ConstraintLayout没有为在RecyclerView上单击的项目设置NavController [英] ConstraintLayout does not have a NavController set for item clicked on RecyclerView
本文介绍了ConstraintLayout没有为在RecyclerView上单击的项目设置NavController的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
当我单击某个项目时，它有时会起作用，有时会崩溃.
When I click on an item, sometimes it works and sometimes it crashes.
下面是单击某个项目后的致命异常.
Below is the FATAL EXCEPTION after clicking on an item.
2020-03-31 21:59:18.087 15383-15383/com.aliton.myapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.aliton.myapp, PID: 15383
java.lang.IllegalStateException: View androidx.constraintlayout.widget.ConstraintLayout{b3bb13b V.E...C.. .......D 0,336-720,518} does not have a NavController set
at androidx.navigation.Navigation.findNavController(Navigation.java:84)
at com.aliton.myapp.Adapter.StoreSelectAdapter$StoreSelectViewHolder$1.onChanged(StoreSelectAdapter.java:147)
at com.aliton.myapp.Adapter.StoreSelectAdapter$StoreSelectViewHolder$1.onChanged(StoreSelectAdapter.java:142)
at androidx.lifecycle.LiveData.considerNotify(LiveData.java:131)
at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:149)
at androidx.lifecycle.LiveData.setValue(LiveData.java:307)
at androidx.lifecycle.MutableLiveData.setValue(MutableLiveData.java:50)
at androidx.lifecycle.LiveData$1.run(LiveData.java:91)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6351)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:896)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:786)
在这种情况下，首先我需要将一个项目(StoreEntity)插入我的房间数据库中，侦听其id，然后导航到具有direction中定义的对象的其他片段.
In this case, first I need to insert an item (StoreEntity) into my room database, listen to its id and then navigate to other fragment with objects defined in direction.
下面是我的适配器:
public class StoreSelectAdapter extends RecyclerView.Adapter<StoreSelectAdapter.StoreSelectViewHolder> {
private static final String TAG = "debinf SummaryAdapter";
private FragmentActivity fragmentActivity;
public StoreSelectAdapter(FragmentActivity fragmentActivity) {
this.fragmentActivity = fragmentActivity;
}
private static final DiffUtil.ItemCallback<StoreModel> DIFF_CALLBACK = new DiffUtil.ItemCallback<StoreModel>() {
@Override
public boolean areItemsTheSame(@NonNull StoreModel oldItem, @NonNull StoreModel newItem) {
return oldItem.getKey().equals(newItem.getKey());
}
@Override
public boolean areContentsTheSame(@NonNull StoreModel oldItem, @NonNull StoreModel newItem) {
return oldItem.getKey().equals(newItem.getKey()) && oldItem.getName().equals(newItem.getName()) && oldItem.getAddress().equals(newItem.getAddress());
}
};
private AsyncListDiffer<StoreModel> differ = new AsyncListDiffer<StoreModel>(this, DIFF_CALLBACK);
@NonNull
@Override
public StoreSelectViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_select_store, parent, false);
return new StoreSelectViewHolder(view, fragmentActivity);
}
@Override
public void onBindViewHolder(@NonNull StoreSelectViewHolder holder, int position) {
StoreModel store = differ.getCurrentList().get(position);
Log.i(TAG, "onBindViewHolder: "+store.getName());
holder.storeName.setText(store.getName());
holder.storeAddress.setText(store.getAddress());
if (store.getImage() != null && !store.getImage().isEmpty()) {
Picasso.get().load(store.getImage()).networkPolicy(NetworkPolicy.OFFLINE).into(holder.storeImage, new Callback() {
@Override
public void onSuccess() {
}
@Override
public void onError(Exception e) {
Picasso.get().load(store.getImage()).into(holder.storeImage);
}
});
} else {
holder.storeImage.setImageResource(android.R.drawable.stat_sys_phone_call_on_hold);
}
/*holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.i(TAG, "onClick: onBindViewHolder");
Toast.makeText(context, "onClick: onBindViewHolder", Toast.LENGTH_SHORT).show();
AddstoreFragmentDirections.ActionAddstoreFragmentToBarcodeFragment direction = AddstoreFragmentDirections.actionAddstoreFragmentToBarcodeFragment(store);
Navigation.createNavigateOnClickListener()
}
});*/
}
@Override
public int getItemCount() {
