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通过值C#从数组中多选ListBox项

[英]Multi Selecting ListBox Items From Array by Value C#

我想从数组中多选项目,

出于某种原因,此代码将引发NullReferenceException异常:

        int[] players = Playerss.GetAllPlayersIDbyMovieID(movie);
        foreach (int playerID in players)
        {
            PlayersListBox.Items.FindByValue(playerID.ToString()).Selected = true;
        }

当我改用此代码时,它可以工作,但只会保留最后选择的选项:

            int[] players = Playerss.GetAllPlayersIDbyMovieID(movie);
            foreach (int playerID in players)
            {
                PlayersListBox.SelectedValue += playerID.ToString();
            }

ASP .NET文件:

<asp:ListBox ID="PlayersListBox" runat="server" 
            SelectionMode="Multiple"
                   DataSourceID="PlayersAccessDataSource"
                      DataTextField="Player" 
                      DataValueField="PlayerID"           

            ></asp:ListBox> 
Playerss.GetAllPlayersIDbyMovieID(movie); 

您可能会收到一个空异常请求,因为在Playerss.GetAllPlayersIDbyMovieID(movie)方法的结果中某处有一个选项在PlayersListBox.Items中不可用

在尝试为不存在的对象设置属性值之前,可以通过检查null来解决此问题。

int[] players = Playerss.GetAllPlayersIDbyMovieID(movie);
    foreach (int playerID in players)
    {
        var player = PlayersListBox.Items.FindByValue(playerID.ToString());
        if (player != null) 
        {
            player.Selected = true;
        }
    }

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