CollectionExtensions.GetValueOrDefault 方法

定义

重载

GetValueOrDefault<TKey,TValue>(IReadOnlyDictionary<TKey,TValue>, TKey)

尝试获取与 dictionary 中的指定 key 相关联的值。Tries to get the value associated with the specified key in the dictionary.

GetValueOrDefault<TKey,TValue>(IReadOnlyDictionary<TKey,TValue>, TKey, TValue)

尝试获取 dictionary 中与指定键相关联的值。Tries to get the value associated with the specified key in the dictionary.

GetValueOrDefault<TKey,TValue>(IReadOnlyDictionary<TKey,TValue>, TKey)

尝试获取与 dictionary 中的指定 key 相关联的值。Tries to get the value associated with the specified key in the dictionary.

public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
 static TValue GetValueOrDefault(System::Collections::Generic::IReadOnlyDictionary<TKey, TValue> ^ dictionary, TKey key);
public static TValue GetValueOrDefault<TKey,TValue> (this System.Collections.Generic.IReadOnlyDictionary<TKey,TValue> dictionary, TKey key);
static member GetValueOrDefault : System.Collections.Generic.IReadOnlyDictionary<'Key, 'Value> * 'Key -> 'Value
<Extension()>
Public Function GetValueOrDefault(Of TKey, TValue) (dictionary As IReadOnlyDictionary(Of TKey, TValue), key As TKey) As TValue

类型参数

TKey

字典中的键的类型。The type of the keys in the dictionary.

TValue

字典中的值的类型。The type of the values in the dictionary.

参数

dictionary
IReadOnlyDictionary<TKey,TValue>

一个字典,其键类型为 TKey,其值类型为 TValueA dictionary with keys of type TKey and values of type TValue.

key
TKey

要获取的值的键。The key of the value to get.

返回

TValue

一个 TValue 实例。A TValue instance. 如果方法成功,则返回的对象是与指定的 key 相关联的值。When the method is successful, the returned object is the value associated with the specified key. 如果方法失败,则返回 TValuedefault 值。When the method fails, it returns the default value for TValue.

异常

dictionarynulldictionary is null.

GetValueOrDefault<TKey,TValue>(IReadOnlyDictionary<TKey,TValue>, TKey, TValue)

尝试获取 dictionary 中与指定键相关联的值。Tries to get the value associated with the specified key in the dictionary.

public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
 static TValue GetValueOrDefault(System::Collections::Generic::IReadOnlyDictionary<TKey, TValue> ^ dictionary, TKey key, TValue defaultValue);
public static TValue GetValueOrDefault<TKey,TValue> (this System.Collections.Generic.IReadOnlyDictionary<TKey,TValue> dictionary, TKey key, TValue defaultValue);
static member GetValueOrDefault : System.Collections.Generic.IReadOnlyDictionary<'Key, 'Value> * 'Key * 'Value -> 'Value
<Extension()>
Public Function GetValueOrDefault(Of TKey, TValue) (dictionary As IReadOnlyDictionary(Of TKey, TValue), key As TKey, defaultValue As TValue) As TValue

类型参数

TKey

字典中的键的类型。The type of the keys in the dictionary.

TValue

字典中的值的类型。The type of the values in the dictionary.

参数

dictionary
IReadOnlyDictionary<TKey,TValue>

一个字典,其键类型为 TKey,其值类型为 TValueA dictionary with keys of type TKey and values of type TValue.

key
TKey

要获取的值的键。The key of the value to get.

defaultValue
TValue

dictionary 找不到与指定的 key 关联的值时要返回的默认值。The default value to return when the dictionary cannot find a value associated with the specified key.

返回

TValue

一个 TValue 实例。A TValue instance. 如果方法成功,则返回的对象是与指定的 key 相关联的值。When the method is successful, the returned object is the value associated with the specified key. 如果方法失败,则返回 defaultValueWhen the method fails, it returns defaultValue.

异常

dictionarynulldictionary is null.

适用于