LinkedList<T> Classe

Definição

generic <typename T>
public ref class LinkedList : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::ICollection

generic <typename T>
public ref class LinkedList : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::ICollection, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class LinkedList : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::ICollection, System::Runtime::Serialization::IDeserializationCallback, System::Runtime::Serialization::ISerializable

generic <typename T>
public ref class LinkedList : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::ICollection

public class LinkedList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.ICollection

[System.Runtime.InteropServices.ComVisible(false)]
[System.Serializable]
public class LinkedList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.ICollection, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

[System.Runtime.InteropServices.ComVisible(false)]
[System.Serializable]
public class LinkedList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.ICollection, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

public class LinkedList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.ICollection

public class LinkedList<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.ICollection, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable

type LinkedList<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface IReadOnlyCollection<'T>
    interface ICollection

[<System.Runtime.InteropServices.ComVisible(false)>]
[<System.Serializable>]
type LinkedList<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface ICollection
    interface IEnumerable
    interface ISerializable
    interface IDeserializationCallback

[<System.Runtime.InteropServices.ComVisible(false)>]
[<System.Serializable>]
type LinkedList<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface ICollection
    interface IReadOnlyCollection<'T>
    interface ISerializable
    interface IDeserializationCallback

type LinkedList<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface ICollection
    interface IEnumerable

type LinkedList<'T> = class
    interface ICollection<'T>
    interface seq<'T>
    interface IEnumerable
    interface IReadOnlyCollection<'T>
    interface ICollection
    interface IDeserializationCallback
    interface ISerializable

Public Class LinkedList(Of T)
Implements ICollection, ICollection(Of T), IEnumerable(Of T), IReadOnlyCollection(Of T)

Public Class LinkedList(Of T)
Implements ICollection, ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), ISerializable

Public Class LinkedList(Of T)
Implements ICollection, ICollection(Of T), IDeserializationCallback, IEnumerable(Of T), IReadOnlyCollection(Of T), ISerializable

Public Class LinkedList(Of T)
Implements ICollection, ICollection(Of T), IEnumerable(Of T)

Parâmetros de Tipo Genérico

Herança

Object

LinkedList<T>

Atributos

ComVisibleAttribute SerializableAttribute

Implementações

ICollection<T> IEnumerable<T> IReadOnlyCollection<T> ICollection IEnumerable IDeserializationCallback ISerializable

Exemplos

O exemplo de código seguinte demonstra muitas características da LinkedList<T> classe.

using System;
using System.Text;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create the link list.
        string[] words =
            { "the", "fox", "jumps", "over", "the", "dog" };
        LinkedList<string> sentence = new LinkedList<string>(words);
        Display(sentence, "The linked list values:");

        // Add the word 'today' to the beginning of the linked list.
        sentence.AddFirst("today");
        Display(sentence, "Test 1: Add 'today' to beginning of the list:");

        // Move the first node to be the last node.
        LinkedListNode<string> mark1 = sentence.First;
        sentence.RemoveFirst();
        sentence.AddLast(mark1);
        Display(sentence, "Test 2: Move first node to be last node:");

        // Change the last node to 'yesterday'.
        sentence.RemoveLast();
        sentence.AddLast("yesterday");
        Display(sentence, "Test 3: Change the last node to 'yesterday':");

        // Move the last node to be the first node.
        mark1 = sentence.Last;
        sentence.RemoveLast();
        sentence.AddFirst(mark1);
        Display(sentence, "Test 4: Move last node to be first node:");

        // Indicate the last occurence of 'the'.
        sentence.RemoveFirst();
        LinkedListNode<string> current = sentence.FindLast("the");
        IndicateNode(current, "Test 5: Indicate last occurence of 'the':");

        // Add 'lazy' and 'old' after 'the' (the LinkedListNode named current).
        sentence.AddAfter(current, "old");
        sentence.AddAfter(current, "lazy");
        IndicateNode(current, "Test 6: Add 'lazy' and 'old' after 'the':");

        // Indicate 'fox' node.
        current = sentence.Find("fox");
        IndicateNode(current, "Test 7: Indicate the 'fox' node:");

        // Add 'quick' and 'brown' before 'fox':
        sentence.AddBefore(current, "quick");
        sentence.AddBefore(current, "brown");
        IndicateNode(current, "Test 8: Add 'quick' and 'brown' before 'fox':");

        // Keep a reference to the current node, 'fox',
        // and to the previous node in the list. Indicate the 'dog' node.
        mark1 = current;
        LinkedListNode<string> mark2 = current.Previous;
        current = sentence.Find("dog");
        IndicateNode(current, "Test 9: Indicate the 'dog' node:");

