在父按钮上添加子按钮单击Xamarin.forms

本文关键字：按钮 单击 Xamarin forms 添加 | 更新日期: 2023-09-27 18:14:38

我一直在尝试在Android的按钮点击上添加一个标签视图到Stacklayout。但是它抛出空指针异常。下面是我想要达到的目标。谁能告诉我如何在xamarin.forms

中实现这一点?

Xamarin的。c#中的窗体代码

 StackLayout parent= new StackLayout ();
 Button add= new Button
        {
            HorizontalOptions=LayoutOptions.End,
            BackgroundColor=Xamarin.Forms.Color.White,
            Text="ADD",
            TextColor=Xamarin.Forms.Color.Maroon,
        };
 add.Clicked += OnButtonClicked;
 
 Label firstLabel = new Label
        {
            Text = "Label 1",
            HorizontalOptions = LayoutOptions.StartAndExpand,
            TextColor=Xamarin.Forms.Color.FromHex("#000000")
        };
 parent.Children.Add(add);
 parent.Children.Add(firstLabel );

在ButtonClick中添加标签

 void OnButtonClicked(object sender, EventArgs e)
 {
   Label secondLabel = new Label
        {
            Text = "Label 1",
            HorizontalOptions = LayoutOptions.StartAndExpand,
            TextColor=Xamarin.Forms.Color.FromHex("#000000")
        };
  parent.Children.Add(secondLabel ); 
}

Thanks in Advance

在父按钮上添加子按钮单击Xamarin.forms

你的代码是这样工作的…一个微小的变化-使parent一个类字段，所以它从OnButtonClicked

引用

确保您更新了解决方案包，以便您拥有最新的Xamarin.Forms。总是在解决方案级别更新包，这样就不会出现版本冲突

此版本经过测试并在iOS上运行:

public class LabelPage: ContentPage
    {
        StackLayout parent = null;
        public LabelPage ()
        {
            parent = new StackLayout ();
            Button add = new Button {
                HorizontalOptions = LayoutOptions.End,
                BackgroundColor = Xamarin.Forms.Color.White,
                Text = "ADD",
                TextColor = Xamarin.Forms.Color.Maroon,
            };
            add.Clicked += OnButtonClicked;
            Label firstLabel = new Label {
                Text = "Label 1",
                HorizontalOptions = LayoutOptions.StartAndExpand,
                TextColor = Xamarin.Forms.Color.FromHex ("#000000")
            };
            parent.Children.Add (add);
            parent.Children.Add (firstLabel); 
            Content = parent;
        }
        void OnButtonClicked (object sender, EventArgs e)
        { 
            Label secondLabel = new Label {
                Text = "Label 1",
                HorizontalOptions = LayoutOptions.StartAndExpand,
                TextColor = Xamarin.Forms.Color.FromHex ("#000000")
            };
            parent.Children.Add (secondLabel); 
            //UpdateChildrenLayout ();
        }
    }
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