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I'm developing a Xamarin.Forms app. It works well, but keeps on crashing when the user brings it back from background after opening a few other apps. I'm new to Xamarin and I'm not sure how to debug this issue. This issue is not happening on iOS so far.
SplashActivity.cs:
using System.Threading.Tasks;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Support.V7.App;
using Android.Util;
namespace MyApp.Droid
{
[Activity(Theme = "@style/MyTheme.Splash", MainLauncher = true, NoHistory = true)]
public class SplashActivity : AppCompatActivity
{
static readonly string TAG = "X:" + typeof(SplashActivity).Name;
protected override void OnCreate(Bundle savedInstanceState) // PersistableBundle persistentState
{
base.OnCreate(savedInstanceState); // persistentState
Log.Debug(TAG, "SplashActivity.OnCreate");
}
protected override void OnResume()
{
base.OnResume();
Task startupWork = new Task(() =>
{
Log.Debug(TAG, "Performing some startup work that takes a bit of time.");
Task.Delay(5000); // Simulate a bit of startup work.
Log.Debug(TAG, "Working in the background - important stuff.");
});
startupWork.ContinueWith(t =>
{
Log.Debug(TAG, "Work is finished - start Activity1.");
StartActivity(new Intent(Application.Context, typeof(MainActivity)));
}, TaskScheduler.FromCurrentSynchronizationContext());
startupWork.Start();
}
}
}
MainActivity.cs:
using System;
using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using HockeyApp.Android;
using HockeyApp.Android.Metrics;
using Xamarin.Android.Net; // Keep to make TLS 1.2 work
namespace MyApp.Droid
{
[Activity(Label = "EventingVolunteers.Droid", Icon = "@drawable/icon", Theme = "@style/MyTheme", ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App());
// HockeyApp
CrashManager.Register(this, Constants.HockeyAppID_Android);
MetricsManager.Register(this, Application, Constants.HockeyAppID_Android);
// Push Notifications
RegisterForGCM();
}
private void RegisterForGCM()
{
string senders = Constants.GoogleConsoleProjectId;
Intent intent = new Intent("com.google.android.c2dm.intent.REGISTER");
intent.SetPackage("com.google.android.gsf");
intent.PutExtra("app", PendingIntent.GetBroadcast(this, 0, new Intent(), 0));
intent.PutExtra("sender", senders);
StartService(intent);
}
protected override void OnPause()
{
base.OnPause();
}
protected override void OnResume()
{
base.OnResume();
}
protected override void OnDestroy()
{
base.OnDestroy();
}
}
}
Error message:
java.lang.IllegalStateException: Fragment does not have a view
android.support.v4.app.Fragment$1.onFindViewById()Fragment.java:1933
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1057
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.Fragment.performActivityCreated()Fragment.java:1989
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1092
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.FragmentController.dispatchActivityCreated()FragmentController.java:174
android.support.v4.app.FragmentActivity.onStart()FragmentActivity.java:598
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.n_onStart(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.onStart()FormsAppCompatActivity.java:120
android.app.Instrumentation.callActivityOnStart()Instrumentation.java:1260
android.app.Activity.performStart()Activity.java:6261
android.app.ActivityThread.performLaunchActivity()ActivityThread.java:2389
android.app.ActivityThread.handleLaunchActivity()ActivityThread.java:2490
at android.app.ActivityThread.-wrap11(ActivityThread.java)
android.app.ActivityThread$H.handleMessage()ActivityThread.java:1354
android.os.Handler.dispatchMessage()Handler.java:102
android.os.Looper.loop()Looper.java:148
android.app.ActivityThread.main()ActivityThread.java:5456
java.lang.reflect.Method.invoke(Native Method)
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run()ZygoteInit.java:728
com.android.internal.os.ZygoteInit.main()ZygoteInit.java:618
Xamarin caused by: Java.Lang.IllegalStateException: Fragment does not have a view
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Java.Interop.JniEnvironment.InstanceMethods.CallNonvirtualVoidMethod(JniObjectReference instance, JniObjectReference type, JniMethodInfo method, JniArgumentValue* args)
Java.Interop.JniPeerMembers.JniInstanceMethods.InvokeVirtualVoidMethod(string encodedMember, IJavaPeerable self, JniArgumentValue* parameters)
Android.App.Activity.OnStart()
Xamarin.Forms.Platform.Android.FormsAppCompatActivity.OnStart()
Android.App.Activity.n_OnStart(IntPtr jnienv, IntPtr native__this)
at (wrapper dynamic-method) System.Object:23d8bc20-60cf-4cac-a339-6cc6722e8667 (intptr,intptr)
--- End of managed Java.Lang.IllegalStateException stack trace ---
java.lang.IllegalStateException: Fragment does not have a view
android.support.v4.app.Fragment$1.onFindViewById()Fragment.java:1933
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1057
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.Fragment.performActivityCreated()Fragment.java:1989
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1092
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.FragmentController.dispatchActivityCreated()FragmentController.java:174
android.support.v4.app.FragmentActivity.onStart()FragmentActivity.java:598
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.n_onStart(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.onStart()FormsAppCompatActivity.java:120
android.app.Instrumentation.callActivityOnStart()Instrumentation.java:1260
android.app.Activity.performStart()Activity.java:6261
android.app.ActivityThread.performLaunchActivity()ActivityThread.java:2389
android.app.ActivityThread.handleLaunchActivity()ActivityThread.java:2490
at android.app.ActivityThread.-wrap11(ActivityThread.java)
android.app.ActivityThread$H.handleMessage()ActivityThread.java:1354
android.os.Handler.dispatchMessage()Handler.java:102
android.os.Looper.loop()Looper.java:148
android.app.ActivityThread.main()ActivityThread.java:5456
java.lang.reflect.Method.invoke(Native Method)
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run()ZygoteInit.java:728
com.android.internal.os.ZygoteInit.main()ZygoteInit.java:618
--- End of managed Java.Lang.IllegalStateException stack trace ---
java.lang.IllegalStateException: Fragment does not have a view
android.support.v4.app.Fragment$1.onFindViewById()Fragment.java:1933
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1057
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.Fragment.performActivityCreated()Fragment.java:1989
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1092
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1252
android.support.v4.app.FragmentManagerImpl.moveToState()FragmentManager.java:1234
android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated()FragmentManager.java:2046
android.support.v4.app.FragmentController.dispatchActivityCreated()FragmentController.java:174
android.support.v4.app.FragmentActivity.onStart()FragmentActivity.java:598
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.n_onStart(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.FormsAppCompatActivity.onStart()FormsAppCompatActivity.java:120
android.app.Instrumentation.callActivityOnStart()Instrumentation.java:1260
android.app.Activity.performStart()Activity.java:6261
android.app.ActivityThread.performLaunchActivity()ActivityThread.java:2389
android.app.ActivityThread.handleLaunchActivity()ActivityThread.java:2490
at android.app.ActivityThread.-wrap11(ActivityThread.java)
android.app.ActivityThread$H.handleMessage()ActivityThread.java:1354
android.os.Handler.dispatchMessage()Handler.java:102
android.os.Looper.loop()Looper.java:148
android.app.ActivityThread.main()ActivityThread.java:5456
java.lang.reflect.Method.invoke(Native Method)
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run()ZygoteInit.java:728
com.android.internal.os.ZygoteInit.main()ZygoteInit.java:618
App.xaml.cs:
using System;
using System.Linq;
using Amazon;
using Xamarin.Forms;
namespace MyApp
{
public partial class App : Application
{
public static string AppName { get { return "MyApp"; } }
public static User User { get; set; }
public static UserManager UserManager { get; private set; }
public static VolunteerManager VolunteerManager { get; private set; }
public static SignupManager SignupManager { get; private set; }
static NavigationPage NavPage;
public static bool IsLoggedIn
{
get
{
if (User != null)
return !string.IsNullOrWhiteSpace(User.Email);
else
return false;
}
}
public static Action SuccessfulLoginAction
{
get
{
return new Action(() =>
{
NavPage.Navigation.PopModalAsync();
if (IsLoggedIn)
{
// Update RestService with new token
UserManager = new UserManager(new RestService());
VolunteerManager = new VolunteerManager(new RestService());
SignupManager = new SignupManager(new RestService());
NavPage.Navigation.InsertPageBefore(new VolunteerDashboardPage(), NavPage.Navigation.NavigationStack.First());
NavPage.Navigation.PopToRootAsync();
}
});
}
}
public static Action LogoutAction
{
get
{
return new Action(() =>
{
DependencyService.Get<ICredentialsService>().DeleteCredentials();
App.User = null;
// NavPage.Navigation.PopModalAsync();
NavPage.Navigation.InsertPageBefore(new LoginPage(), NavPage.Navigation.NavigationStack.First());
NavPage.Navigation.PopToRootAsync();
});
}
}
public App()
{
User = new User();
UserManager = new UserManager(new RestService());
VolunteerManager = new VolunteerManager(new RestService());
SignupManager = new SignupManager(new RestService());
// AWS SDK
var loggingConfig = AWSConfigs.LoggingConfig;
loggingConfig.LogMetrics = true;
loggingConfig.LogResponses = ResponseLoggingOption.Always;
loggingConfig.LogMetricsFormat = LogMetricsFormatOption.JSON;
loggingConfig.LogTo = LoggingOptions.SystemDiagnostics;
//AWSConfigs.AWSRegion = "us-east-1";
// Check if login needed
if (DependencyService.Get<ICredentialsService>().DoCredentialsExist())
{
NavPage = new NavigationPage(new VolunteerDashboardPage());
MainPage = NavPage;
// MainPage = new VolunteerDashboardPage();
} else {
NavPage = new NavigationPage(new LoginPage());
MainPage = NavPage;
}
}
protected override void OnStart()
{
// Handle when your app starts
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
// Handle when your app resumes
}
}
}
939
Adding nuget package AndroidX.Fragment version "1.2.5.4" worked for me. Able to reproduce only if i select developer options -> Don't keep activities
170
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