        // The AddBefore method throws an InvalidOperationException
        // if you try to add a node that already belongs to a list.
        Console.WriteLine("Test 10: Throw exception by adding node (fox) already in the list:");
        try
        {
            sentence.AddBefore(current, mark1);
        }
        catch (InvalidOperationException ex)
        {
            Console.WriteLine("Exception message: {0}", ex.Message);
        }
        Console.WriteLine();

        // Remove the node referred to by mark1, and then add it
        // before the node referred to by current.
        // Indicate the node referred to by current.
        sentence.Remove(mark1);
        sentence.AddBefore(current, mark1);
        IndicateNode(current, "Test 11: Move a referenced node (fox) before the current node (dog):");

        // Remove the node referred to by current.
        sentence.Remove(current);
        IndicateNode(current, "Test 12: Remove current node (dog) and attempt to indicate it:");

        // Add the node after the node referred to by mark2.
        sentence.AddAfter(mark2, current);
        IndicateNode(current, "Test 13: Add node removed in test 12 after a referenced node (brown):");

        // The Remove method finds and removes the
        // first node that that has the specified value.
        sentence.Remove("old");
        Display(sentence, "Test 14: Remove node that has the value 'old':");

        // When the linked list is cast to ICollection(Of String),
        // the Add method adds a node to the end of the list.
        sentence.RemoveLast();
        ICollection<string> icoll = sentence;
        icoll.Add("rhinoceros");
        Display(sentence, "Test 15: Remove last node, cast to ICollection, and add 'rhinoceros':");

        Console.WriteLine("Test 16: Copy the list to an array:");
        // Create an array with the same number of
        // elements as the linked list.
        string[] sArray = new string[sentence.Count];
        sentence.CopyTo(sArray, 0);

        foreach (string s in sArray)
        {
            Console.WriteLine(s);
        }

        Console.WriteLine("Test 17: linked list Contains 'jumps' = {0}",
            sentence.Contains("jumps"));
        
        // Release all the nodes.
        sentence.Clear();

        Console.WriteLine();
        Console.WriteLine("Test 18: Cleared linked list Contains 'jumps' = {0}",
            sentence.Contains("jumps"));

        Console.ReadLine();
    }

    private static void Display(LinkedList<string> words, string test)
    {
        Console.WriteLine(test);
        foreach (string word in words)
        {
            Console.Write(word + " ");
        }
        Console.WriteLine();
        Console.WriteLine();
    }

    private static void IndicateNode(LinkedListNode<string> node, string test)
    {
        Console.WriteLine(test);
        if (node.List == null)
        {
            Console.WriteLine("Node '{0}' is not in the list.\n",
                node.Value);
            return;
        }

        StringBuilder result = new StringBuilder("(" + node.Value + ")");
        LinkedListNode<string> nodeP = node.Previous;

        while (nodeP != null)
        {
            result.Insert(0, nodeP.Value + " ");
            nodeP = nodeP.Previous;
        }

        node = node.Next;
        while (node != null)
        {
            result.Append(" " + node.Value);
            node = node.Next;
        }

        Console.WriteLine(result);
        Console.WriteLine();
    }
}

//This code example produces the following output:
//
//The linked list values:
//the fox jumps over the dog

//Test 1: Add 'today' to beginning of the list:
//today the fox jumps over the dog

//Test 2: Move first node to be last node:
//the fox jumps over the dog today

//Test 3: Change the last node to 'yesterday':
//the fox jumps over the dog yesterday

//Test 4: Move last node to be first node:
//yesterday the fox jumps over the dog

//Test 5: Indicate last occurence of 'the':
//the fox jumps over (the) dog

//Test 6: Add 'lazy' and 'old' after 'the':
//the fox jumps over (the) lazy old dog

//Test 7: Indicate the 'fox' node:
//the (fox) jumps over the lazy old dog

//Test 8: Add 'quick' and 'brown' before 'fox':
//the quick brown (fox) jumps over the lazy old dog

//Test 9: Indicate the 'dog' node:
//the quick brown fox jumps over the lazy old (dog)

//Test 10: Throw exception by adding node (fox) already in the list:
//Exception message: The LinkedList node belongs a LinkedList.

//Test 11: Move a referenced node (fox) before the current node (dog):
//the quick brown jumps over the lazy old fox (dog)

//Test 12: Remove current node (dog) and attempt to indicate it:
//Node 'dog' is not in the list.