return differ.getCurrentList().size();
}
public void submitList(List<StoreModel> stores) {
differ.submitList(stores);
}
public List<StoreModel> getCurrentItemList() {
return differ.getCurrentList();
}
public class StoreSelectViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
//private static final String TAG = "StoreSelectViewHolder";
public ImageView storeImage;
public TextView storeName, storeAddress;
private FragmentActivity fragmentActivity;
private LocalDatabaseViewModel localDatabaseViewModel;
public StoreSelectViewHolder(@NonNull View itemView, FragmentActivity fragmentActivity) {
super(itemView);
storeImage = (ImageView) itemView.findViewById(R.id.item_store_image);
storeName = (TextView) itemView.findViewById(R.id.item_store_name);
storeAddress = (TextView) itemView.findViewById(R.id.item_store_address);
this.fragmentActivity = fragmentActivity;
itemView.setOnClickListener(this);
}
@Override
public void onClick(View v) {
StoreModel store = differ.getCurrentList().get(getAdapterPosition());
Log.i(TAG, "onClick: storeName selected: "+store.getName());
Log.i(TAG, "onClick: storeKey selected: "+store.getKey());
StoreEntity storeEntity = new StoreEntity(store.getName(), store.getImage());
storeEntity.setKey(store.getKey());
localDatabaseViewModel = ViewModelProviders.of(fragmentActivity).get(LocalDatabaseViewModel.class);
localDatabaseViewModel.getStoreIdFromInsertedItem().observe(fragmentActivity, new Observer<Long>() {
@Override
public void onChanged(Long itemId) {
Log.i(TAG, "onChanged: itemId in adapter is "+itemId);
SelectstoreFragmentDirections.ActionSelectstoreFragmentToBarcodeFragment direction = SelectstoreFragmentDirections.actionSelectstoreFragmentToBarcodeFragment(store, itemId);
Navigation.findNavController(v).navigate(direction); // this is the StoreSelectAdapter.java:147
}
});
localDatabaseViewModel.insertStore(storeEntity);
}
}
}
感谢您为解决此问题所提供的帮助.
I appreciate any help to solve this issue.
编辑
下面是我的activity_main.xml，其中声明了我的片段NavHost.
Below is my activity_main.xml where my fragment NavHost is declared.
<androidx.drawerlayout.widget.DrawerLayout
android:id="@+id/main_drawer"
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=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/main_fragment"
android:layout_width="0dp"
android:layout_height="0dp"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="@id/main_bottomnav"
app:defaultNavHost="true"
app:navGraph="@navigation/mainnav_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/main_bottomnav"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="@menu/main_navmenu"
android:background="@color/colorAccent"
app:itemIconTint="@drawable/botton_item_color"
app:itemTextColor="@drawable/botton_item_color">
</com.google.android.material.bottomnavigation.BottomNavigationView>
</androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/main_sidebar"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:menu="@menu/main_sidebarmenu"/>
</androidx.drawerlayout.widget.DrawerLayout>
下面是我的mainnav_graph.xml
...
<fragment
android:id="@+id/barcodeFragment"
android:name="com.aliton.myapp.BarcodeFragment"
android:label="fragment_barcode"
tools:layout="@layout/fragment_barcode" >
<argument
android:name="store"
app:argType="com.aliton.myapp.Model.StoreModel" />
<action
android:id="@+id/action_barcodeFragment_to_productdetailFragment"
app:destination="@id/productdetailFragment" />
<argument
android:name="storeId"
app:argType="long" />
</fragment>
<fragment
android:id="@+id/selectstoreFragment"
android:name="com.aliton.myapp.SelectstoreFragment"
android:label="fragment_selectstore"
tools:layout="@layout/fragment_selectstore" >
<action
android:id="@+id/action_selectstoreFragment_to_addstoreFragment"
app:destination="@id/addstoreFragment" />
<action
android:id="@+id/action_selectstoreFragment_to_barcodeFragment"
app:destination="@id/barcodeFragment" />
</fragment>
...
下面是我的fragment_selectstore.xml作为SelectstoreFragment.java的内容.
And below is my fragment_selectstore.xml as the content of SelectstoreFragment.java.
