ReadOnlyCollection<T>.Contains(T) Metode
Definisi
Penting
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Menentukan apakah elemen berada di ReadOnlyCollection<T>.
public:
virtual bool Contains(T value);
public bool Contains (T value);
abstract member Contains : 'T -> bool
override this.Contains : 'T -> bool
Public Function Contains (value As T) As Boolean
Parameter
- value
- T
Objek yang akan ditemukan di ReadOnlyCollection<T>. Nilainya bisa null
untuk jenis referensi.
Mengembalikan
true
jika value
ditemukan di ReadOnlyCollection<T>; jika tidak, false
.
Penerapan
Contoh
Contoh kode berikut menunjukkan beberapa anggota ReadOnlyCollection<T> kelas. Contoh kode membuat List<T> string dan menambahkan empat nama dinosang ke dalamnya. Contoh kode kemudian membungkus daftar dalam ReadOnlyCollection<T>.
Setelah menunjukkan Count, , Item[]Contains, dan IList.IndexOf anggota, contoh kode menunjukkan bahwa ReadOnlyCollection<T> hanya pembungkus ReadOnlyCollection<T>untuk yang asli List<T> dengan menambahkan item baru ke List<T> dan menampilkan konten .
Akhirnya, contoh kode membuat array yang lebih besar dari koleksi dan menggunakan CopyTo metode untuk menyisipkan elemen koleksi ke tengah array.
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;
void main()
{
List<String^>^ dinosaurs = gcnew List<String^>();
dinosaurs->Add("Tyrannosaurus");
dinosaurs->Add("Amargasaurus");
dinosaurs->Add("Deinonychus");
dinosaurs->Add("Compsognathus");
ReadOnlyCollection<String^>^ readOnlyDinosaurs =
gcnew ReadOnlyCollection<String^>(dinosaurs);
Console::WriteLine();
for each(String^ dinosaur in readOnlyDinosaurs )
{
Console::WriteLine(dinosaur);
}
Console::WriteLine("\nCount: {0}", readOnlyDinosaurs->Count);
Console::WriteLine("\nContains(\"Deinonychus\"): {0}",
readOnlyDinosaurs->Contains("Deinonychus"));
Console::WriteLine("\nreadOnlyDinosaurs[3]: {0}",
readOnlyDinosaurs[3]);
Console::WriteLine("\nIndexOf(\"Compsognathus\"): {0}",
readOnlyDinosaurs->IndexOf("Compsognathus"));
Console::WriteLine("\nInsert into the wrapped List:");
Console::WriteLine("Insert(2, \"Oviraptor\")");
dinosaurs->Insert(2, "Oviraptor");
Console::WriteLine();
for each( String^ dinosaur in readOnlyDinosaurs )
{
Console::WriteLine(dinosaur);
}
array<String^>^ dinoArray =
gcnew array<String^>(readOnlyDinosaurs->Count + 2);
readOnlyDinosaurs->CopyTo(dinoArray, 1);
Console::WriteLine("\nCopied array has {0} elements:",
dinoArray->Length);
for each( String^ dinosaur in dinoArray )
{
Console::WriteLine("\"{0}\"", dinosaur);
}
}
/* This code example produces the following output:
Tyrannosaurus
Amargasaurus
Deinonychus
Compsognathus
Count: 4
Contains("Deinonychus"): True
readOnlyDinosaurs[3]: Compsognathus
IndexOf("Compsognathus"): 3
Insert into the wrapped List:
Insert(2, "Oviraptor")
Tyrannosaurus
Amargasaurus
Oviraptor
Deinonychus
Compsognathus
Copied array has 7 elements:
""
"Tyrannosaurus"
"Amargasaurus"
"Oviraptor"
"Deinonychus"
"Compsognathus"
""
*/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
public class Example
{
public static void Main()
{
List<string> dinosaurs = new List<string>();
dinosaurs.Add("Tyrannosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Deinonychus");
dinosaurs.Add("Compsognathus");
ReadOnlyCollection<string> readOnlyDinosaurs =
new ReadOnlyCollection<string>(dinosaurs);
Console.WriteLine();
