List<T>.Add(T) Method (System.Collections.Generic) (2023)

Adds an object to the end of the List<T>.

public: virtual void Add(T item);
public void Add (T item);
abstract member Add : 'T -> unitoverride this.Add : 'T -> unit
Public Sub Add (item As T)

Parameters

item
T

The object to be added to the end of the List<T>. The value can be null for reference types.

(Video) List T in C# (Generic Classes)

Implements

Add(T)

(Video) C# - Generic Collection

Examples

The following example demonstrates how to add, remove, and insert a simple business object in a List<T>.

using System;using System.Collections.Generic;// Simple business object. A PartId is used to identify the type of part// but the part name can change.public class Part : IEquatable<Part> { public string PartName { get; set; } public int PartId { get; set; } public override string ToString() { return "ID: " + PartId + " Name: " + PartName; } public override bool Equals(object obj) { if (obj == null) return false; Part objAsPart = obj as Part; if (objAsPart == null) return false; else return Equals(objAsPart); } public override int GetHashCode() { return PartId; } public bool Equals(Part other) { if (other == null) return false; return (this.PartId.Equals(other.PartId)); } // Should also override == and != operators. }public class Example{ public static void Main() { // Create a list of parts. List<Part> parts = new List<Part>(); // Add parts to the list. parts.Add(new Part() { PartName = "crank arm", PartId = 1234 }); parts.Add(new Part() { PartName = "chain ring", PartId = 1334 }); parts.Add(new Part() { PartName = "regular seat", PartId = 1434 }); parts.Add(new Part() { PartName = "banana seat", PartId = 1444 }); parts.Add(new Part() { PartName = "cassette", PartId = 1534 }); parts.Add(new Part() { PartName = "shift lever", PartId = 1634 }); // Write out the parts in the list. This will call the overridden ToString method // in the Part class. Console.WriteLine(); foreach (Part aPart in parts) { Console.WriteLine(aPart); } // Check the list for part #1734. This calls the IEquatable.Equals method // of the Part class, which checks the PartId for equality. Console.WriteLine("\nContains(\"1734\"): {0}", parts.Contains(new Part { PartId = 1734, PartName = "" })); // Insert a new item at position 2. Console.WriteLine("\nInsert(2, \"1834\")"); parts.Insert(2, new Part() { PartName = "brake lever", PartId = 1834 }); //Console.WriteLine(); foreach (Part aPart in parts) { Console.WriteLine(aPart); } Console.WriteLine("\nParts[3]: {0}", parts[3]); Console.WriteLine("\nRemove(\"1534\")"); // This will remove part 1534 even though the PartName is different, // because the Equals method only checks PartId for equality. parts.Remove(new Part() { PartId = 1534, PartName = "cogs" }); Console.WriteLine(); foreach (Part aPart in parts) { Console.WriteLine(aPart); } Console.WriteLine("\nRemoveAt(3)"); // This will remove the part at index 3. parts.RemoveAt(3); Console.WriteLine(); foreach (Part aPart in parts) { Console.WriteLine(aPart); } /* ID: 1234 Name: crank arm ID: 1334 Name: chain ring ID: 1434 Name: regular seat ID: 1444 Name: banana seat ID: 1534 Name: cassette ID: 1634 Name: shift lever Contains("1734"): False Insert(2, "1834") ID: 1234 Name: crank arm ID: 1334 Name: chain ring ID: 1834 Name: brake lever ID: 1434 Name: regular seat ID: 1444 Name: banana seat ID: 1534 Name: cassette ID: 1634 Name: shift lever Parts[3]: ID: 1434 Name: regular seat Remove("1534") ID: 1234 Name: crank arm ID: 1334 Name: chain ring ID: 1834 Name: brake lever ID: 1434 Name: regular seat ID: 1444 Name: banana seat ID: 1634 Name: shift lever RemoveAt(3) ID: 1234 Name: crank arm ID: 1334 Name: chain ring ID: 1834 Name: brake lever ID: 1444 Name: banana seat ID: 1634 Name: shift lever */ }}
Imports System.Collections.Generic' Simple business object. A PartId is used to identify the type of part ' but the part name can change. Public Class Part Implements IEquatable(Of Part) Public Property PartName() As String Get Return m_PartName End Get Set(value As String) m_PartName = Value End Set End Property Private m_PartName As String Public Property PartId() As Integer Get Return m_PartId End Get Set(value As Integer) m_PartId = Value End Set End Property Private m_PartId As Integer Public Overrides Function ToString() As String Return "ID: " & PartId & " Name: " & PartName End Function Public Overrides Function Equals(obj As Object) As Boolean If obj Is Nothing Then Return False End If Dim objAsPart As Part = TryCast(obj, Part) If objAsPart Is Nothing Then Return False Else Return Equals(objAsPart) End If End Function Public Overrides Function GetHashCode() As Integer Return PartId End Function Public Overloads Function Equals(other As Part) As Boolean _ Implements IEquatable(Of Part).Equals If other Is Nothing Then Return False End If Return (Me.PartId.Equals(other.PartId)) End Function ' Should also override == and != operators.End ClassPublic Class