Question

当我尝试更新ListView中插入元素的值时，我没有看到手机上的更改，但是在调试消息中我看到了更改。这是我的代码。

 private void chat_LayoutUpdated(object sender, object e)
    {
        foreach (Message item in chat.Items)
        {
            item.MessageTime = GetRelativeDate(item.MessageDateTime);
            Debug.WriteLine(item.MessageTime); //Display changed value(Delta computed on step before) but on phone screen value didn't change;
        }

    }

GetRelativeDate //长函数，在发出消息时返回当前时间和时间之间的差值。

class Message // Model of chat message
{
    public string MessageText { get; set; }
    public string MessageTime { get; set; } // This value i want to change in ListView.
    public DateTime MessageDateTime { get; set; }
}

XAML

<TextBlock Grid.Column="0"
                FontSize="22"
                Text="{Binding MessageText}" />
                        <TextBlock
                Grid.Column="1"
                Grid.Row="1"
                FontSize="10"
                Text="{Binding MessageTime}" />

P / s也许我需要更具体的东西用作聊天窗口。

无论如何，谢谢你们，我真的很感激任何答案或建议。

Answer 1

需要实施INofityPropertyChanged

MSDN: inotifypropertychanged Example

MSDN文章中的示例：

public class DemoCustomer : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    // This method is called by the Set accessor of each property. 
    // The CallerMemberName attribute that is applied to the optional propertyName 
    // parameter causes the property name of the caller to be substituted as an argument. 
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private DemoCustomer()
    {
    }

    private string customerNameValue = String.Empty;
    public string CustomerName
    {
        get
        {
            return this.customerNameValue;
        }

        set
        {
            if (value != this.customerNameValue)
            {
                this.customerNameValue = value;
                NotifyPropertyChanged();
            }
        }
    }
}

Answer 2

谢谢@ChubosaurusSoftware！。

这里我如何实现该接口可能是一些需要的例子，或者我不太清楚，你可以建议更好的解决方案。

首先添加到使用System.ComponentModel; 然后改变那样的模型。

class Message : INotifyPropertyChanged
{
    public string MessageText { get; set; }
    private string messageTime = String.Empty;
    public string MessageTime
    {
        get { return this.messageTime; }
        set
        {
            if (value != this.messageTime)
            {
                this.messageTime = value;
                NotifyPropertyChanged("MessageTime");
            }
        }
    }
    public DateTime MessageDateTime { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Answer 3

我尝试了这个，它对我有用

List<Model.BeneficiaryItem> oldListItem = listItem;
List<Model.DataType> newListItem = new List<Model.DataType>();

ListView.ItemsSource = newListItem; 


//update the data

for (int i = 0; i < oldListItem.Count; i++)
{
 Model.DataTyep benItem = new Model.DataTyep ();
 // update the individual object  benItem          

newListItem.Add(benItem);
}

ListViewBenList.ItemsSource = newListItem;

更新ListView项目值不起作用Windows Phone 8.1

3 个答案: