В нашем приложении есть ViewPager с FragmentPagerAdapter
, который содержит три фрагмента. Два из этих фрагментов состоят из Recyclerview для каждого из них.
Первая страница (фрагмент без ViewPager) отображается правильно. Однако, когда ViewPager пытается предварительно загрузить следующую страницу (RecyclerView), приложение вылетает из-за NullPointerException
со следующим журналом:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$ViewHolder.shouldIgnore()' on a null object reference
at android.support.v7.widget.RecyclerView.findMinMaxChildLayoutPositions(RecyclerView.java:2839)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2626)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3011)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1626)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1000)
at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:710)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:724)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:907)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:15684)
at android.view.ViewGroup.layout(ViewGroup.java:4981)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2186)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1920)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1106)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6018)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:792)
at android.view.Choreographer.doCallbacks(Choreographer.java:596)
at android.view.Choreographer.doFrame(Choreographer.java:557)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:778)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
Здесь, как объявлен ViewPager:
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(fragment1, "fragment1");
adapter.addFrag(fragment2, "fragment2");
adapter.addFrag(fragment3, "fragment3");
viewPager.setAdapter(adapter);
И адаптер:
private class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
Поскольку код из обоих RecyclerView длинный и отличается для каждой страницы, я действительно не знаю, какая часть релевантна, поэтому я не буду давать какой-либо образец. Не стесняйтесь обращаться к определенной части, если считаете, что это может быть полезно для устранения проблемы.
Единственное, что я могу вам сказать, это то, что если я хочу, чтобы он работал, я должен прокомментировать вызов для каждого из setAdapter
из обоих RecylerView.
EDIT: здесь код для второй страницы.
public class MyFragment extends Fragment {
RecyclerView recyclerView;
GridAdapter gridAdapter;
public GridAdapter getGridAdapter() {
return gridAdapter;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View v = inflater.inflate(R.layout.our_layout, container, false);
recyclerView = (RecyclerView) v.findViewById(R.id.recycler_view);
gridLayoutManager.setSmoothScrollbarEnabled(true);
recyclerView.setLayoutManager(gridLayoutManager);
recyclerView.setHasFixedSize(true);
return v;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
ArrayList<Model> model = getArguments().getParcelableArrayList("extra");
if (model != null && model.size() != 0) {
gridAdapter = new GridAdapter(model);
recyclerView.setAdapter(gridAdapter);
}
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser && isResumed()){
onResume();
}
}
@Override
public void onResume() {
super.onResume();
if (!getUserVisibleHint())
return;
}
public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spanCount;
private int spacingLeft;
private int spacingRight;
private int spacingTop;
private int spacingBottom;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacingLeft, int spacingTop, int spacingRight, int spacingBottom, boolean includeEdge) {
this.spanCount = spanCount;
this.spacingLeft = spacingLeft;
this.spacingRight = spacingRight;
this.spacingTop = spacingTop;
this.spacingBottom = spacingBottom;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view); // item position
int column = position % spanCount; // item column
if (includeEdge) {
outRect.left = spacingLeft - column * spacingLeft / spanCount; // spacing - column * ((1f / spanCount) * spacing)
outRect.right = (column + 1) * spacingRight / spanCount; // (column + 1) * ((1f / spanCount) * spacing)
if (position < spanCount) { // top edge
outRect.top = spacingTop;
}
outRect.bottom = spacingBottom; // item bottom
} else {
outRect.left = column * spacingLeft / spanCount; // column * ((1f / spanCount) * spacing)
outRect.right = spacingRight - (column + 1) * spacingRight / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)
if (position >= spanCount) {
outRect.top = spacingTop; // item top
}
}
}
}
public class GridAdapter extends RecyclerView.Adapter<GridAdapter.ViewHolder> {
private ArrayList<Model> model;
public GridAdapter(ArrayList<Model> offer) {
super();
model = offer;
}
@Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_item, parent, false);
final ViewHolder holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
final Model currentOffer = model.get(position);
holder.category.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@SuppressLint("NewApi")
@SuppressWarnings("deprecation")
@Override
public void onGlobalLayout() {
int width = holder.category.getWidth();
ViewGroup.LayoutParams params = holder.appIcon.getLayoutParams();
params.width = width;
params.height = width;
holder.appIcon.setLayoutParams(params);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN)
holder.itemView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
else
holder.itemView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
});
Picasso.with(getActivity().getApplicationContext()).
load(currentOffer.getApp_logo()).fit().centerCrop().into(holder.appIcon);
holder.appName.setText(currentOffer.getApp_name());
holder.category.setText(currentOffer.getApp_category());
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String marketURL = AndroidTools.getPlayStoreURL(currentOffer.getApp_store_id(), true);
UITools.launchUrl(getActivity(), marketURL);
}
});
}
@Override
public int getItemCount() {
return model.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
private ImageView appIcon;
private TextView appName;
private TextView category;
public ViewHolder(View itemView) {
super(itemView);
appIcon = (ImageView)itemView.findViewById(R.id.item_icon);
appName = (TextView)itemView.findViewById(R.id.item_app_name);
category = (TextView)itemView.findViewById(R.id.item_category);
}
}
}
}
Любая помощь очень ценится.