<androidx.constraintlayout.widget.ConstraintLayout
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=".SelectstoreFragment">
<androidx.cardview.widget.CardView
android:id="@+id/selectstore_cardview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
app:cardCornerRadius="10dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<TextView
android:id="@+id/selectstore_question"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Are you at any of the store shown below?"
android:textSize="28sp"
android:gravity="center"
android:textStyle="bold"/>
</androidx.cardview.widget.CardView>
<FrameLayout
android:id="@+id/selectstore_framelayout"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginTop="2dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="@+id/selectstore_cardview">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/selectstore_recyclerview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical">
</androidx.recyclerview.widget.RecyclerView>
<TextView
android:id="@+id/selectstore_nodata"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:text="No store found!"
android:textSize="22sp" />
</FrameLayout>
<com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
android:id="@+id/selectstore_fab"
style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="8dp"
android:contentDescription="Outra loja desc"
android:text="Outra loja"
app:icon="@drawable/common_full_open_on_phone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
更新
1)我还实现了interface以便在Adapter和Fragment之间进行通信，以将view放入onViewCreated()中，但是该应用始终崩溃.
1) I've also implemented an interface for communication between Adapter and Fragment to get the view in the onViewCreated(), but the app keeps crashing.
2)我还尝试使用以下命令获取在片段布局中定义的NavHostFragment的navController
2) I've also tried to get the navController of my NavHostFragment defined in the fragment layout, using the following command
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Log.i(TAG, "onViewCreated: ");
// https://stackoverflow.com/a/53902696/4300670
// NOT WORKING
adapter = new StoreSelectAdapter(getActivity(), new StoreSelectAdapter.OnStoreSelectListener() {
@Override
public void onStoreSelected(StoreModel storeModel, Long itemId) {
SelectstoreFragmentDirections.ActionSelectstoreFragmentToBarcodeFragment direction = SelectstoreFragmentDirections.actionSelectstoreFragmentToBarcodeFragment(storeModel, itemId);
Navigation.findNavController(getActivity(), R.id.main_fragment).navigate(direction);
}
});
storeRecyclerview.setAdapter(adapter);
}
但是现在我得到了 NullPointerException
2020-04-02 17:11:22.163 6015-6015/com.aliton.myapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.aliton.myapp, PID: 6015
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Activity.requireViewById(int)' on a null object reference
at androidx.core.app.ActivityCompat.requireViewById(ActivityCompat.java:363)
at androidx.navigation.Navigation.findNavController(Navigation.java:58)
at com.aliton.myapp.SelectstoreFragment$4.onStoreSelected(SelectstoreFragment.java:221)
at com.aliton.myapp.Adapter.StoreSelectAdapter$StoreSelectViewHolder$1.onChanged(StoreSelectAdapter.java:149)
at com.aliton.myapp.Adapter.StoreSelectAdapter$StoreSelectViewHolder$1.onChanged(StoreSelectAdapter.java:145)
at androidx.lifecycle.LiveData.considerNotify(LiveData.java:131)
at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:149)
at androidx.lifecycle.LiveData.setValue(LiveData.java:307)
at androidx.lifecycle.MutableLiveData.setValue(MutableLiveData.java:50)
at androidx.lifecycle.LiveData$1.run(LiveData.java:91)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
3)我已经复制了Navigation类中的方法，以便了解导致错误的原因，并且它们是:
3) I've copied the methods inside Navigation class in order to understand what is causing the error and here they are:
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Log.i(TAG, "onViewCreated: ");
adapter = new StoreSelectAdapter(getActivity(), new StoreSelectAdapter.OnStoreSelectListener() {
@Override
public void onStoreSelected(StoreModel storeModel, Long itemId) {
SelectstoreFragmentDirections.ActionSelectstoreFragmentToBarcodeFragment direction = SelectstoreFragmentDirections.actionSelectstoreFragmentToBarcodeFragment(storeModel, itemId);
NavController navController = myFindViewNavController(view);
if (navController == null) {
Log.i(TAG, "onStoreSelected: ISSUE NavController set");
}
}
});
storeRecyclerview.setAdapter(adapter);
}
private NavController myFindViewNavController(View view) {
while (view != null) {
Log.i(TAG, "myFindViewNavController: view != null - "+view);
