Some similarities and differences of dictionary and Hashtable

Dictionaryand Hashtable differences:

and difference Hashtable Dictionary

Dictionary	Hashtable
Support Paradigm	Not supported
Need to do thread synchronization yourself	Thread-safe types can be obtained by calling the Synchronized () method
Enum type is KeyValuePair	Enumeration type isDictionaryEntry
. Net 2.0 starts with	. Net 1.0 starts with
Under the System.Collections.Generic namespace	Under the system.collections namespace
Throws an exception when getting the same nonexistent key	Returns NULL when getting the same nonexistent key
Value types do not need to be boxed/unboxing and may be faster	Value type values types need to be boxed/unboxing boxing/unboxing

Same point :

Internal is hashtable implementation, through key access to data faster

Need to be immutable, the only key

Key all need to have their ownGetHashCode()方法

 

other similar. Net collections (for alternative Dictionary和Hashtable的 alternatives)

ConcurrentDictionary-For multi-concurrency, thread-safe dictionaries

Under the Hybriddictionary-system.collections.specialized namespace, performance is optimized (when the collection is small, use listdictionary to implement IDictionary, and then when the collection becomes larger, Switch to Hashtable. ）

Under the Ordereddictionary-system.collections.specialized namespace, the value can be accessed by a numeric index because the element is already specified when it is added. public void Insert (int index, object key, object value);

SortedDictionary-Automatically sorted when an element is inserted

Under the Stringdictionary-system.collections.specialized namespace, the keys and values are strongly typed as strings rather than objects, and the corresponding optimizations are made.

Some similarities and differences of dictionary and Hashtable