![](/img/trans.png)
[英]android.support.v7.widget.RecyclerView$ViewHolder.shouldIgnore()' on a null object reference
[英]Default android RecyclerView ViewHolder NPE shouldIgnore()
我正在使用來自 android 工作室的默認列表片段,當我在我的活動中使用它時它會崩潰。 我看到了類似的錯誤,但沒有發現有用的修復(我嘗試更改適配器 getItemCount 和 recyclerView layoutManager)
崩潰日志:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean androidx.recyclerview.widget.RecyclerView$ViewHolder.shouldIgnore()' on a null object reference
at androidx.recyclerview.widget.RecyclerView.findMinMaxChildLayoutPositions(RecyclerView.java:4311)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:4045)
at androidx.recyclerview.widget.RecyclerView.onMeasure(RecyclerView.java:3534)
at android.view.View.measure(View.java:26415)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:7845)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
片段 onCreateView:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_identity_list, container, false);
if (view instanceof RecyclerView)
{
RecyclerView recyclerView = (RecyclerView) view;
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(new IdentityRecyclerViewAdapter(DummyContent.ITEMS, mListener));
}
return view;
}
片段身份列表:
<androidx.recyclerview.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/identityRecycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutManager="LinearLayoutManager"
tools:context=".activity.IdentityFragment"
tools:listitem="@layout/fragment_identity" />
回收器視圖適配器:
public class IdentityRecyclerViewAdapter extends RecyclerView.Adapter<IdentityRecyclerViewAdapter.IdentityViewHolder>
{
private final List<DummyItem> mValues;
private final IdentityListFragmentInteractionListener mListener;
public IdentityRecyclerViewAdapter(List<DummyItem> items, IdentityListFragmentInteractionListener listener)
{
mValues = items;
mListener = listener;
}
@Override
public IdentityViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fragment_identity, parent, false);
return new IdentityViewHolder(view);
}
@Override
public int getItemCount()
{
return mValues.size();
}
public class IdentityViewHolder extends RecyclerView.ViewHolder
{
public final View mView;
public final TextView mIdView;
public final TextView mContentView;
public DummyItem mItem;
public IdentityViewHolder(View view)
{
super(view);
mView = view;
mIdView = view.findViewById(R.id.item_number);
mContentView = view.findViewById(R.id.content);
}
}
}
創建活動:
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.add(R.id.identityList, IdentityFragment.newInstance(ListType.ALL), "List");
transaction.commit();
}
dummyContent.ITEMS 只是 25 個元素“項目 i”的列表。
修復方法是將回收站視圖放在框架布局中。
注意:我還在 Activity#onCreate 中對片段進行了充氣,盡管它已經使用 xml 自動充氣,這導致了第一個后面的“幻影”列表。
片段身份列表:
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".activity.IdentityFragment">
<!--PUT RECYCLER VIEW IN A FRAME LAYOUT-->
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/identityRecycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:listitem="@layout/fragment_identity" />
</FrameLayout>
活動 onCreateView
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_identity_list, container, false);
RecyclerView recyclerView = view.findViewById(R.id.identityRecycler);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(new IdentityRecyclerViewAdapter(DummyContent.ITEMS, mListener))
return view;
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.