//Test 13: Add node removed in test 12 after a referenced node (brown):
//the quick brown (dog) jumps over the lazy old fox

//Test 14: Remove node that has the value 'old':
//the quick brown dog jumps over the lazy fox

//Test 15: Remove last node, cast to ICollection, and add 'rhinoceros':
//the quick brown dog jumps over the lazy rhinoceros

//Test 16: Copy the list to an array:
//the
//quick
//brown
//dog
//jumps
//over
//the
//lazy
//rhinoceros

//Test 17: linked list Contains 'jumps'= True

//Test 18: Cleared linked list Contains 'jumps'  = False
//

Imports System.Text
Imports System.Collections.Generic
Public Class Example

    Public Shared Sub Main()
        ' Create the link list.
        Dim words() As String = {"the", "fox", _
            "jumps", "over", "the", "dog"}
        Dim sentence As New LinkedList(Of String)(words)
        Console.WriteLine("sentence.Contains(""jumps"") = {0}", _
            sentence.Contains("jumps"))
        Display(sentence, "The linked list values:")
        ' Add the word 'today' to the beginning of the linked list.
        sentence.AddFirst("today")
        Display(sentence, "Test 1: Add 'today' to beginning of the list:")
        ' Move the first node to be the last node.
        Dim mark1 As LinkedListNode(Of String) = sentence.First
        sentence.RemoveFirst()
        sentence.AddLast(mark1)
        Display(sentence, "Test 2: Move first node to be last node:")
        ' Change the last node to 'yesterday'.
        sentence.RemoveLast()
        sentence.AddLast("yesterday")
        Display(sentence, "Test 3: Change the last node to 'yesterday':")
        ' Move the last node to be the first node.
        mark1 = sentence.Last
        sentence.RemoveLast()
        sentence.AddFirst(mark1)
        Display(sentence, "Test 4: Move last node to be first node:")
        ' Indicate the last occurence of 'the'.
        sentence.RemoveFirst()
        Dim current As LinkedListNode(Of String) = sentence.FindLast("the")
        IndicateNode(current, "Test 5: Indicate last occurence of 'the':")
        ' Add 'lazy' and 'old' after 'the' (the LinkedListNode named current).
        sentence.AddAfter(current, "old")
        sentence.AddAfter(current, "lazy")
        IndicateNode(current, "Test 6: Add 'lazy' and 'old' after 'the':")
        ' Indicate 'fox' node.
        current = sentence.Find("fox")
        IndicateNode(current, "Test 7: Indicate the 'fox' node:")
        ' Add 'quick' and 'brown' before 'fox':
        sentence.AddBefore(current, "quick")
        sentence.AddBefore(current, "brown")
        IndicateNode(current, "Test 8: Add 'quick' and 'brown' before 'fox':")
        ' Keep a reference to the current node, 'fox',
        ' and to the previous node in the list. Indicate the 'dog' node.
        mark1 = current
        Dim mark2 As LinkedListNode(Of String) = current.Previous
        current = sentence.Find("dog")
        IndicateNode(current, "Test 9: Indicate the 'dog' node:")
        ' The AddBefore method throws an InvalidOperationException
        ' if you try to add a node that already belongs to a list.
        Console.WriteLine("Test 10: Throw exception by adding node (fox) already in the list:")
        Try
            sentence.AddBefore(current, mark1)
        Catch ex As InvalidOperationException
            Console.WriteLine("Exception message: {0}", ex.Message)
        End Try
        Console.WriteLine()
        ' Remove the node referred to by mark1, and then add it
        ' before the node referred to by current.
        ' Indicate the node referred to by current.
        sentence.Remove(mark1)
        sentence.AddBefore(current, mark1)
        IndicateNode(current, "Test 11: Move a referenced node (fox) before the current node (dog):")
        ' Remove the node referred to by current. 
        sentence.Remove(current)
        IndicateNode(current, "Test 12: Remove current node (dog) and attempt to indicate it:")
        ' Add the node after the node referred to by mark2.
        sentence.AddAfter(mark2, current)
        IndicateNode(current, "Test 13: Add node removed in test 11 after a referenced node (brown):")
        ' The Remove method finds and removes the
        ' first node that that has the specified value.
        sentence.Remove("old")
        Display(sentence, "Test 14: Remove node that has the value 'old':")
        ' When the linked list is cast to ICollection(Of String),
        ' the Add method adds a node to the end of the list.
        sentence.RemoveLast()
        Dim icoll As ICollection(Of String) = sentence
        icoll.Add("rhinoceros")
        Display(sentence, "Test 15: Remove last node, cast to ICollection, and add 'rhinoceros':")
        Console.WriteLine("Test 16: Copy the list to an array:")
        ' Create an array with the same number of
        ' elements as the inked list.
        Dim sArray() As String = New String((sentence.Count) - 1) {}
        sentence.CopyTo(sArray, 0)
        For Each s As String In sArray
            Console.WriteLine(s)
        Next

        ' Release all the nodes.
        sentence.Clear()
        Console.WriteLine()
        Console.WriteLine("Test 17: Clear linked list. Contains 'jumps' = {0}", sentence.Contains("jumps"))
        Console.ReadLine()
    End Sub

