list

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList list = new ArrayList(1); 

   for(int i=0; i < 10; i++) 
     list.Add(i); 

   IEnumerator etr = list.GetEnumerator(); 
   while(etr.MoveNext())  
     Console.Write(etr.Current + " "); 

   Console.WriteLine(); 

    
   etr.Reset(); 
   while(etr.MoveNext())  
     Console.Write(etr.Current + " "); 

   Console.WriteLine(); 
 } 

}</source>

0 1 2 3 4 5 6 7 8 9
0 1 2 3 4 5 6 7 8 9

Remove element 0, first "text" element, and two elements starting at index 3

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);

   myArrayList.RemoveAt(0);
   myArrayList.Remove("text");
   myArrayList.RemoveRange(3, 2);
   DisplayArrayList("myArrayList", myArrayList);
 }
 public static void DisplayArrayList(string arrayListName, ArrayList myArrayList)
 {
   for (int i = 0; i < myArrayList.Count; i++){
     Console.WriteLine(arrayListName + "[" + i + "] = " +
       myArrayList[i]);
   }
 }

}</source>

Remove elements from ArrayList

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList al = new ArrayList(); 
    
   Console.WriteLine("Adding 6 elements"); 
   // Add elements to the array list 
   al.Add("C"); 
   al.Add("A"); 
   al.Add("E"); 
   al.Add("B"); 
   al.Add("D"); 
   al.Add("F"); 

   Console.WriteLine("Removing 2 elements"); 
   // Remove elements from the array list. 
   al.Remove("F"); 
   al.Remove("A"); 

   Console.WriteLine("Number of elements: " + 
                      al.Count); 
 }

}</source>

Adding 6 elements
Removing 2 elements
Number of elements: 4

Sort and search an ArrayList

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   // create an array list 
   ArrayList al = new ArrayList(); 
    
   // Add elements to the array list 
   al.Add(155); 
   al.Add(413); 
   al.Add(-41); 
   al.Add(818); 
   al.Add(31); 
   al.Add(191); 

   Console.Write("Original contents: "); 
   foreach(int i in al) 
     Console.Write(i + " "); 
   Console.WriteLine("\n"); 

   // Sort 
   al.Sort(); 

   // Use foreach loop to display the list. 
   Console.Write("Contents after sorting: "); 
   foreach(int i in al) 
     Console.Write(i + " "); 
   Console.WriteLine("\n"); 

   Console.WriteLine("Index of 413 is " + al.BinarySearch(413)); 
 } 

}</source>

Original contents: 155 413 -41 818 31 191
Contents after sorting: -41 31 155 191 413 818
Index of 413 is 4

Use ArrayList copy constructor

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("This");
   myArrayList.Add("is");
   myArrayList.Add("a");
   myArrayList.Add("test");
   ArrayList anotherArrayList = new ArrayList(myArrayList);
   Console.WriteLine(anotherArrayList);
 }

}</source>

Use ArrayList.ToArray to create an object array from the contents of the collection

<source lang="csharp">using System; using System.Collections; class MainClass {

   public static void Main(string[] args)
   {
       // Create a new ArrayList and populate it.
       ArrayList list = new ArrayList(5);
       list.Add("B");
       list.Add("G");
       list.Add("J");
       list.Add("S");
       list.Add("M");
       object[] array2 = list.ToArray();
       Console.WriteLine("Array 2:");
       foreach (string s in array2) 
       {
           Console.WriteLine("\t{0}", s);
       }
   
   }

}</source>

Array 2:
        B
        G
        J
        S
        M

Use enumerator to access list

<source lang="csharp">using System; using System.Collections;

class MainClass {

 public static void Main() { 
   ArrayList list = new ArrayList(1); 

   for(int i=0; i < 10; i++) 
     list.Add(i); 

   IEnumerator etr = list.GetEnumerator(); 
   while(etr.MoveNext())  
     Console.Write(etr.Current + " "); 

   Console.WriteLine(); 

 } 

}</source>

0 1 2 3 4 5 6 7 8 9

Use the Contains() method to determine if the string "text" is in the ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);

   if (myArrayList.Contains("text"))
   {
     int index = myArrayList.IndexOf("text");
     Console.WriteLine("myArrayList does contain the word "text"");
     Console.WriteLine(""text" first occurs at index " + index);
     index = myArrayList.LastIndexOf("text");
     Console.WriteLine(""text" last occurs at index " + index);
   }
 }

}</source>

Use the IndexOf() and LastIndexOf() methods to display the first and last occurrence

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);

   if (myArrayList.Contains("text"))
   {
     int index = myArrayList.IndexOf("text");
     Console.WriteLine("myArrayList does contain the word "text"");
     Console.WriteLine(""text" first occurs at index " + index);
     index = myArrayList.LastIndexOf("text");
     Console.WriteLine(""text" last occurs at index " + index);
   }
 }

}</source>

Use the Reset() method and access the first row again using MoveNext()

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);
   Console.WriteLine("Using the GetEnumerator() method to get an enumerator");
   IEnumerator myEnumerator = myArrayList.GetEnumerator();
   while (myEnumerator.MoveNext())
   {
     Console.WriteLine("myEnumerator.Current = " + myEnumerator.Current);
   }
   myEnumerator.Reset();
   myEnumerator.MoveNext();
   Console.WriteLine("myEnumerator.Current = " + myEnumerator.Current);
   
 }

}</source>

Use the Reverse() method to reverse myArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);
   myArrayList.Reverse();
   DisplayArrayList("myArrayList", myArrayList);
 }
 public static void DisplayArrayList(string arrayListName, ArrayList myArrayList)
 {
   for (int i = 0; i < myArrayList.Count; i++){
     Console.WriteLine(arrayListName + "[" + i + "] = " +
       myArrayList[i]);
   }
 }

}</source>

Use the SetRange() method to copy the elements from anotherStringArray to myArrayList, starting at index 0

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);

   DisplayArrayList("myArrayList", myArrayList);
 }
 public static void DisplayArrayList(string arrayListName, ArrayList myArrayList)
 {
   for (int i = 0; i < myArrayList.Count; i++){
     Console.WriteLine(arrayListName + "[" + i + "] = " +
       myArrayList[i]);
   }
 }
 

}</source>

Using the GetRange() method to get two elements from myArrayList, starting at index 1

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);
   ArrayList anotherArrayList = myArrayList.GetRange(1, 2);
   DisplayArrayList("anotherArrayList", anotherArrayList);
 }
 public static void DisplayArrayList(string arrayListName, ArrayList myArrayList)
 {
   for (int i = 0; i < myArrayList.Count; i++){
     Console.WriteLine(arrayListName + "[" + i + "] = " +
       myArrayList[i]);
   }
 }

}</source>

Using the TrimToSize() method to reduce the capacity of ArrayList

<source lang="csharp">using System; using System.Collections; class MainClass {

 public static void Main()
 {
   ArrayList myArrayList = new ArrayList();
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   myArrayList.Add("A");
   
   string[] anotherStringArray = {"Here"s", "some", "more", "text"};
   myArrayList.SetRange(0, anotherStringArray);
   myArrayList.TrimToSize();
   Console.WriteLine("myArrayList.Capacity = " + myArrayList.Capacity);
 }

}</source>