Question:
Every time I open a layout file the preview doesn't appear and an error appears in the event log. It's not a specific layout, it's all layouts.
There's an identical question in the English version, but it's been a year old and it's unanswered.
Mistake:
com/xxxx/xxxx/activity/R$mipmap
java.lang.ClassFormatError: com/xxxx/xxxx/activity/R$mipmap
at java.lang.Class.getDeclaredClasses0(Native Method)
at java.lang.Class.getDeclaredClasses(Class.java:1867)
at org.jetbrains.android.uipreview.ViewLoader.parseClass(ViewLoader.java:562)
at org.jetbrains.android.uipreview.ViewLoader.loadAndParseRClass(ViewLoader.java:546)
at org.jetbrains.android.uipreview.ViewLoader.loadAndParseRClassSilently(ViewLoader.java:502)
at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadAndParseRClass(LayoutlibCallbackImpl.java:663)
at com.android.tools.idea.rendering.RenderTask.<init>(RenderTask.java:153)
at com.android.tools.idea.rendering.RenderService.createTask(RenderService.java:198)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:649)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1700(AndroidLayoutPreviewToolWindowManager.java:80)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7$1.run(AndroidLayoutPreviewToolWindowManager.java:594)
at com.intellij.openapi.progress.impl.CoreProgressManager$2.run(CoreProgressManager.java:142)
at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:446)
at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:392)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:54)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:127)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7.run(AndroidLayoutPreviewToolWindowManager.java:589)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:337)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:327)
at com.intellij.util.ui.update.MergingUpdateQueue$3.run(MergingUpdateQueue.java:271)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:286)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:244)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:234)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:352)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Update:
I changed the android version in the design preview as said in this post, it didn't solve it.
Update 2:
I looked for updates to Android Studio, I reinstalled it and installed all packages by SDK Manager again, it didn't solve it either.
Answer:
After hours of trying, I created a new project in Android Studio to copy the project files to a new project (my last hope). Once the project was created, the render returned to work normally. It's probably some bug from Android Studio, where I've already reported it.