Collection
Set
or group of records which makes one meaningful unit: In fetch and
modification progress we need appropriate container to store them
temporary in it. Appropriate container depends on: 1. Our action which
we want to do on data ( just read, do modification such as insert,
delete, etc ) 2. Number of records which should be transfer
Array
1.
Fixed Length -> difficult to change the nember of count 2. Type Safe
-> you determin its type at coding process (it has better
performance due to do not consume time at run time to spesific type
countainer ) 3. Use “for” keyword to fill and iterate through array
Array is faster than Arraylist because it is fixed sized and srong type,
so it needs less memory due to its data type and dimenssion is
determined
//It is obvious that strArray is //1. string --> Strongly Type //2. Sized=10 --> Fixed Size string[] strArray = new string[10]; for (int i = 0; i < 10; i++) { if (strArray[i]==null) { strArray[i] = (i+1).ToString(); } } this.ListBoxArray.DataSource = null; this.ListBoxArray.Items.Clear(); this.ListBoxArray.DataSource = strArray; this.ListBoxArray.DataBind();
ArrayList
1.
It does not have spesific length -> It is possible to grow data , it
is good feature because of at the first we are not likely to sure about
length of collection 2. Arraylist does not have any spesific type and
it will be determined at run time, its adbantage is when you are not
sure about type of data untill in run time user detemines it, and its
disadvantage is to reduce performance by consuming time , so use it just
when you need it it is like var or object 3. Use “foreach” keyword for
iterate through it
public class Product { public Product() { } public Product(string Code, string Name) { _Code = Code; _Name = Name; } public string _Code {get; set;} public string _Name { get; set; } }
ArrayList can accept string , integer and decimal at the same time
//It is NOT obvious that strArrayList is 1. string? int? object? decimal? --> NOT Strongly Type // 2. Sized=10? 20? 100? -->NOT Fixed Size // Namespace: System.Collections System.Collections.ArrayList strArrayList = new System.Collections.ArrayList(); //System.Linq.IQueryable type of data is not specific runtime defered support strArrayList.Add("Mahsa"); // "Mahsa": is string strArrayList.Add(1); // 1 : is integer strArrayList.Add(0.89); // 0.89: is decimal this.ListBoxArrayList.DataSource = null; this.ListBoxArrayList.Items.Clear(); this.ListBoxArrayList.DataSource = strArrayList; this.ListBoxArrayList.DataBind(); System.Text.StringBuilder str= new System.Text.StringBuilder(); foreach (var item in strArrayList) { str.Append(" , "+item); } this.lblArrayList.Text = str.ToString(); //Below is old way to fill obj from product , in Arraylist you need to create more than one instance // Product objProduct = new Product(); // objProduct.Code = "1001"; // objProduct.Name = "Chair"; //It is NOT obvious that strArrayList is //1. string? int? object? decimal? OR OBJECT?? --> NOT Strongly Type //2. Sized=10? 20? 100? -->NOT Fixed Size // Namespace: System.Collections System.Collections.ArrayList objArrayList = new System.Collections.ArrayList(); objArrayList.Add(new Product("1001", "Chair")); objArrayList.Add(new Product("1002", "Sofa")); objArrayList.Add(new Product("1003", "Carpet")); this.DropDownListArrayListObject.DataSource = null; this.DropDownListArrayListObject.Items.Clear(); this.DropDownListArrayListObject.DataSource = objArrayList; //* Finding among Object of Array List is difficult , you have to find your specific item by index Product objTemp = (Product)objArrayList[0]; objArrayList.Remove(objTemp); //* this.DropDownListArrayListObject.DataTextField = "_Name"; this.DropDownListArrayListObject.DataValueField = "_Code"; this.DropDownListArrayListObject.DataBind(); this.GridViewArrayListObject.DataSource = objArrayList; this.GridViewArrayListObject.DataBind();
HashTable
//It is NOT obvious that strArrayList is //1. string? int? object? decimal? OR OBJECT?? --> NOT Strongly Type //2. Sized=10? 20? 100? -->NOT Fixed Size // Namespace: System.Collections //Hashtable solve the problem in Arraylist when we are looking for specific item //Hashtable dedicate a key for each item, then finding item is easier and faster System.Collections.Hashtable objHashTable = new System.Collections.Hashtable(); objHashTable.Add("1001","Chair"); objHashTable.Add("1002", "Sofa"); objHashTable.Add("1003", "Carpet"); this.DropDownListHashTable.DataSource = null; this.DropDownListHashTable.Items.Clear(); this.DropDownListHashTable.DataSource = objHashTable; //* finding item is easier you just need to point to it by call its key objHashTable.Remove("1002"); //* this.DropDownListHashTable.DataTextField = "Value"; this.DropDownListHashTable.DataValueField = "Key"; this.DropDownListHashTable.DataBind();
