Question

我有一个在onCreate中找不到的recyclelerview，但在onOptionsItemSelected中找不到。原因如下：当我点击选项菜单中的某个项目时，我会显示一个底部工作表，请参阅：（google specs和library）。该库采用xml-layout，这是我的recyclerview所在的位置。问题是，当我将布局管理器附加到recyclerview时，我得到了这个例外：

java.lang.NullPointerException：尝试调用虚方法＆＃39;布尔 android.support.v7.widget.RecyclerView $ LayoutManager.canScrollVertically（）＆＃39; 在null对象引用上在android.support.v7.widget.RecyclerView.computeVerticalScrollRange（RecyclerView.java:1545）在android.view.View.onDrawScrollBars（View.java:12943）在android.view.View.draw（View.java:15237）在android.support.v7.widget.RecyclerView.draw（RecyclerView.java:3037）在android.view.View.updateDisplayListIfDirty（View.java:14167）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.draw（View.java:15234）在android.view.View.updateDisplayListIfDirty（View.java:14167）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.support.v4.widget.DrawerLayout.drawChild（DrawerLayout.java:1089）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.updateDisplayListIfDirty（View.java:14162）在android.view.View.getDisplayList（View.java:14189）在android.view.View.draw（View.java:14959）在android.view.ViewGroup.drawChild（ViewGroup.java:3405）在android.view.ViewGroup.dispatchDraw（ViewGroup.java:3198）在android.view.View.draw（View.java:15234）在android.widget.FrameLayout.draw（FrameLayout.java:598）在com.android.internal.policy.impl.PhoneWindow $ DecorView.draw（PhoneWindow.java:2650）在android.view.View.updateDisplayListIfDirty（View.java:14167）在android.view.View.getDisplayList（View.java:14189）在android.view.ThreadedRenderer.updateViewTreeDisplayList（ThreadedRenderer.java:273）在android.view.ThreadedRenderer.updateRootDisplayList（ThreadedRenderer.java:279）在android.view.ThreadedRenderer.draw（ThreadedRenderer.java:318）在android.view.ViewRootImpl.draw（ViewRootImpl.java:2530）在android.view.ViewRootImpl.performDraw（ViewRootImpl.java:2352）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1982）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1061）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:5885）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:767）在android.view.Choreographer.doCallbacks（Choreographer.java:580）在android.view.Choreographer.doFrame（Choreographer.java:550）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreo

所以我的问题是：除了onCreate of activity或onCreateView of fragment之外，如何在其他任何地方创建一个recyclerview？

非常感谢任何帮助。感谢。

以下是我创建recyclerview的过程：首先我实例化底部工作表。见下面的代码

private BottomSheetLayout bottomSheet;

 @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ...

        bottomSheet = (BottomSheetLayout) findViewById(R.id.bottomsheet);
}

在onOptionsItemSelected中，我创建了recyclerview。见下面的代码

List<BottomSheetData> mCategoryList = new ArrayList<>();

BottomSheetAdapter bottomAdapter = new BottomSheetAdapter(mCategoryList); //Recyclerview adapter

RecyclerView mRecyclerView = (RecyclerView) bottomSheet.findViewById(R.id.recyclerView);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
mRecyclerView.setLayoutManager(new LinearLayoutManager(this)); //error caused here 
mRecyclerView.setAdapter(bottomAdapter);

这是我的底部工作表布局

<?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:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FAF9F7">

    <android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:cacheColorHint="@android:color/transparent"
        android:clipToPadding="false"
        android:scrollbars="vertical"
        />

</LinearLayout>

Answer 1

//error caused here

不直接。如果是，你会在堆栈跟踪中看到它。

现在，您的行号与the RecyclerView source code的master分支不匹配，因此请确保您使用最新的recyclerview-v7（22.2.1），以防万一正在绊倒一个RecyclerView错误。

实际上，is (or was) a bug with RecyclerView模仿了您的堆栈跟踪，与您拥有android:scrollbars属性相关联。该错误与IDE呈现代码有关; this bug本身就是RecyclerView。因此，如果移至22.2.1时问题仍然存在，请尝试删除android:scrollbars，看看是否有帮助。请注意，如果它在22.2.1中没有修复，我怀疑它是否会被修复，因为Google拒绝了第二个错误报告。

在onOptionsItemSelected中创建recyclerview，而不是在活动

1 个答案: