我在尝试显示回收 View 时出现以下异常:
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:1216)
at android.view.View.onDrawScrollBars(View.java:13900)
at android.view.View.draw(View.java:16275)
at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:2440)
at android.view.View.updateDisplayListIfDirty(View.java:15192)
at android.view.View.getDisplayList(View.java:15215)
at android.view.View.draw(View.java:15990)
at android.view.ViewGroup.drawChild(ViewGroup.java:3708)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3502)
at android.view.View.draw(View.java:16272)
at android.view.View.updateDisplayListIfDirty(View.java:15192)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:362)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3692)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3671)
at android.view.View.updateDisplayListIfDirty(View.java:15152)
at android.view.View.getDisplayList(View.java:15215)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:307)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:313)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:352)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2811)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2634)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2222)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1230)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6726)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:777)
at android.view.Choreographer.doCallbacks(Choreographer.java:590)
at android.view.Choreograph
我的 xml 是这样的:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
style="@style/global_screen_linear_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:id="@+id/lilAdvancedSearchParent"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/gray_general"
android:gravity="center_vertical"
android:orientation="horizontal"
android:padding="10dp" >
<LinearLayout
android:id="@+id/lilAdvancedSearch"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="6"
android:gravity="center_vertical" >
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/arrow_white" />
<TextView
android:id="@+id/txvAvencedSearch"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:layout_weight="4.5"
android:text="@string/global_fragment_advenced_search"
android:textColor="@color/white"
android:textSize="@dimen/global_screen_layout_text_view_advenced_search"
android:textStyle="bold" />
</LinearLayout>
<EditText
android:id="@+id/edtSearch"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="9"
android:drawableLeft="@drawable/navigation_search"
android:ems="10"
android:imeOptions="actionSearch"
android:inputType="text"
android:textColor="@color/white"
android:textColorHint="@color/white"
android:textSize="15sp" >
<requestFocus />
</EditText>
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/my_recycler_view"
android:layout_width="match_parent"
android:layout_height="800dp"
android:scrollbars="vertical" >
</android.support.v7.widget.RecyclerView>
</LinearLayout>
我的java代码是这样的:
public class TendersFragment extends BaseFragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.global_screen_layout, container, false);
initUI(v);
initListeners();
setEditSearchHint(getString(R.string.tenders_fragment_search_tenders));
setAdvancedSearchBackground(getResources().getColor(R.color.green_general));
return v;
}
@Override
protected void initUI(View view) {
lsvTendersJobsMessages = (ListView) view.findViewById(R.id.lsvGlobal);
mRecyclerView = (RecyclerView) view.findViewById(R.id.my_recycler_view);
setAdapterForListview(lsvTendersJobsMessages);
edtSearch = (EditText) view.findViewById(R.id.edtSearch);
txvAdvencedSearch = (TextView) view.findViewById(R.id.txvAvencedSearch);
lilAdvancedSearch = (LinearLayout) view.findViewById(R.id.lilAdvancedSearch);
lilAdvancedSearchParent = (LinearLayout) view.findViewById(R.id.lilAdvancedSearchParent);
}
@Override
protected void setAdapterForListview(ListView lsv) {
mRecyclerView.setHasFixedSize(true);
mLinearLayoutManager = new LinearLayoutManager(getActivity());
mLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mLinearLayoutManager);
ArrayList<ItemType> arlItems = new ArrayList<ItemType>();
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
arlItems.add(ItemType.MAIN_ITEM);
// specify an adapter (see also next example)
mainItemAdapter = new MainItemAdapter(arlItems, getActivity());
mRecyclerView.setAdapter(mainItemAdapter);
}
@Override
protected void onServiceConnected() {
// TODO Auto-generated method stub
}
protected void initListeners() {
final AdvancedSearchFragment advancedSearchFragment = new AdvancedSearchFragment();
Bundle bundle = new Bundle();
bundle.putInt(FragmentConst.BUNDLE_KEY_INT_WHICH_FRAGMENT,FragmentConst.TENDERS_ID);
advancedSearchFragment.setArguments(bundle);
lilAdvancedSearch.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
getActivity().getSupportFragmentManager().beginTransaction()
.add(android.R.id.content,advancedSearchFragment).addToBackStack(null)
.commit();
}
});
}
}
我也尝试将回收 View 的 layout_height 设置为 match_parent 和 wrap_contant 但我仍然遇到相同的错误
最佳答案
这是我最终解决这个问题的方法。
我从 RecyclerView 声明中删除了 android:scrollbars="vertical":
<android.support.v7.widget.RecyclerView
android:id="@+id/task_recycler_view"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
关于android - 回收 View - java.lang.NullPointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30284983/