在 onOptionsItemSelected 中创建 recyclerview 而不是在 activity 中的 onCreate
Create recyclerview in onOptionsItemSelected and not onCreate in activity
我有一个recyclerview，它不在onCreate 中，而是在onOptionsItemSelected 中。原因如下：当我单击选项菜单中的某个项目时，我会在底部显示 sheet，请参阅：(google specs and the library)。该库采用 xml 布局，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，出现此异常：
java.lang.NullPointerException: Attempt to invoke virtual method
'boolean
android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()'
on a null object reference
at android.support.v7.widget.RecyclerView.computeVerticalScrollRange(RecyclerView.java:1545)
at android.view.View.onDrawScrollBars(View.java:12943)
at android.view.View.draw(View.java:15237)
at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3037)
at android.view.View.updateDisplayListIfDirty(View.java:14167)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15234)
at android.view.View.updateDisplayListIfDirty(View.java:14167)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.support.v4.widget.DrawerLayout.drawChild(DrawerLayout.java:1089)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.draw(View.java:15234)
at android.widget.FrameLayout.draw(FrameLayout.java:598)
at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2650)
at android.view.View.updateDisplayListIfDirty(View.java:14167)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:273)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:279)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:318)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2530)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2352)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1982)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreo
所以我的问题是：除了 activity 的 onCreate 或片段的 onCreateView 之外，如何在其他任何地方创建 recyclerview？
非常感谢任何帮助。谢谢。
下面是我创建recyclerview的过程：首先我实例化底部sheet。请参阅下面的代码
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，我创建了回收视图。请参阅下面的代码
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sheet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>
//error caused here
不直接。如果是，您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，因此请首先确保您使用的是最新的 recyclerview-v7 (22.2.1)，在如果您被 RecyclerView 错误绊倒。
事实上，is (or was) a bug with RecyclerView that mimics your stack trace, tied to your having the android:scrollbars attribute. That bug was with the IDE rendering code; this bug本身就是RecyclerView。因此，如果您移至 22.2.1 后问题仍然存在，请尝试删除 android:scrollbars，看看是否有帮助。请注意，如果它未在 22.2.1 中修复，我怀疑它是否会被修复，因为 Google 拒绝了第二个错误报告。
我有一个recyclerview，它不在onCreate 中，而是在onOptionsItemSelected 中。原因如下：当我单击选项菜单中的某个项目时，我会在底部显示 sheet，请参阅：(google specs and the library)。该库采用 xml 布局，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，出现此异常：
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()' on a null object reference at android.support.v7.widget.RecyclerView.computeVerticalScrollRange(RecyclerView.java:1545) at android.view.View.onDrawScrollBars(View.java:12943) at android.view.View.draw(View.java:15237) at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3037) at android.view.View.updateDisplayListIfDirty(View.java:14167) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.draw(View.java:15234) at android.view.View.updateDisplayListIfDirty(View.java:14167) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.support.v4.widget.DrawerLayout.drawChild(DrawerLayout.java:1089) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.updateDisplayListIfDirty(View.java:14162) at android.view.View.getDisplayList(View.java:14189) at android.view.View.draw(View.java:14959) at android.view.ViewGroup.drawChild(ViewGroup.java:3405) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198) at android.view.View.draw(View.java:15234) at android.widget.FrameLayout.draw(FrameLayout.java:598) at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2650) at android.view.View.updateDisplayListIfDirty(View.java:14167) at android.view.View.getDisplayList(View.java:14189) at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:273) at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:279) at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:318) at android.view.ViewRootImpl.draw(ViewRootImpl.java:2530) at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2352) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1982) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767) at android.view.Choreographer.doCallbacks(Choreographer.java:580) at android.view.Choreographer.doFrame(Choreographer.java:550) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreo
所以我的问题是：除了 activity 的 onCreate 或片段的 onCreateView 之外，如何在其他任何地方创建 recyclerview？
非常感谢任何帮助。谢谢。
下面是我创建recyclerview的过程：首先我实例化底部sheet。请参阅下面的代码
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，我创建了回收视图。请参阅下面的代码
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sheet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>
//error caused here
不直接。如果是，您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，因此请首先确保您使用的是最新的 recyclerview-v7 (22.2.1)，在如果您被 RecyclerView 错误绊倒。
事实上，is (or was) a bug with RecyclerView that mimics your stack trace, tied to your having the android:scrollbars attribute. That bug was with the IDE rendering code; this bug本身就是RecyclerView。因此，如果您移至 22.2.1 后问题仍然存在，请尝试删除 android:scrollbars，看看是否有帮助。请注意，如果它未在 22.2.1 中修复，我怀疑它是否会被修复，因为 Google 拒绝了第二个错误报告。