Example Public Shared Sub Main() ' Create a list of parts. Dim parts As New List(Of Part)() ' Add parts to the list. parts.Add(New Part() With { _ .PartName = "crank arm", _ .PartId = 1234 _ }) parts.Add(New Part() With { _ .PartName = "chain ring", _ .PartId = 1334 _ }) parts.Add(New Part() With { _ .PartName = "regular seat", _ .PartId = 1434 _ }) parts.Add(New Part() With { _ .PartName = "banana seat", _ .PartId = 1444 _ }) parts.Add(New Part() With { _ .PartName = "cassette", _ .PartId = 1534 _ }) parts.Add(New Part() With { _ .PartName = "shift lever", _ .PartId = 1634 _ }) ' Write out the parts in the list. This will call the overridden ToString method ' in the Part class. Console.WriteLine() For Each aPart As Part In parts Console.WriteLine(aPart) Next ' Check the list for part #1734. This calls the IEquatable.Equals method ' of the Part class, which checks the PartId for equality. Console.WriteLine(vbLf & "Contains(""1734""): {0}", parts.Contains(New Part() With { _ .PartId = 1734, _ .PartName = "" _ })) ' Insert a new item at position 2. Console.WriteLine(vbLf & "Insert(2, ""1834"")") parts.Insert(2, New Part() With { _ .PartName = "brake lever", _ .PartId = 1834 _ }) 'Console.WriteLine(); For Each aPart As Part In parts Console.WriteLine(aPart) Next Console.WriteLine(vbLf & "Parts[3]: {0}", parts(3)) Console.WriteLine(vbLf & "Remove(""1534"")") ' This will remove part 1534 even though the PartName is different, ' because the Equals method only checks PartId for equality. parts.Remove(New Part() With { _ .PartId = 1534, _ .PartName = "cogs" _ }) Console.WriteLine() For Each aPart As Part In parts Console.WriteLine(aPart) Next Console.WriteLine(vbLf & "RemoveAt(3)") ' This will remove part at index 3. parts.RemoveAt(3) Console.WriteLine() For Each aPart As Part In parts Console.WriteLine(aPart) Next End Sub ' ' This example code produces the following output: ' ID: 1234 Name: crank arm ' ID: 1334 Name: chain ring ' ID: 1434 Name: regular seat ' ID: 1444 Name: banana seat ' ID: 1534 Name: cassette ' ID: 1634 Name: shift lever ' ' Contains("1734"): False ' ' Insert(2, "1834") ' ID: 1234 Name: crank arm ' ID: 1334 Name: chain ring ' ID: 1834 Name: brake lever ' ID: 1434 Name: regular seat ' ID: 1444 Name: banana seat ' ID: 1534 Name: cassette ' ID: 1634 Name: shift lever ' ' Parts[3]: ID: 1434 Name: regular seat ' ' Remove("1534") ' ' ID: 1234 Name: crank arm ' ID: 1334 Name: chain ring ' ID: 1834 Name: brake lever ' ID: 1434 Name: regular seat ' ID: 1444 Name: banana seat ' ID: 1634 Name: shift lever ' ' ' RemoveAt(3) ' ' ID: 1234 Name: crank arm ' ID: 1334 Name: chain ring ' ID: 1834 Name: brake lever ' ID: 1444 Name: banana seat ' ID: 1634 Name: shift lever ' End Class
// Simple business object. A PartId is used to identify the type of part // but the part name can change. [<CustomEquality; NoComparison>]type Part = { PartId : int ; mutable PartName : string } with override this.GetHashCode() = hash this.PartId override this.Equals(other) = match other with | :? Part as p -> this.PartId = p.PartId | _ -> false override this.ToString() = sprintf "ID: %i Name: %s" this.PartId this.PartName[<EntryPoint>]let main argv = // We refer to System.Collections.Generic.List<'T> by its type // abbreviation ResizeArray<'T> to avoid conflicts with the F# List module. // Note: In F# code, F# linked lists are usually preferred over // ResizeArray<'T> when an extendable collection is required. let parts = ResizeArray<_>() parts.Add({PartName = "crank arm" ; PartId = 1234}) parts.Add({PartName = "chain ring"; PartId = 1334 }) parts.Add({PartName = "regular seat"; PartId = 1434 }) parts.Add({PartName = "banana seat"; PartId = 1444 }) parts.Add({PartName = "cassette"; PartId = 1534 }) parts.Add({PartName = "shift lever"; PartId = 1634 }) // Write out the parts in the ResizeArray. This will call the overridden ToString method // in the Part type printfn "" parts |> Seq.iter (fun p -> printfn "%O" p) // Check the ResizeArray for part #1734. This calls the IEquatable.Equals method // of the Part type, which checks the PartId for equality. printfn "\nContains(\"1734\"): %b" (parts.Contains({PartId=1734; PartName=""})) // Insert a new item at position 2. printfn "\nInsert(2, \"1834\")" parts.Insert(2, { PartName = "brake lever"; PartId = 1834 }) // Write out all parts parts |> Seq.iter (fun p -> printfn "%O" p) printfn "\nParts[3]: %O" parts.[3] printfn "\nRemove(\"1534\")" // This will remove part 1534 even though the PartName is different, // because the Equals method only checks PartId for equality. // Since Remove returns true or false, we need to ignore the result parts.Remove({PartId=1534; PartName="cogs"}) |> ignore // Write out all parts printfn "" parts |> Seq.iter (fun p -> printfn "%O" p) printfn "\nRemoveAt(3)" // This will remove the part at index 3. parts.RemoveAt(3) // Write out all parts printfn "" parts |> Seq.iter (fun p -> printfn "%O" p) 0 // return an integer exit code

