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我的佈局中有滑動面板。 在第一個孩子中有一個按鈕可以正常工作，但是當我在第二個孩子中添加按鈕時，會拋出NullPointerException異常。 如果我刪除按鈕佈局工作得很好。 我無法理解我做錯了什麼？無法在第二個子項中添加按鈕滑動面板
佈局是這樣的：
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.sothree.slidinguppanel.SlidingUpPanelLayout
xmlns:sothree="http://schemas.android.com/apk/res-auto"
android:id="@+id/sliding_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="bottom"
sothree:umanoPanelHeight="68dp"
sothree:umanoShadowHeight="4dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center|top"
android:text="The Awesome Sliding Up Panel"
android:textSize="16sp" />
<Button
android:id="@+id/toggle_upper"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Upper" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="Edit this" />
<Button
android:id="@+id/toggle_upper2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Upper" />
</LinearLayout>
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
</LinearLayout>
例外：
java.lang.NullPointerException
at android.view.ViewGroup_Delegate.drawShadow(ViewGroup_Delegate.java:74)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:61)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15017)
at android.view.ViewGroup.drawChild_Original(ViewGroup.java:3404)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:53)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at com.sothree.slidinguppanel.SlidingUpPanelLayout.drawChild(SlidingUpPanelLayout.java:1024)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15017)
at android.view.ViewGroup.drawChild_Original(ViewGroup.java:3404)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:53)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15017)
at android.view.ViewGroup.drawChild_Original(ViewGroup.java:3404)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:53)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15017)
at android.view.ViewGroup.drawChild_Original(ViewGroup.java:3404)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:53)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15117)
at android.view.View.draw(View.java:15022)
at android.view.ViewGroup.drawChild_Original(ViewGroup.java:3404)
at android.view.ViewGroup_Delegate.drawChild(ViewGroup_Delegate.java:53)
at android.view.ViewGroup.drawChild(ViewGroup.java:3404)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15117)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:587)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:334)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:688)
at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:677)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:932)
at com.android.tools.idea.rendering.RenderService.createRenderSession(RenderService.java:677)
at com.android.tools.idea.rendering.RenderService.render(RenderService.java:815)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:646)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1700(AndroidLayoutPreviewToolWindowManager.java:82)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7$1.run(AndroidLayoutPreviewToolWindowManager.java:589)
at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:178)
at com.intellij.openapi.progress.ProgressManager.executeProcessUnderProgress(ProgressManager.java:209)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:212)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:171)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7.run(AndroidLayoutPreviewToolWindowManager.java:584)
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$1.run(Alarm.java:327)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)