IDictionary.Add(Object, Object) 方法

定义

IDictionary 对象中添加一个带有所提供的键和值的元素。Adds an element with the provided key and value to the IDictionary object.

public:
 void Add(System::Object ^ key, System::Object ^ value);
public void Add (object key, object value);
abstract member Add : obj * obj -> unit
Public Sub Add (key As Object, value As Object)

参数

key
Object

用作要添加的元素的键的 ObjectThe Object to use as the key of the element to add.

value
Object

用作要添加的元素的键的 ObjectThe Object to use as the value of the element to add.

异常

keynullkey is null.

IDictionary 对象中已存在具有相同键的元素。An element with the same key already exists in the IDictionary object.

IDictionary 为只读。The IDictionary is read-only.

-or- IDictionary 具有固定的大小。The IDictionary has a fixed size.

示例

下面的代码示例演示如何实现Add方法。The following code example demonstrates how to implement the Add method. 此代码示例是为IDictionary类提供的更大示例的一部分。This code example is part of a larger example provided for the IDictionary class.

public:
    virtual void Add(Object^ key, Object^ value)
    {
        // Add the new key/value pair even if this key already exists
        // in the dictionary.
        if (itemsInUse == items->Length)
        {
            throw gcnew InvalidOperationException
                ("The dictionary cannot hold any more items.");
        }
        items[itemsInUse++] = gcnew DictionaryEntry(key, value);
    }
public void Add(object key, object value) 
{
    // Add the new key/value pair even if this key already exists in the dictionary.
    if (ItemsInUse == items.Length)
        throw new InvalidOperationException("The dictionary cannot hold any more items.");
    items[ItemsInUse++] = new DictionaryEntry(key, value);
}
Public Sub Add(ByVal key As Object, ByVal value As Object) Implements IDictionary.Add

    ' Add the new key/value pair even if this key already exists in the dictionary.
    If ItemsInUse = items.Length Then
        Throw New InvalidOperationException("The dictionary cannot hold any more items.")
    End If
    items(ItemsInUse) = New DictionaryEntry(key, value)
    ItemsInUse = ItemsInUse + 1
End Sub

注解

你还可以使用Item[Object]属性来添加新元素, 方法是设置字典中不存在的键的值 ( myCollection["myNonexistentKey"] = myValue例如)。You can also use the Item[Object] property to add new elements by setting the value of a key that does not exist in the dictionary (for example, myCollection["myNonexistentKey"] = myValue). 但是, 如果字典中已存在指定的键, 则设置Item[Object]属性会覆盖旧值。However, if the specified key already exists in the dictionary, setting the Item[Object] property overwrites the old value. 与此Add相反, 方法不会修改现有元素。In contrast, the Add method does not modify existing elements.

实现在是否允许键null时可能有所不同。Implementations can vary in whether they allow the key to be null.

适用于

另请参阅