The following example demonstrates several properties and methods of the List<T> generic class, including the Add method. The parameterless constructor is used to create a list of strings with a capacity of 0. The Capacity property is displayed, and then the Add method is used to add several items. The items are listed, and the Capacity property is displayed again, along with the Count property, to show that the capacity has been increased as needed.

(Video) C# generics ⁉️

Other properties and methods are used to search for, insert, and remove elements from the list, and finally to clear the list.

using namespace System;using namespace System::Collections::Generic;void main(){ List<String^>^ dinosaurs = gcnew List<String^>(); Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity); dinosaurs->Add("Tyrannosaurus"); dinosaurs->Add("Amargasaurus"); dinosaurs->Add("Mamenchisaurus"); dinosaurs->Add("Deinonychus"); dinosaurs->Add("Compsognathus"); Console::WriteLine(); for each(String^ dinosaur in dinosaurs ) { Console::WriteLine(dinosaur); } Console::WriteLine("\nCapacity: {0}", dinosaurs->Capacity); Console::WriteLine("Count: {0}", dinosaurs->Count); Console::WriteLine("\nContains(\"Deinonychus\"): {0}", dinosaurs->Contains("Deinonychus")); Console::WriteLine("\nInsert(2, \"Compsognathus\")"); dinosaurs->Insert(2, "Compsognathus"); Console::WriteLine(); for each(String^ dinosaur in dinosaurs ) { Console::WriteLine(dinosaur); } Console::WriteLine("\ndinosaurs[3]: {0}", dinosaurs[3]); Console::WriteLine("\nRemove(\"Compsognathus\")"); dinosaurs->Remove("Compsognathus"); Console::WriteLine(); for each(String^ dinosaur in dinosaurs ) { Console::WriteLine(dinosaur); } dinosaurs->TrimExcess(); Console::WriteLine("\nTrimExcess()"); Console::WriteLine("Capacity: {0}", dinosaurs->Capacity); Console::WriteLine("Count: {0}", dinosaurs->Count); dinosaurs->Clear(); Console::WriteLine("\nClear()"); Console::WriteLine("Capacity: {0}", dinosaurs->Capacity); Console::WriteLine("Count: {0}", dinosaurs->Count);}/* This code example produces the following output:Capacity: 0TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathusCapacity: 8Count: 5Contains("Deinonychus"): TrueInsert(2, "Compsognathus")TyrannosaurusAmargasaurusCompsognathusMamenchisaurusDeinonychusCompsognathusdinosaurs[3]: MamenchisaurusRemove("Compsognathus")TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathusTrimExcess()Capacity: 5Count: 5Clear()Capacity: 5Count: 0 */
List<string> dinosaurs = new List<string>();Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);dinosaurs.Add("Tyrannosaurus");dinosaurs.Add("Amargasaurus");dinosaurs.Add("Mamenchisaurus");dinosaurs.Add("Deinonychus");dinosaurs.Add("Compsognathus");Console.WriteLine();foreach(string dinosaur in dinosaurs){ Console.WriteLine(dinosaur);}Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);Console.WriteLine("Count: {0}", dinosaurs.Count);Console.WriteLine("\nContains(\"Deinonychus\"): {0}", dinosaurs.Contains("Deinonychus"));Console.WriteLine("\nInsert(2, \"Compsognathus\")");dinosaurs.Insert(2, "Compsognathus");Console.WriteLine();foreach(string dinosaur in dinosaurs){ Console.WriteLine(dinosaur);}// Shows accessing the list using the Item property.Console.WriteLine("\ndinosaurs[3]: {0}", dinosaurs[3]);Console.WriteLine("\nRemove(\"Compsognathus\")");dinosaurs.Remove("Compsognathus");Console.WriteLine();foreach(string dinosaur in dinosaurs){ Console.WriteLine(dinosaur);}dinosaurs.TrimExcess();Console.WriteLine("\nTrimExcess()");Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);Console.WriteLine("Count: {0}", dinosaurs.Count);dinosaurs.Clear();Console.WriteLine("\nClear()");Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);Console.WriteLine("Count: {0}", dinosaurs.Count);/* This code example produces the following output:Capacity: 0TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathusCapacity: 8Count: 5Contains("Deinonychus"): TrueInsert(2, "Compsognathus")TyrannosaurusAmargasaurusCompsognathusMamenchisaurusDeinonychusCompsognathusdinosaurs[3]: MamenchisaurusRemove("Compsognathus")TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathusTrimExcess()Capacity: 5Count: 5Clear()Capacity: 5Count: 0 */
