About listBox1.DataSource

昨天发现的， listBox1.DataSource重新绑定的时候，一定要listBox1.DataSource = null; ，然后才能实现listBox1的刷新！！！怎么也不理解为什么！
结果是

In an ArrayList, the 'plumbing' is not available to support two-way binding as with a dataset. So, you have to handle the synchronization yourself. One way to do this is to set the listBox1.DataSource to null and then reset it to your ArrayList. Another way is to use the CurrencyManager as shown in the code below.

     private System.Windows.Forms.ListBox listBox1; 
 
     private System.Windows.Forms.Button button1; 
 
     private ArrayList myArrayList; 
 

 
     public Form1() 
 
     { 
 
          // 
 
          // Required for Windows Form Designer support 
 
          // 
 
          InitializeComponent(); 
 

 
          myArrayList = new ArrayList(); 
 

 
          myArrayList.Add("orange"); 
 
          myArrayList.Add("green"); 
 
          myArrayList.Add("blue"); 
 
          myArrayList.Add("red"); 
 
           
 
          listBox1.DataSource = myArrayList; 
 
     } 
 
      
 
     //change the arraylist 
 
     private void button1_Click(object sender, System.EventArgs e) 
 
     { 
 
          myArrayList[1] = "pink"; 
 
          myArrayList.Add("lavendar"); 
 

 
          //use currency manger to sync up the listbox 
 
          BindingManagerBase bm = this.listBox1.BindingContext[myArrayList]; 
 
          CurrencyManager cm = (CurrencyManager) bm; 
 
          if (cm != null) 
 
               cm.Refresh(); 
 
                
 
          //Or, you can just reset the datasource 
 
          //listBox1.DataSource = null; 
 
          //listBox1.DataSource = myArrayList; 
 
     }