Silverlight中为ComboBox设定当前选择项,真麻烦

今天用到了ComboBox控件，像往常一样根据以往使用WebForm的DropDownlist或者WinForm中ComboBox控件的经验来使用Silverlight的ComboBox控件，

可是遇到麻烦了。

为ComboBox绑定了某个列表，然后需要根据我当前的值去指定ComboBox的当前选择项。比如说ComboBox绑定了一个List<Employee>.

1 List < Employee > list = new List < Employee > (){
2 new Employee(){ EmpID = " 111 " ,EmpName = " 1ssssss " },
3 new Employee(){EmpID = " 222 " ,EmpName = " 2dddd " },
4 new Employee(){EmpID = " 333 " ,EmpName = " 3ffff " }
5 };
6 this .comboBox1.ItemsSource = list;
7 this .comboBox1.displayMemberPath = " EmpName " ;

现在希望把ID为333的Employee设为当前选择项。不能像以前那样直接Text="3ffff"设定当前值。

在Siverlight中却有些繁琐。具体的代码：

Employee emp = new Employee() { EmpID = " 333 " ,EmpName = " 3ffff " }; //this.comboBox1.SelectedItem = emp; //这样设不起作用.
List < Employee > list = this .comboBox1.ItemsSource as List < Employee > ;
int flag = - 1 ;
for ( int i = 0 ; i < list.Count; i ++ )
{
if (list[i].EmpID == emp.EmpID && list[i].EmpName == emp.EmpName)
{
flag = i;
break ;
}
}
this .comboBox1.Selectedindex = flag;

到此为止，可以设置ComboBox的当前选择项了。是不是有些绕，为什么不能直接公开一个属性让开发者去设呢？

完整代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Collections;

namespace SilverlightApplication2
{
public partial class Page : UserControl
{
public Page()
{
InitializeComponent();
List<Employee> list = new List<Employee>(){
new Employee(){ EmpID="111",EmpName="1ssssss"},
new Employee(){EmpID="222",EmpName="2dddd"},
new Employee(){EmpID="333",EmpName="3ffff"}
};
this.comboBox1.ItemsSource = list;
this.comboBox1.displayMemberPath = "EmpName";
}

private void btnShow_Click(object sender,RoutedEventArgs e)
{
Employee emp = this.comboBox1.SelectedItem as Employee;
MessageBox.Show(string.Format("EmpID={0},EmpName={1}",emp.EmpID,emp.EmpName));
}

private void btnSet_Click(object sender,RoutedEventArgs e)
{
//this.comboBox1.SelectedItem = emp; //this is not allowed.
Employee emp = new Employee() { EmpID = "333",EmpName = "3ffff" };
List<Employee> list = this.comboBox1.ItemsSource as List<Employee>;
int flag = -1;
for (int i = 0; i < list.Count; i++)
{
if (list[i].EmpID == emp.EmpID && list[i].EmpName == emp.EmpName)
{
flag = i;
break;
}
}
this.comboBox1.Selectedindex = flag;
}
}
public class Employee
{
public string EmpName { get; set; }
public string EmpID { get; set; }
}
}

<UserControl x:Class="SilverlightApplication2.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="400" Height="500">
<StackPanel x:Name="LayoutRoot" Background="White">
<ComboBox x:Name="comboBox1" Width="200" Height="60" Margin="20"></ComboBox>
<Button x:Name="btnShow" Click="btnShow_Click" Content="Get ComboBox SelectItem" Height="60" Width="200" Margin="20"></Button>
<Button x:Name="btnSet" Click="btnSet_Click" Content="Set ComboBox Selectedindex" Height="60" Width="200" Margin="20"></Button>
</StackPanel>
</UserControl>