渲染XML文件时出错。 它有FragmentTabHost，带有Vertical ScrollView的TabWidget和用于显示标签内容的FrameLayout。而且我在水平方向上使用垂直标签。
以下是布局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/background2"
android:orientation="vertical">
<include
android:id="@+id/toolbar"
layout="@layout/toolbar" />
<android.support.v4.app.FragmentTabHost
android:id="@android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:weightSum="1">
<ScrollView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="0.3">
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</ScrollView>
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="0" />
<FrameLayout
android:id="@+id/realtabcontent"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="0.7" />
</LinearLayout>
</android.support.v4.app.FragmentTabHost>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="@dimen/standard_height"
android:orientation="horizontal"
android:weightSum="1">
<com.custom.FontButton
android:id="@+id/btn_clear"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="0.3"
android:background="@color/toolbar"
android:minHeight="@dimen/standard_height"
android:text="CLEAR"
android:textColor="@color/background"
android:textSize="@dimen/font_18"
app:customFont="@string/font_regular" />
<com.custom.FontButton
android:id="@+id/btn_apply"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="0.7"
android:background="@color/button"
android:elevation="5dp"
android:minHeight="@dimen/standard_height"
android:text="APPLY"
android:textColor="@color/background"
android:textSize="@dimen/font_18"
app:customFont="@string/font_regular" />
</LinearLayout>
</LinearLayout>
这是渲染时抛出的错误 -
java.lang.IllegalStateException: No tab known for tag null
at android.support.v4.app.FragmentTabHost.doTabChanged(FragmentTabHost.java:330)
at android.support.v4.app.FragmentTabHost.onAttachedToWindow(FragmentTabHost.java:280)
at android.view.View.dispatchAttachedToWindow(View.java:14514)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2836)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2843)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2843)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2843)
at android.view.AttachInfo_Accessor.setAttachInfo(AttachInfo_Accessor.java:42)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:232)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:426)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:510)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:498)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:888)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:498)
at com.android.tools.idea.rendering.RenderTask.access$600(RenderTask.java:72)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:610)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderService.runRenderAction(RenderService.java:366)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:629)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$6.run(AndroidDesignerEditorPanel.java:480)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
PS：我已阅读其他帖子，但其中没有一个是有效的，所以请不要将其标记为重复。
编辑：解决方案
问题在于FragmentTabHost，默认情况下，方向设置为TabWidget.HORIZONTAL，无法通过XML修改，这就是IllegalStateException滚动VERTICAL的原因。
要在Fragment或Activity类中解决此问题，我们需要手动设置方向。查看用于设置方向的代码段
TabWidget.setOrientation(TabWidget.VERTICAL);
一旦完成，你就完成了错误！