foreach( string dinosaur in readOnlyDinosaurs )
{
Console.WriteLine(dinosaur);
}
Console.WriteLine("\nCount: {0}", readOnlyDinosaurs.Count);
Console.WriteLine("\nContains(\"Deinonychus\"): {0}",
readOnlyDinosaurs.Contains("Deinonychus"));
Console.WriteLine("\nreadOnlyDinosaurs[3]: {0}",
readOnlyDinosaurs[3]);
Console.WriteLine("\nIndexOf(\"Compsognathus\"): {0}",
readOnlyDinosaurs.IndexOf("Compsognathus"));
Console.WriteLine("\nInsert into the wrapped List:");
Console.WriteLine("Insert(2, \"Oviraptor\")");
dinosaurs.Insert(2, "Oviraptor");
Console.WriteLine();
foreach( string dinosaur in readOnlyDinosaurs )
{
Console.WriteLine(dinosaur);
}
string[] dinoArray = new string[readOnlyDinosaurs.Count + 2];
readOnlyDinosaurs.CopyTo(dinoArray, 1);
Console.WriteLine("\nCopied array has {0} elements:",
dinoArray.Length);
foreach( string dinosaur in dinoArray )
{
Console.WriteLine("\"{0}\"", dinosaur);
}
}
}
/* This code example produces the following output:
Tyrannosaurus
Amargasaurus
Deinonychus
Compsognathus
Count: 4
Contains("Deinonychus"): True
readOnlyDinosaurs[3]: Compsognathus
IndexOf("Compsognathus"): 3
Insert into the wrapped List:
Insert(2, "Oviraptor")
Tyrannosaurus
Amargasaurus
Oviraptor
Deinonychus
Compsognathus
Copied array has 7 elements:
""
"Tyrannosaurus"
"Amargasaurus"
"Oviraptor"
"Deinonychus"
"Compsognathus"
""
*/
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
Public Class Example
Public Shared Sub Main()
Dim dinosaurs As New List(Of String)
dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Deinonychus")
dinosaurs.Add("Compsognathus")
Dim readOnlyDinosaurs As _
New ReadOnlyCollection(Of String)(dinosaurs)
Console.WriteLine()
For Each dinosaur As String In readOnlyDinosaurs
Console.WriteLine(dinosaur)
Next
Console.WriteLine(vbLf & "Count: {0}", _
readOnlyDinosaurs.Count)
Console.WriteLine(vbLf & "Contains(""Deinonychus""): {0}", _
readOnlyDinosaurs.Contains("Deinonychus"))
Console.WriteLine(vbLf & _
"readOnlyDinosaurs(3): {0}", readOnlyDinosaurs(3))
Console.WriteLine(vbLf & "IndexOf(""Compsognathus""): {0}", _
readOnlyDinosaurs.IndexOf("Compsognathus"))
Console.WriteLine(vbLf & "Insert into the wrapped List:")
Console.WriteLine("Insert(2, ""Oviraptor"")")
dinosaurs.Insert(2, "Oviraptor")
Console.WriteLine()
For Each dinosaur As String In readOnlyDinosaurs
Console.WriteLine(dinosaur)
Next
Dim dinoArray(readOnlyDinosaurs.Count + 1) As String
readOnlyDinosaurs.CopyTo(dinoArray, 1)
Console.WriteLine(vbLf & "Copied array has {0} elements:", _
dinoArray.Length)
For Each dinosaur As String In dinoArray
Console.WriteLine("""{0}""", dinosaur)
Next
End Sub
End Class
' This code example produces the following output:
'
'Tyrannosaurus
'Amargasaurus
'Deinonychus
'Compsognathus
'
'Count: 4
'
'Contains("Deinonychus"): True
'
'readOnlyDinosaurs(3): Compsognathus
'
'IndexOf("Compsognathus"): 3
'
'Insert into the wrapped List:
'Insert(2, "Oviraptor")
'
'Tyrannosaurus
'Amargasaurus
'Oviraptor
'Deinonychus
'Compsognathus
'
'Copied array has 7 elements:
'""
'"Tyrannosaurus"
'"Amargasaurus"
'"Oviraptor"
'"Deinonychus"
'"Compsognathus"
'""
Keterangan
Metode ini menentukan kesetaraan menggunakan perbandingan EqualityComparer<T>.Defaultkesetaraan default .
Metode ini melakukan pencarian linier; oleh karena itu, metode ini adalah operasi O(n
), di mana n
adalah Count.