hashtabel与dictionary的区别-创新互联

Hashtable 支持多个线程读， 同时只有一个线程写 ， dictionary 不支持

Hashtable supports multiple reader threads with a single writer thread, while Dictionary offers no thread safety. If you need thread safety with a generic dictionary, you must implement your own synchronization or (in .NET 4.0) use ConcurrentDictionary

2 ： hash table 只能用 key 引用， 而不能 foreach , dictionary 可以。

引用 hash table:

public void MethodHashTable()
{
    Hashtable objHashTable= new Hashtable();
    objHashTable.Add(1, 100);  // int    objHashTable.Add(2.99, 200); // float    objHashTable.Add('A', 300);// char    objHashTable.Add("4", 400);// string
    lblDisplay1.Text= objHashTable[1].ToString();
    lblDisplay2.Text= objHashTable[2.99].ToString();
    lblDisplay3.Text= objHashTable['A'].ToString();
    lblDisplay4.Text= objHashTable["4"].ToString();


// ----------- Not Possible for HashTable ----------
//foreach (KeyValuePair pair in objHashTable)
//{
//    lblDisplay.Text = pair.Value + " " + lblDisplay.Text;
//}}

引用 dictionary :

public void MethodDictionary()
  {
    Dictionary dictionary = new Dictionary();
    dictionary.Add("cat", 2);
    dictionary.Add("dog", 1);
    dictionary.Add("llama", 0);
    dictionary.Add("iguana", -1);

//dictionary.Add(1, -2);// Compilation Error  foreach (KeyValuePair pair in dictionary)
    {
        lblDisplay.Text= pair.Value + " " + lblDisplay.Text;
    }
  }