    Private Shared Sub Display(ByVal words As LinkedList(Of String), ByVal test As String)
        Console.WriteLine(test)
        For Each word As String In words
            Console.Write((word + " "))
        Next
        Console.WriteLine()
        Console.WriteLine()
    End Sub

    Private Shared Sub IndicateNode(ByVal node As LinkedListNode(Of String), ByVal test As String)
        Console.WriteLine(test)
        If IsNothing(node.List) Then
            Console.WriteLine("Node '{0}' is not in the list." & vbLf, node.Value)
            Return
        End If
        Dim result As StringBuilder = New StringBuilder(("(" _
                        + (node.Value + ")")))
        Dim nodeP As LinkedListNode(Of String) = node.Previous

        While (Not (nodeP) Is Nothing)
            result.Insert(0, (nodeP.Value + " "))
            nodeP = nodeP.Previous

        End While
        node = node.Next

        While (Not (node) Is Nothing)
            result.Append((" " + node.Value))
            node = node.Next

        End While
        Console.WriteLine(result)
        Console.WriteLine()
    End Sub
End Class
'This code example produces the following output:
'
'The linked list values:
'the fox jumps over the dog 
'Test 1: Add 'today' to beginning of the list:
'today the fox jumps over the dog

'Test 2: Move first node to be last node:
'the fox jumps over the dog today

'Test 3: Change the last node to 'yesterday':
'the fox jumps over the dog yesterday

'Test 4: Move last node to be first node:
'yesterday the fox jumps over the dog

'Test 5: Indicate last occurence of 'the':
'the fox jumps over (the) dog

'Test 6: Add 'lazy' and 'old' after 'the':
'the fox jumps over (the) lazy old dog

'Test 7: Indicate the 'fox' node:
'the (fox) jumps over the lazy old dog

'Test 8: Add 'quick' and 'brown' before 'fox':
'the quick brown (fox) jumps over the lazy old dog

'Test 9: Indicate the 'dog' node:
'the quick brown fox jumps over the lazy old (dog)

'Test 10: Throw exception by adding node (fox) already in the list:
'Exception message: The LinkedList node belongs a LinkedList.

'Test 11: Move a referenced node (fox) before the current node (dog):
'the quick brown jumps over the lazy old fox (dog)

'Test 12: Remove current node (dog) and attempt to indicate it:
'Node 'dog' is not in the list.

'Test 13: Add node removed in test 11 after a referenced node (brown):
'the quick brown (dog) jumps over the lazy old fox

'Test 14: Remove node that has the value 'old':
'the quick brown dog jumps over the lazy fox 

'Test 15: Remove last node, cast to ICollection, and add 'rhinoceros':
'the quick brown dog jumps over the lazy rhinoceros

'Test 16: Copy the list to an array:
'the
'quick
'brown
'dog
'jumps
'over
'the
'lazy
'rhinoceros

'Test 17: Clear linked list. Contains 'jumps' = False
'

Observações

LinkedList<T> é uma lista ligada de uso geral. Suporta enumeradores e implementa a interface ICollection, consistente com outras classes de coleção no .NET Framework.

LinkedList<T> fornece nós separados do tipo LinkedListNode<T>, pelo que a inserção e remoção são operações O(1).

Pode remover nós e voltar a inseri-los, seja na mesma lista ou noutra lista, o que resulta em não haver objetos adicionais alocados ao heap. Como a lista também mantém uma contagem interna, obter a Count propriedade é uma operação O(1).

Cada nó num LinkedList<T> objeto é do tipo LinkedListNode<T>. Como o LinkedList<T> está duplamente ligado, cada nó aponta para a frente para o Next nó e para trás para o nó.Previous

Listas que contêm tipos de referência têm melhor desempenho quando um nó e o seu valor são criados ao mesmo tempo. LinkedList<T> aceita null como propriedade válida Value para tipos de referência e permite valores duplicados.

Se o LinkedList<T> for vazio, as First propriedades e Last contêm null.

A LinkedList<T> classe não suporta encadeamento, divisão, ciclos ou outras funcionalidades que possam deixar a lista num estado inconsistente. A lista mantém-se consistente num único tópico. O único cenário multithread suportado por LinkedList<T> são as operações de leitura multithread.

Segurança de Thread

Este tipo não está seguro para threads. Se for LinkedList<T> necessário aceder por múltiplos threads, terá de implementar o seu próprio mecanismo de sincronização.

A LinkedList<T> pode suportar múltiplos leitores em simultâneo, desde que a coleção não seja modificada. Ainda assim, enumerar através de uma coleção não é, intrinsecamente, um procedimento seguro para threads. No raro caso em que uma enumeração envolva acessos de escrita, a coleção deve ser bloqueada durante toda a enumeração. Para permitir que a coleção seja acedida por múltiplos threads para leitura e escrita, deve implementar a sua própria sincronização.

Ver também

• LinkedListNode<T>