Imports System.Collections.GenericPublic Class Example Public Shared Sub Main() Dim dinosaurs As New List(Of String) Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity) dinosaurs.Add("Tyrannosaurus") dinosaurs.Add("Amargasaurus") dinosaurs.Add("Mamenchisaurus") dinosaurs.Add("Deinonychus") dinosaurs.Add("Compsognathus") Console.WriteLine() For Each dinosaur As String In dinosaurs Console.WriteLine(dinosaur) Next Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity) Console.WriteLine("Count: {0}", dinosaurs.Count) Console.WriteLine(vbLf & "Contains(""Deinonychus""): {0}", _ dinosaurs.Contains("Deinonychus")) Console.WriteLine(vbLf & "Insert(2, ""Compsognathus"")") dinosaurs.Insert(2, "Compsognathus") Console.WriteLine() For Each dinosaur As String In dinosaurs Console.WriteLine(dinosaur) Next ' Shows how to access the list using the Item property. Console.WriteLine(vbLf & "dinosaurs(3): {0}", dinosaurs(3)) Console.WriteLine(vbLf & "Remove(""Compsognathus"")") dinosaurs.Remove("Compsognathus") Console.WriteLine() For Each dinosaur As String In dinosaurs Console.WriteLine(dinosaur) Next dinosaurs.TrimExcess() Console.WriteLine(vbLf & "TrimExcess()") Console.WriteLine("Capacity: {0}", dinosaurs.Capacity) Console.WriteLine("Count: {0}", dinosaurs.Count) dinosaurs.Clear() Console.WriteLine(vbLf & "Clear()") Console.WriteLine("Capacity: {0}", dinosaurs.Capacity) Console.WriteLine("Count: {0}", dinosaurs.Count) End SubEnd Class' This code example produces the following output:''Capacity: 0''Tyrannosaurus'Amargasaurus'Mamenchisaurus'Deinonychus'Compsognathus''Capacity: 8'Count: 5''Contains("Deinonychus"): True''Insert(2, "Compsognathus")''Tyrannosaurus'Amargasaurus'Compsognathus'Mamenchisaurus'Deinonychus'Compsognathus''dinosaurs(3): Mamenchisaurus''Remove("Compsognathus")''Tyrannosaurus'Amargasaurus'Mamenchisaurus'Deinonychus'Compsognathus''TrimExcess()'Capacity: 5'Count: 5''Clear()'Capacity: 5'Count: 0
[<EntryPoint>]let main argv = // We refer to System.Collections.Generic.List<'T> by its type // abbreviation ResizeArray<'T> to avoid conflict with the List module. // Note: In F# code, F# linked lists are usually preferred over // ResizeArray<'T> when an extendable collection is required. let dinosaurs = ResizeArray<_>() // Write out the dinosaurs in the ResizeArray. let printDinosaurs() = printfn "" dinosaurs |> Seq.iter (fun p -> printfn "%O" p) printfn "\nCapacity: %i" dinosaurs.Capacity dinosaurs.Add("Tyrannosaurus") dinosaurs.Add("Amargasaurus") dinosaurs.Add("Mamenchisaurus") dinosaurs.Add("Deinonychus") dinosaurs.Add("Compsognathus") printDinosaurs() printfn "\nCapacity: %i" dinosaurs.Capacity printfn "Count: %i" dinosaurs.Count printfn "\nContains(\"Deinonychus\"): %b" (dinosaurs.Contains("Deinonychus")) printfn "\nInsert(2, \"Compsognathus\")" dinosaurs.Insert(2, "Compsognathus") printDinosaurs() // Shows accessing the list using the Item property. printfn "\ndinosaurs[3]: %s" dinosaurs.[3] printfn "\nRemove(\"Compsognathus\")" dinosaurs.Remove("Compsognathus") |> ignore printDinosaurs() dinosaurs.TrimExcess() printfn "\nTrimExcess()" printfn "Capacity: %i" dinosaurs.Capacity printfn "Count: %i" dinosaurs.Count dinosaurs.Clear() printfn "\nClear()" printfn "Capacity: %i" dinosaurs.Capacity printfn "Count: %i" dinosaurs.Count 0 // return an integer exit code (* This code example produces the following output: Capacity: 0 TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathus Capacity: 8Count: 5 Contains("Deinonychus"): true Insert(2, "Compsognathus") TyrannosaurusAmargasaurusCompsognathusMamenchisaurusDeinonychusCompsognathus dinosaurs[3]: Mamenchisaurus Remove("Compsognathus") TyrannosaurusAmargasaurusMamenchisaurusDeinonychusCompsognathus TrimExcess()Capacity: 5Count: 5 Clear()Capacity: 5Count: 0 *)

