Question

我正在使用Xamarin表单（PCL）构建跨平台应用程序。一切都很好，但是当我使用TabbedPage并添加子项时，我在Android项目的MainActivity.cs中得到以下异常：

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()[0x0000c] in < 896ad1d315ca4ba7b117efb8dacaedcf >:0
   at Java.Interop.JniEnvironment + InstanceMethods.CallVoidMethod(Java.Interop.JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue * args)[0x00069] in < 6cd960837cc24c26bab2a0a29b597627 >:0
   at Android.Runtime.JNIEnv.CallVoidMethod(System.IntPtr jobject, System.IntPtr jmethod, Android.Runtime.JValue * parms)[0x0000e] in < 952e88faf9b94435845932f104eb293a >:0
   at Android.Support.Design.Widget.TabLayout.SetupWithViewPager(Android.Support.V4.View.ViewPager viewPager)[0x00060] in < 12ef52c9fdb344f58cbdf75db3fa86d8 >:0
   at Xamarin.Forms.Platform.Android.AppCompat.TabbedPageRenderer.OnChildrenCollectionChanged(System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)[0x00085] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\TabbedPageRenderer.cs:273
   at Xamarin.Forms.Platform.Android.AppCompat.TabbedPageRenderer.OnElementChanged(Xamarin.Forms.Platform.Android.ElementChangedEventArgs`1[TElement] e)[0x00114] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\TabbedPageRenderer.cs:175
   at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].SetElement(TElement element)[0x000f4] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\VisualElementRenderer.cs:196
   at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].Xamarin.Forms.Platform.Android.IVisualElementRenderer.SetElement(Xamarin.Forms.VisualElement element)[0x00027] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\VisualElementRenderer.cs:137
   at Xamarin.Forms.Platform.Android.Platform.CreateRenderer(Xamarin.Forms.VisualElement element)[0x0001f] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\Platform.cs:289
   at Xamarin.Forms.Platform.Android.AppCompat.Platform.AddChild(Xamarin.Forms.Page page, System.Boolean layout)[0x00015] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\Platform.cs:250
   at Xamarin.Forms.Platform.Android.AppCompat.Platform.SetPage(Xamarin.Forms.Page newRoot)[0x00089] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\Platform.cs:239
   at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.InternalSetPage(Xamarin.Forms.Page page)[0x0009b] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\FormsAppCompatActivity.cs:382
   at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.SetMainPage()[0x00000] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\FormsAppCompatActivity.cs:452
   at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.LoadApplication(Xamarin.Forms.Application application)[0x00183] in C:\BuildAgent3\work\ca3766cfc22354a1\Xamarin.Forms.Platform.Android\AppCompat\FormsAppCompatActivity.cs:136
   at App1.Droid.MainActivity.OnCreate(Android.OS.Bundle bundle)[0x000ac] in ........Visual Studio 2017\Projects\App1\App1\App1.Android\MainActivity.cs:42
    -- - End of managed Java.Lang.ClassCastException stack trace-- -
    java.lang.ClassCastException: android.widget.FrameLayout cannot be cast to android.widget.ImageView
at android.support.design.widget.TabLayout$TabView.update(TabLayout.java:1531)

at android.support.design.widget.TabLayout$TabView.setTab(TabLayout.java:1484)

at android.support.design.widget.TabLayout$TabView.access$700(TabLayout.java:1348)

at android.support.design.widget.TabLayout.createTabView(TabLayout.java:799)

at android.support.design.widget.TabLayout.newTab(TabLayout.java:500)

at android.support.design.widget.TabLayout.populateFromPagerAdapter(TabLayout.java:773)

at android.support.design.widget.TabLayout.setPagerAdapter(TabLayout.java:764)

at android.support.design.widget.TabLayout.setupWithViewPager(TabLayout.java:716)

at md58adf3f2592a7497b73592b5e766304c2.MainActivity.n_onCreate(Native Method)

at md58adf3f2592a7497b73592b5e766304c2.MainActivity.onCreate(MainActivity.java:29)

at android.app.Activity.performCreate(Activity.java:6237)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)

at android.app.ActivityThread.- wrap11(ActivityThread.java)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)

at android.os.Handler.dispatchMessage(Handler.java:102)

at android.os.Looper.loop(Looper.java:148)

at android.app.ActivityThread.main(ActivityThread.java:5417)

at java.lang.reflect.Method.invoke(Native Method)

at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

MainActivity.cs

             [Activity(Label = "App1", Icon = "@drawable/icon", 
                  Theme = "@style/MainTheme", MainLauncher = false, 
                     ConfigurationChanges = ConfigChanges.ScreenSize | 
                  ConfigChanges.Orientation)]
                    public class MainActivity : 
               global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
      {

    protected override void OnCreate(Bundle bundle)
    {

        TabLayoutResource = Resource.Layout.Tabbar;
        ToolbarResource = Resource.Layout.Toolbar;

        base.OnCreate(bundle);
        #region Resolver Init
        SimpleContainer container = new SimpleContainer();
        container.Register<IDevice>(t => AndroidDevice.CurrentDevice);
        container.Register<IDisplay>(t => t.Resolve<IDevice>().Display);
        container.Register<INetwork>(t => t.Resolve<IDevice>().Network);

        Resolver.SetResolver(container.GetResolver());
        #endregion



        global::Xamarin.Forms.Forms.Init(this, bundle);
        try
        {
            LoadApplication(new App());
        }
        catch (Exception ex)
        {

        }


    }




}

App.cs

        public App()
        {
        InitializeComponent();
            MainPage = new HomeScreenTabbed()
            {
                BarBackgroundColor = Color.FromHex("#5C8BF6")
            };

         }

HomeScreenTabbed.cs

          public HomeScreenTabbed()
          {            
             InitializeComponent();
             Xamarin.Forms.NavigationPage.SetHasNavigationBar(this, false);
             try
             {
                Children.Add(new ListViewPage1());
                Children.Add(new TabbedPageFirst());
             }
             catch (Exception ex)
             {
                 Device.BeginInvokeOnMainThread(() =>
                 {
                     DisplayAlert("Exception in  RelativeLayout.Children.Add 
                     CreateUserSection", ex.ToString(), "ok");
                 });
             }
           }

当2个添加儿童行被推荐时，没有问题。 ListViewPage1和TabbedPageFirst不包含任何代码，而不是创建它们时的代码。测试在模拟器Android 6.0 - API 23上执行。 Visual Studio Enterprise 2017 15.3.3

有什么想法吗？

非常感谢！

Answer 1

像这样在App.Cs文件中进行更改

  public App()
    {
        InitializeComponent();
        MainPage =new NavigationPage(new HomeScreenTabbed())
        {
            BarBackgroundColor = Color.FromHex("#5C8BF6")
        };

     }

Xamarin表单：TabbedPage问题。添加子项时Android项目中的主Activity.cs中的异常

1 个答案: