Xamarin.Android Designer throws java.lang.ClassNotFoundException when using CoordinatorLayout

[tbalcom]

Xamarin.Android Version (eg: 6.0):

9.1.4.2

Operating System & Version (eg: Mac OSX 10.11):

Windows 10 1809

Support Libraries Version (eg: 23.3.0):

28.0.0

Describe your Issue:

Updating Support libraries from 27.0.2.1 to 28.0.0 broke the Xamarin.Android designer ability to render layouts with a CoordinatorLayout.

Steps to Reproduce (with link to sample solution if possible):

Reference Xamarin.Android.Support.Design 28.0.0 and use CoordinatorLayout in a layout then look at the layout using the Xamarin.Android Designer. The same layout renders correctly while referencing Xamarin.Android.Support.Design 27.0.2.1.

The following layout reproduces the error:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">
</android.support.design.widget.CoordinatorLayout>

Include any relevant Exception Stack traces, build logs, adb logs:

Clicking the "Show Error" button in the designer displays:

mono.android.LibraryClassLoader.loadAndConvertClass(LibraryClassLoader.java:89)
mono.android.LibraryClassLoader.findClass(LibraryClassLoader.java:57)
java.lang.ClassLoader.loadClass(ClassLoader.java:424)
java.lang.ClassLoader.loadClass(ClassLoader.java:357)
android.support.design.widget.CoordinatorLayout.setupForInsets(CoordinatorLayout.java:3213)
android.support.design.widget.CoordinatorLayout.(CoordinatorLayout.java:226)
android.support.design.widget.CoordinatorLayout.(CoordinatorLayout.java:201)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

[moljac]

I had similar issues with BottomNavigationView samples.

Classic workarounds like deleting bin/ and ob/ sometimes helped.

If possible please submit minimal sample, so we can speed up investigation.

[Ruud-cb]

Same here but different "solution"
I had to target Android 9 (P) because a dependency FFImageLoading was asking me to change to that target framework (showed as warning). It did work for a while but apparently at some point the designer noticed the change and made it unable to load any layout file.
When I change back to Android 8.1 as targeting platform, I get my designer back.
It now shows a warning at the bottom: "This project contains resources that were not compiled successfully, rendering might be affected". This didn't show up when I was targeting Android 9.

The layouts that were complaining with this error:
android.support.design.widget.TextInputLayout => I was testing with this one, when I removed this from the layout, the warning disappeared but the remaining elements (ImageView and Button) did not show up, so it was still a death end,
android.support.v4.widget.DrawerLayout
android.support.design.widget.NavigationView

I am targeting the following nuget packages directly. This due complaining of version conflicts when I tried to install Xamarin.FFImageLoading, it has v 27.0.2.1 locked. So after installing these packages manually, I could install that package.

• Xamarin.Android.Support.Design v28.0.0
• Xamarin.Android.Support.CustomTabs v28.0.0
• Xamarin.Android.Support.v7.CardView v28.0.0
• Xamarin.Essentials v1
• Xamarin.FFImageLoading v2.4.4.859

[tbalcom]

This is still a problem with Visual Studio 2017 15.9.5/Xamarin.Android 9.1.5.0. Deleting bin & obj folders changes nothing. Upgrading Android Support packages from 27.0.2.1 to 28.0.0.0 triggers the problem. The problem is most likely not specific to CoordinatorLayout. It seems to be triggered by many Support widgets (Toolbar, TextInputLayout, CoordinatorLayout, etc.). The same project can render layouts without any support widgets fine.

It's pretty simple to reproduce:

1. Create a new Android project using the Visual Studio 2017 "Single View App" template with Minimum Android version set to: Android 5.0 Lollipop
2. Build the project. The Android designer correctly renders activity_main as expected.
3. Change the Target Framework to Android 9.0 (Pie).
4. Rebuild the project. The Android designer is still correctly rendering activity_main.
5. Update Xamarin.Android.Support.Design from 27.0.2.1 to 28.0.0.0 using the NuGet GUI.
6. Rebuild the project. The Android designer now fails to render activity_main.
7. Downgrade Xamarin.Android.Support.Design from 28.0.0.0 to 27.0.2.1 using the NuGet GUI.
8. Rebuild the project. The Android designer correctly renders activity_main again.

[Ruud-cb]

Just a little hint for @tbalcom 's answer: I am targeting android 8.1 in combination with Xamarin.Android.Support.Design 28.0.0.0, so it seems that the combination of Android Pie and v28.0.0.0 creates problems. Targeting android 8.1 it only gives a warning I mentioned earlier.

So this way at least can develop against the new support design version, just have to increase the target once a fix is in place.

[moljac]

@tbalcom I tried to reproduce your steps on Mac with Internal Preview (VS4Mac) and no issues.
I will try to reproduce with VS2017 on Windows on Monday. I see that the templates do differ.

[Ruud-cb]

@moljac keep in mind you should do the clean build, remove obj,bin folder things and so on. Because as I remember it, at first it looked oke, after some time it produced errors.

[DearXxGitHub]

I had the same problem on Windows

I have the same problem on Windows. All Visual Studio updates have been applied. Dropping target API to 8.1 solves the designer issue.

[hunter-digital]

Can confirm this issue. Designer became broken on updating to support 28 and targeting Pie.

[hunter-digital]

@moljac Is there any status update on this issue? Is there any way that we could participate in the fixing of this issue? Android designer going down on so many of my views is gonna kill my team.

[Ruud-cb]

Guys due installing packages which require me to upgrade to V9 of android I cannot do any designing at this moment. PLEASE address this issue. Is it a Visual Studio issue? Xamarin related? DOes 28.0.1 fix the problem?

[moljac]

@Ruud-cb @hunter-digital @tbalcom @DearXxGitHub @RonPeters
can you send me detailed info about Visual Studio Version, Xamarin.Android and Xamarin.Android Designer please?