Remarks

List<T> accepts null as a valid value for reference types and allows duplicate elements.

If Count already equals Capacity, the capacity of the List<T> is increased by automatically reallocating the internal array, and the existing elements are copied to the new array before the new element is added.

(Video) Generics In Java - Full Simple Tutorial

If Count is less than Capacity, this method is an O(1) operation. If the capacity needs to be increased to accommodate the new element, this method becomes an O(n) operation, where n is Count.

Applies to

See also

  • AddRange(IEnumerable<T>)
  • Insert(Int32, T)
  • Remove(T)
  • Count

FAQs

What is System Collections generic? ›

Contains interfaces and classes that define generic collections, which allow users to create strongly typed collections that provide better type safety and performance than non-generic strongly typed collections.

How to create a generic list in C#? ›

How to Create a Generic List Collection in C#?
  1. Add(T item): The Add(T item) method is used to add an element to the end of the Generic List. ...
  2. AddRange(IEnumerable<T> collection): The AddRange(IEnumerable<T> collection) method is used to add the Elements of the specified collection to the end of the Generic List.
May 21, 2022

How to add a list to a list in C#? ›

How to append a second list to an existing list in C#? Use the AddRange() method to append a second list to an existing list. list1. AddRange(list2);

What is generic vs non-generic collections? ›

A Generic collection is a class that provides type safety without having to derive from a base collection type and implement type-specific members. A Non-generic collection is a specialized class for data storage and retrieval that provides support for stacks, queues, lists and hash tables.

What are the benefits of generic collections? ›

There are many advantages to using generic collections and delegates:
  • Type safety. ...
  • Less code and code is more easily reused. ...
  • Better performance. ...
  • Generic delegates enable type-safe callbacks without the need to create multiple delegate classes. ...
  • Generics streamline dynamically generated code.
Aug 3, 2022

What is Genericlist in C#? ›

Generic List<T> is a generic collection in C#. The size can be dynamically increased using List, unlike Arrays. Let us see an example − We have set the List first − List<string> myList = new List<string>() Now add elements in the list − List<string> myList = new List<string>() { "mammals", "reptiles", "amphibians" }

What is a generic example? ›

generic Add to list Share. Generic refers to the members of a whole class of things — like "tissue," a generic word for any soft, thin piece of paper that's good for wiping runny noses. A generic product, whether it's a tire or donut or drug, is typical of all other products like it.

How to create list and add items in C#? ›

To add items and elements in a C# list, you need to use the Add() method. If you want to add elements of the custom classes, then you can do so by using the collection-initializer syntax.

How to add items dynamically in list in C#? ›

You need to move the declaration of the lists outside of the loop. At the moment on each loop a new list is created and the old one is lost. Change your code to look like the below, see that the lists are outside the loop so they get re-used each time rather than replaced. No problem, glad to help.

How do I add a list of elements to a list? ›

How To add Elements to a List in Python
  1. append() : append the element to the end of the list.
  2. insert() : inserts the element before the given index.
  3. extend() : extends the list by appending elements from the iterable.
  4. List Concatenation: We can use the + operator to concatenate multiple lists and create a new list.
Aug 3, 2022

How to convert generic list to ArrayList in C#? ›

string[] array1 = list. ToArray();

What is a simple example of list in C#? ›

List<T> is a class that contains multiple objects of the same data type that can be accessed using an index. For example, // list containing integer values List<int> number = new List<int>() { 1, 2, 3 }; Here, number is a List containing integer values (1, 2 and 3).

What are the different types of collections? ›

Collection types represent different ways to collect data, such as hash tables, queues, stacks, bags, dictionaries, and lists.
...
These types include:
  • Array.
  • ArrayList.
  • List<T>
  • Queue.
  • ConcurrentQueue<T>
  • Stack.
  • ConcurrentStack<T>
  • LinkedList<T>
Sep 15, 2021

What are the different collections available? ›

Some important collection classes are ArrayList, LinkedList, HashMap, TreeMap, HashSet, and TreeSet. These classes solve most of our programming needs but if we need some special collection class, we can extend them to create our custom collection class.

What is difference between collection and generics in java? ›

Generics is a programming tool to make class-independent tools, that are translated at compile time to class-specific ones. Collections is a set of tools that implement collections, like list and so on.

What is the purpose of generic? ›

Generics enable the use of stronger type-checking, the elimination of casts, and the ability to develop generic algorithms. Without generics, many of the features that we use in Java today would not be possible.

Why are generics used? ›

In a nutshell, generics enable types (classes and interfaces) to be parameters when defining classes, interfaces and methods. Much like the more familiar formal parameters used in method declarations, type parameters provide a way for you to re-use the same code with different inputs.

How are generics used in collections? ›

At a basic level, generics allow us to parameterize the type of a collection class. For example, with generics we can declare that a List x must contain only String values by writing List<String> x;. Then, the Java compiler will ensure that all values added to the list x are Strings; it will reject the command x.

Is list generic or not? ›

List<T> is a generic class that can be used with the type it is declared with; e.g., List<int> can store int s and list<string> can store string s.

How do you know if an object is generic? ›

If you want to check if it's an instance of a generic type: return list. GetType().

What is list <?> in Java? ›

List is a child interface of Collection. It is an ordered collection of objects in which duplicate values can be stored. Since List preserves the insertion order, it allows positional access and insertion of elements. List Interface is implemented by ArrayList, LinkedList, Vector and Stack classes.