Stack
Stack - Push
//Stack is LIFO: Last in First Out System.Collections.Stack objStackPush = new System.Collections.Stack(); //By Push method you can insert item at the top of the stack objStackPush.Push("Mahsa"); objStackPush.Push("Hassankashi"); this.lblPop.Text = ""; this.ListBoxStack.DataSource = objStackPush.ToArray(); this.ListBoxStack.DataBind();
Stack - Pop
System.Collections.Stack objStackPop = new System.Collections.Stack(); objStackPop.Push("Mahsa"); objStackPop.Push("Hassankashi"); //By Pop method you can remove item from the top of the stack --> Last in First in this.lblPop.Text = objStackPop.Pop().ToString(); this.ListBoxStack.DataSource = objStackPop.ToArray(); this.ListBoxStack.DataBind();
Queue
Queue - Enqueue
//Queue is FIFO: First in First Out System.Collections.Queue objQueue = new System.Collections.Queue(); //By Enqueue method you can insert item at the END of the Queue objQueue.Enqueue("Mahsa"); objQueue.Enqueue("Hassankashi"); objQueue.Enqueue("Cosmic"); objQueue.Enqueue("Verse"); this.lblQueue.Text = ""; this.ListBoxQueue.DataSource = objQueue.ToArray(); this.ListBoxQueue.DataBind();
Queue - Dequeue
System.Collections.Queue objQueue = new System.Collections.Queue(); objQueue.Enqueue("Mahsa"); objQueue.Enqueue("Hassankashi"); objQueue.Enqueue("Cosmic"); objQueue.Enqueue("Verse"); //By Dequeue method you can remove item from the BEGINING of the Queue --> First in First out FIFO this.lblQueue.Text=objQueue.Dequeue().ToString(); this.ListBoxQueue.DataSource = objQueue.ToArray(); this.ListBoxQueue.DataBind();
List
Why
we needList? 1. List does not have spesific length à It is possible to
have data without knowing its size , it is good feature because of at
the first we are not likely to sure about length of collection. 2. List
has Spesific type so it is strong type, therfore it has better
perfomance and high speed in comparison with ArrayList and reduce
unwanted error in compile time. 3. Use “foreach” keyword for iterate
through it.
//Like Array is Strong Type //Like ArrayList with No Dimension System.Collections.Generic.List<string> strList = new List<string>(); strList.Add("Mahsa"); strList.Add("Hassankashi"); strList.Add("Cosmic"); strList.Add("Verse"); this.ListBoxListGeneric.DataSource = strList; this.ListBoxListGeneric.DataBind(); System.Text.StringBuilder str = new System.Text.StringBuilder(); foreach (var item in strList) { str.Append(" , " + item); } this.lblList.Text = str.ToString();
IList
Why
we need IList? Ilist is an interface of list (does everything that List
does) and to observe polymorphism in order to decouple and control on
add or remove method that implement on the client side, everything else
are similar to List. Whenever we want to change on some operation
“IList” allow us to do that easily with at least changing in the whole
of codes. Ilist can not be instantiate from Ilist , so it should be
instantiate from List
System.Collections.Generic.IList<string> strIList = new List<string>();
Difference between Abstract and Interface
1.Abstract inherit from just one class but Interface implements from one or more interfaces
2.Abstract can have non concrete method (expand method) but you have to define just signature inside interface
3.Inside Abstract class you can define variable and value but you are not allowed to define variable inside interface
4.An abstract class can have constructor but inside interface you are not allowed to define constructor
5.You
can write scope for member of interface, red ones donot allow but blue
one allow Ilist is an interface and as I mentioned that how a class
cannot be driven from two class it just can be driven from only one
class, so whenever you want to drive from two class it is not possible
to inherit from two abstract class but it is possible to drive from one
class and another one Ilist as interface Later in future you decide add
some features on your class and inherit it from another class So because
of this reason we always prefer to use interface of collection so that
if you want to change your code and enhance its abilities it is possible
to grow it On the otherhand interface keeps your program extensible and
Decouple: The classes are independent from each other error, exeption
and failur will happen rarly in future changing code Polymorphism: When
you are using interface you absolutly observe and do polymorphism and
oop it means encapsulate your designer Interface means a point or a node
to join two part to eachother it means making low dependency from two
part and make a joint section to make felxible chang in future
//Ilist can not be instantiate from Ilist , so it should be instantiate from List System.Collections.Generic.IList<string> strIList = new List<string>(); strIList.Add("Mahsa"); strIList.Add("Hassankashi"); strIList.Add("Cosmic"); strIList.Add("Verse"); this.ListBoxListGeneric.DataSource = strIList; this.ListBoxListGeneric.DataBind(); System.Text.StringBuilder str = new System.Text.StringBuilder(); foreach (var item in strIList) { str.Append(" , " + item); } this.lblList.Text = str.ToString();
IList
is similar to List but with this difference that we prefer to use
INTERFACE instead of abstract in programming because future changing is
easy
IEnumerable
IEnumerable
is suitable just for iterate through collection and you can not modify
(Add or Remove) it IEnumerable bring ALL data from server to client then
filter them, assume that you have a lot of records so IEnumerable puts
overhead on your memory
//IEnumerable can not be instantiate from Enumerable , so it should be instantiate from List System.Collections.Generic.IEnumerable<Employee> empIEnumerable = new List<Employee> { new Employee { ID = 1001, Name="Mahsa"}, new Employee { ID = 1002, Name = "Hassankashi" }, new Employee { ID = 1003, Name = "CosmicVerse" }, new Employee { ID = 1004, Name = "Technical" } }; this.GridViewIEnumerable.DataSource = empIEnumerable; this.GridViewIEnumerable.DataBind(); System.Text.StringBuilder str = new System.Text.StringBuilder(); foreach (Employee item in empIEnumerable) { str.Append(" , " + item.ID +"-"+item.Name); } this.lblIEnumerable.Text = str.ToString();
IQueryable
Follow "Entity Framework DatabaseFirst" from this article for making DBContext
DataAccessEntities ctx = new DataAccessEntities(); var ctx = new DataAccessEntities();
//Difference between IQueryable and IEnumerable //You can instantiate IEnumerable from List IEnumerable<Employee> queryIEnumerable = new List<Employee>() ; //Bring ALL records from server --> to client then filter collection queryIEnumerable = (from m in ctx.Employees where m.ID == 1 select m).ToList(); //You can not instantiate IQueryable IQueryable<Employee> queryIQueryable=null; //Bring just ONE record from server --> to client queryIQueryable = (from m in ctx.Employees where m.ID == 1 select m); this.GridViewIQueryable.DataSource = queryIQueryable.ToList(); this.GridViewIQueryable.DataBind();
ICollection
//IList {indexer and Modify} vs ICollection {randomly and Modify}
//Collection can not be instantiate from ICollection , so it should be instantiate from List
System.Collections.Generic.ICollection<string> strICollection = new List<string>();
strICollection.Add("Mahsa");
strICollection.Add("Hassankashi");
//**Countable
int ICollectionCount=strICollection.Count;
this.ListBoxICollection.DataSource = strICollection;
this.ListBoxICollection.DataBind();
System.Text.StringBuilder str = new System.Text.StringBuilder();
foreach (var item in strICollection)
{
str.Append(" , " + item);
}
this.lblICollection.Text = str.ToString();
//***IList
System.Collections.Generic.IList<Employee> objIList = new List<Employee>();
objIList = (from m in ctx.Employees
select m).ToList();
Employee obj = objIList.Where(i => i.Name == "Sara").FirstOrDefault();
int indexofSara= objIList.IndexOf(obj);
int cIList = objIList.Count;
//***ICollection
System.Collections.Generic.ICollection<Employee> objICollection = new List<Employee>();
objICollection = (from m in ctx.Employees
select m).ToList();
Employee objIC = objICollection.Where(i => i.Name == "Sara").FirstOrDefault();
//You can not get index of object , if you clear comment from below code appears error
// int indexofSaraICollection = objIC.IndexOf(objIC);
int cICollection = objICollection.Count;
Dictionary
//Dictionary can instantiate from Dictionary , Dictionary is similar to Hashtable, //Dictionary is GENERIC but Hashtable is NON GENERIC //Such Hashtable you can find object by its key System.Collections.Generic.Dictionary<int, string=""> objDictionary = new Dictionary<int, string="">(); objDictionary.Add(1001, "Mahsa"); objDictionary.Add(1002, "Hassankashi"); objDictionary.Add(1003, "Cosmicverse"); string str = objDictionary[1002]; this.ListBoxDictionary.DataSource = objDictionary; this.ListBoxDictionary.DataBind();</int,></int,>
Source collected from Codeproject.com
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