NavController controller = myGetViewNavController(view);
if (controller != null) {
Log.i(TAG, "myFindViewNavController: controller != null");
return controller;
}
ViewParent parent = view.getParent();
view = parent instanceof View ? (View) parent : null;
Log.i(TAG, "myFindViewNavController: view.getParent() - "+view);
}
return null;
}
private NavController myGetViewNavController(View view) {
Object tag = view.getTag(R.id.nav_controller_view_tag);
Log.i(TAG, "myGetViewNavController: tag is "+tag);
NavController controller = null;
if (tag instanceof WeakReference) {
Log.i(TAG, "myGetViewNavController: tag instanceof WeakReference");
controller = ((WeakReference<NavController>) tag).get();
} else if (tag instanceof NavController) {
Log.i(TAG, "myGetViewNavController: tag instanceof NavController");
controller = (NavController) tag;
}
return controller;
}
验证日志猫，看来我的adapter中的ViewModel在导航到下一个片段后再次被触发:
Verifying the logcat, it seems that the ViewModel in my adapter is been triggered once again after navigating to the next fragment:
debinf SummaryAdapter: onClick: storeName selected: Posto Shell Convem
debinf SummaryAdapter: onClick: storeKey selected: M0Ysk5jRIdtiJ9zyUhXG
debinf SummaryAdapter: onChanged: itemId in adapter is 40, view id: -1
debinf SelStoreFrag: myFindViewNavController: view != null - androidx.constraintlayout.widget.ConstraintLayout{fb9835d V.E...... ........ 0,0-1080,1437}
debinf SelStoreFrag: myGetViewNavController: tag is null
debinf SelStoreFrag: myFindViewNavController: view.getParent() - android.widget.FrameLayout{4af5206 V.E...... ........ 0,0-1080,1437 #7f090137 app:id/main_fragment}
debinf SelStoreFrag: myFindViewNavController: view != null - android.widget.FrameLayout{4af5206 V.E...... ........ 0,0-1080,1437 #7f090137 app:id/main_fragment}
debinf SelStoreFrag: myGetViewNavController: tag is androidx.navigation.NavController@47f0c7
debinf SelStoreFrag: myGetViewNavController: tag instanceof NavController
debinf SelStoreFrag: myFindViewNavController: controller != null
debinf BarcodeFrag: onCreateView:
debinf BarcodeFrag: onCreateView: fragArgs is com.aliton.myapp.Model.StoreModel@77fbfcb
debinf BarcodeFrag: onPermissionGranted:
debinf BarcodeFrag: startCamera:
debinf ExtFun: isFlashSupported: false
debinf ExtFun: startCameraForAllDevices:
debinf BarcodeFrag: onResume:
debinf SummaryAdapter: onChanged: itemId in adapter is 41, view id: -1
debinf SelStoreFrag: myFindViewNavController: view != null - androidx.constraintlayout.widget.ConstraintLayout{fb9835d V.E...... .......D 0,0-1080,1437}
debinf SelStoreFrag: myGetViewNavController: tag is null
debinf SelStoreFrag: myFindViewNavController: view.getParent() - null
debinf SelStoreFrag: onStoreSelected: ISSUE NavController set
该解决方案似乎将通过正确解决adapter中通过ViewModel插入的项目id的侦听而来.
It seems that the solution will come by properly solving the listening of the inserted item id via ViewModel in the adapter.
推荐答案
IllegalStateException或NullPointerException不再出现，因为我已经从adapter中删除了ViewModel并将其放在了fragment.
The IllegalStateException or NullPointerException is no longer occurring, since I've removed the ViewModel from the adapter and placed it in the fragment.
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Log.i(TAG, "onViewCreated: ");
localDatabaseViewModel = ViewModelProviders.of(getActivity()).get(LocalDatabaseViewModel.class);
adapter = new StoreSelectAdapter(new StoreSelectAdapter.OnStoreSelectListener() {
@Override
public void onStoreSelected(StoreModel storeModel) {
StoreEntity storeEntity = new StoreEntity(storeModel.getName(), storeModel.getImage());
storeEntity.setKey(storeModel.getKey());
localDatabaseViewModel.getStoreIdFromInsertedItem().observe(getViewLifecycleOwner(), new Observer<Long>() {
@Override
public void onChanged(Long itemId) {
SelectstoreFragmentDirections.ActionSelectstoreFragmentToBarcodeFragment direction = SelectstoreFragmentDirections.actionSelectstoreFragmentToBarcodeFragment(storeModel, itemId);
Navigation.findNavController(view).navigate(direction);
}
});
localDatabaseViewModel.insertStore(storeEntity);
}
});
storeRecyclerview.setAdapter(adapter);
}
并停止收听会议室数据库中插入项目的id.
And stop listening to the id of the inserted item in the room database.
@Override
public void onStop() {
Log.i(TAG, "onStop: ");
if (localDatabaseViewModel != null) {
localDatabaseViewModel.getStoreIdFromInsertedItem().removeObservers(getViewLifecycleOwner());
}
super.onStop();
}
这篇关于ConstraintLayout没有为在RecyclerView上单击的项目设置NavController的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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