What is difference between generic and collection in C#? ›

In case of collections, you can make fool to the compiler but in case of generics, you can't make fool to the compiler as shown below. Hence Generics provide Type Safety.

What are generic methods? ›

Generic methods are methods that introduce their own type parameters. This is similar to declaring a generic type, but the type parameter's scope is limited to the method where it is declared. Static and non-static generic methods are allowed, as well as generic class constructors.

What is generic code? ›

Generic programming is a style of computer programming in which algorithms are written in terms of types to-be-specified-later that are then instantiated when needed for specific types provided as parameters.

What are the generic names? ›

The generic name is the chemical name of a medicine. This name is the same no matter how many companies manufacture the medicine. When a company makes a medicine, they give it a brand name (or trade name). A generic name medicine can be made by more than one company.

What is a first generic? ›

“First generics” are just what they sound like—the first approval by FDA which permits a manufacturer to market a generic drug product in the United States. FDA considers first generics to be important to public health, and prioritizes review of these submissions.

What are generic questions? ›

Generic questions are given prepared responses

In fact, they're supposed to, and the most basic form of their preparation involves getting acquainted with what the most common interview questions are as well as how to answer them.

How to add multiple data in list in C#? ›

Add("text1");
...
Firstly you have to create a static class, let's name it ListExtensions, with a method to add elements:
  1. using System. Collections. Generic;
  2. public static class ListExtenstions.
  3. {
  4. public static void AddMany<T>(t$$anonymous$$s List<T> list, params T[] elements)
  5. {
  6. list. AddRange(elements);
  7. }
  8. }
Aug 26, 2013

How to add value to list string in C#? ›

To add string values to a list in C#, use the Add() method.

How to add items to list array in C#? ›

Adding Elements in ArrayList

Use the Add() method or object initializer syntax to add elements in an ArrayList . An ArrayList can contain multiple null and duplicate values. Use the AddRange(ICollection c) method to add an entire Array, HashTable, SortedList, ArrayList , BitArray , Queue, and Stack in the ArrayList .

How do you add items in control list by code? ›

To add items
  1. Add the string or object to the list by using the Add method of the ObjectCollection class. The collection is referenced using the Items property: C# Copy. ...
  2. Insert the string or object at the desired point in the list with the Insert method: C# Copy. ...
  3. Assign an entire array to the Items collection: C# Copy.
Sep 1, 2020

How to add item and value in ListBox in C#? ›

Step 1: Create a list box using the ListBox() constructor is provided by the ListBox class. // Creating ListBox using ListBox class constructor ListBox mylist = new ListBox(); Step 2: After creating ListBox, set the Items property of the ListBox provided by the ListBox class.

How do I add items to my ListBox? ›

To add items to a ListBox, select the ListBox control and get to the properties window, for the properties of this control. Click the ellipses (...) button next to the Items property. This opens the String Collection Editor dialog box, where you can enter the values one at a line.

How do I add a element to a list buffer? ›

To append value inside the list object we have two approach shown below: val variable_name = List(value1, value2, value3 , soon..) 2. To assign value for ListBuffer we use += operator to assign its value anytime because ListBuffer is mutable in nature.

How do you modify a list element? ›

Now we can change the item list with a different method:
  1. Change first element mylist[0]=value.
  2. Change third element mylist[2]=value.
  3. Change fourth element mylist[3]=value.
Dec 2, 2020

How to add values to list in Java? ›

There are two methods to add elements to the list.
  1. add(E e ) : appends the element at the end of the list. Since List supports Generics , the type of elements that can be added is determined when the list is created.
  2. add(int index , E element ) : inserts the element at the given index .
Aug 3, 2022

What is generic class in Java with example? ›

A Generic class simply means that the items or functions in that class can be generalized with the parameter(example T) to specify that we can add any type as a parameter in place of T like Integer, Character, String, Double or any other user-defined type.

Can you give an example of a generic method in Java? ›

For example, // creating a string type ArrayList ArrayList<String> list1 = new ArrayList<>(); // creating a integer type ArrayList ArrayList<Integer> list2 = new ArrayList<>(); In the above example, we have used the same ArrayList class to work with different types of data.

How do I create a list of object types? ›

We can create a list of objects in Python by appending class instances to the list. By this, every index in the list can point to instance attributes and methods of the class and can access them. If you observe it closely, a list of objects behaves like an array of structures in C.

Is ArrayList generic in C#? ›

C# ArrayList is a non-generic collection. The ArrayList class represents an array list and it can contain elements of any data types. The ArrayList class is defined in the System. Collections namespace.

How to convert ArrayList to string array in C#? ›

To convert an ArrayList to Array, use the ToArray() method in C#.

How to convert list values to array in C#? ›

public T[] ToArray(); This method copies the items of the List to a new array and returns the array to the caller. This method uses the Array. Copy() method internally to copy the list elements to a new array.

What are examples of lists? ›

A list is an ordered data structure with elements separated by a comma and enclosed within square brackets. For example, list1 and list2 shown below contains a single type of data. Here, list1 has integers while list2 has strings. Lists can also store mixed data types as shown in the list3 here.

What is list explain types of lists with example? ›

A list refers to any information displayed in a logical or linear form. It is a series of items written together in a meaningful group or sequence and marked by bullet points, numbers, etc. In HTML, there are three list types, each with a specific purpose and tag. In this guide, we will explore lists in HTML.

What is a list in coding example? ›

A list is a sequence of several variables, grouped together under a single name. Instead of writing a program with many variables x0 , x1 , x2 , … you can define a single variable x and access its members x[0] , x[1] , x[2] , etc.

What is a System collection? ›

Contains interfaces and classes that define various collections of objects, such as lists, queues, bit arrays, hash tables and dictionaries.

What is the difference between collections and generic collections in C#? ›

Generics are similar to collections, but implemented using Type parameters. Generic collections accept a type parameter and accept the elements of only those type for which the generic collection is instantiated. These enforce strict type checks.

What is TypeVar and generic? ›

TypeVar represents the definition and reference to a type variable. A typing. Generic represents the scoping of types, specifically to class scope.

What is collection and generic collection in C#? ›

C# includes specialized classes that store series of values or objects are called collections. There are two types of collections available in C#: non-generic collections and generic collections. The System. Collections namespace contains the non-generic collection types and System.

What are the 4 methods of data collection? ›

The main techniques for gathering data are observation, interviews, questionnaires, schedules, and surveys.

What are the 3 methods of data collection? ›

Under the main three basic groups of research methods (quantitative, qualitative and mixed), there are different tools that can be used to collect data. Interviews can be done either face-to-face or over the phone.

What are the examples of collection types? ›

Collection types represent different ways to collect data, such as hash tables, queues, stacks, bags, dictionaries, and lists.

What is generic in C# with example? ›

Generic Class

T is called type parameter, which can be used as a type of fields, properties, method parameters, return types, and delegates in the DataStore class. For example, Data is generic property because we have used a type parameter T as its type instead of the specific data type.

Which is not a type of generic collection? ›

The following are the non-generic collections: ArrayList, BitArray. ArrayList − It represents ordered collection of an object that can be indexed individually. ArrayList is an alternative to an array.

How many types of collections are there in C#? ›

Collections in C# are classified into two types - Generic collections and non-generic collections.

How do you find the type of generic type? ›

To examine a generic type and its type parameters
  1. Get an instance of Type that represents the generic type. ...
  2. Use the IsGenericType property to determine whether the type is generic, and use the IsGenericTypeDefinition property to determine whether the type is a generic type definition.
Sep 15, 2021

What are generic data types? ›

Generic Data Types
Data typeExpression supportLength
DECIMALYesYes
DOUBLEYes
FIXED
FLOATYesYes
32 more rows

What is difference between generics and collections? ›

Generics is a programming tool to make class-independent tools, that are translated at compile time to class-specific ones. Collections is a set of tools that implement collections, like list and so on.

Why do we need generics in C#? ›

Generics overview

Use generic types to maximize code reuse, type safety, and performance. The most common use of generics is to create collection classes. The . NET class library contains several generic collection classes in the System.

What is generic collection in C# interview questions? ›

Generic refers to the general form, not the specific form. In C#, generic means not tied to a particular data type. You can define generic classes, interfaces, abstract classes, fields, methods, static methods, properties, events, delegates, and operators using the type parameter and without the specific data type.

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