Android Fragments 使用导航活动在Recyclerview中膨胀类片段时出错

hmtdttj4  于 2022-11-24  发布在  Android
关注(0)|答案(1)|浏览(181)

我正在制作一个使用Android Studio来编写和调用消息的应用程序。在将回收器视图膨胀到片段中的过程中出现了此错误消息。
我怎么能修好它？为什么这个不能充气？
以下是错误消息...

  1. java.lang.RuntimeException: Unable to start activity ComponentInfo{kr.hnu.project/kr.hnu.project.NavigationActivity}: android.view.InflateException: Binary XML file line #11 in kr.hnu.project:layout/activity_navigation: Binary XML file line #10 in kr.hnu.project:layout/content_navigation: Error inflating class fragment
  2.         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
  3.         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
  4.         at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
  5.         at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
  6.         at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
  7.         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
  8.         at android.os.Handler.dispatchMessage(Handler.java:107)
  9.         at android.os.Looper.loop(Looper.java:214)
  10.         at android.app.ActivityThread.main(ActivityThread.java:7356)
  11.         at java.lang.reflect.Method.invoke(Native Method)
  12.         at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
  13.         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
  14.      Caused by: android.view.InflateException: Binary XML file line #11 in kr.hnu.project:layout/activity_navigation: Binary XML file line #10 in kr.hnu.project:layout/content_navigation: Error inflating class fragment
  15.      Caused by: android.view.InflateException: Binary XML file line #10 in kr.hnu.project:layout/content_navigation: Error inflating class fragment
  16.      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void kr.hnu.project.MyRecyclerAdapter.notifyDataSetChanged()' on a null object reference
  17.         at kr.hnu.project.ui.home.HomeFragment.setArray(HomeFragment.java:83)
  18.         at kr.hnu.project.ui.home.HomeFragment.onCreateView(HomeFragment.java:52)
  19.         at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2995)
  20.         at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:523)
  21.         at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:261)
  22.         at androidx.fragment.app.FragmentStore.moveToExpectedState(FragmentStore.java:113)

以及回收器视图应该看到的HomeFragment。

  1. public class HomeFragment extends Fragment {
  2. private final static String selectMsg = "SELECT sender, receiver, title, date, content FROM MessageDB";
  3. RelativeLayout rel;
  4. LinearLayout lin;
  5. DBHelper dbHelper;
  6. SQLiteDatabase readDB;
  7. Cursor cursor;
  8. ArrayList<MyItem> mailItem;
  9. MyRecyclerAdapter myAdapter;
  11. private FragmentHomeBinding binding;
  13. public View onCreateView(@NonNull LayoutInflater inflater,
  14.                          ViewGroup container, Bundle savedInstanceState) {
  15.     HomeViewModel homeViewModel =
  16.             new ViewModelProvider(this).get(HomeViewModel.class);
  18.     binding = FragmentHomeBinding.inflate(inflater, container, false);
  19.     View root = binding.getRoot();
  20.     ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_home, container, false);
  22.     dbHelper = new DBHelper(inflater.getContext());
  23.     readDB = dbHelper.getReadableDatabase();
  24.     mailItem = new ArrayList<MyItem>();
  26.     setArray();
  28.     myAdapter = new MyRecyclerAdapter(getActivity(), mailItem);
  29.     RecyclerView recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview);
  30.     recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
  31.     recyclerView.setAdapter(myAdapter);
  35.     return root;
  36. }
  38. public void setArray() {
  39.     cursor = readDB.rawQuery(selectMsg, null);
  40.     mailItem.clear();
  42.     while (cursor.moveToNext()) {
  44.         mailItem.add(new MyItem(cursor.getString(cursor.getColumnIndexOrThrow("sender")), cursor.getString(cursor.getColumnIndexOrThrow("receiver")),
  45.                 cursor.getString(cursor.getColumnIndexOrThrow("title")), cursor.getString(cursor.getColumnIndexOrThrow("date")),
  46.                 cursor.getString(cursor.getColumnIndexOrThrow("content"))));
  48.     }
  50.     cursor.close();
  51.    //myAdapter.notifyDataSetChanged();
  53. }

这是具有home片段导航活动

  1. public class NavigationActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
  3. private AppBarConfiguration mAppBarConfiguration;
  4. private ActivityNavigationBinding binding;
  6. @Override
  7. protected void onCreate(Bundle savedInstanceState) {
  8.     super.onCreate(savedInstanceState);
  10.     dataToFragment(); 
  12.     binding = ActivityNavigationBinding.inflate(getLayoutInflater());
  13.     setContentView(binding.getRoot());
  15.     setSupportActionBar(binding.appBarNavigation.toolbar); 
  17.     DrawerLayout drawer = binding.drawerLayout;
  18.     NavigationView navigationView = binding.navView;
  19.     navigationView = findViewById(R.id.nav_view);
  20.     navigationView.setNavigationItemSelectedListener(this); 
  22.     //
  23.     mAppBarConfiguration = new AppBarConfiguration.Builder( 
  24.             R.id.nav_send, R.id.nav_set, R.id.nav_home)
  25.             .setOpenableLayout(drawer)
  26.             .build();
  27.     NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_navigation);
  28.     NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
  29.     NavigationUI.setupWithNavController(navigationView, navController);
  30. }

这是错误消息中的activity_navigation. xml

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <androidx.drawerlayout.widget.DrawerLayout 
  3. xmlns:android="http://schemas.android.com/apk/res/android"
  4. xmlns:app="http://schemas.android.com/apk/res-auto"
  5. xmlns:tools="http://schemas.android.com/tools"
  6. android:id="@+id/drawer_layout"
  7. android:layout_width="match_parent"
  8. android:layout_height="match_parent"
  9. android:fitsSystemWindows="true"
  10. tools:openDrawer="start">
  12. <include
  13.     android:id="@+id/app_bar_navigation"
  14.     layout="@layout/app_bar_navigation"
  15.     android:layout_width="match_parent"
  16.     android:layout_height="match_parent" />
  19. <com.google.android.material.navigation.NavigationView
  20.     android:id="@+id/nav_view"
  21.     android:layout_width="wrap_content"
  22.     android:layout_height="match_parent"
  23.     android:layout_gravity="start"
  24.     android:fitsSystemWindows="true"
  25.     app:headerLayout="@layout/nav_header_navigation"
  26.     app:menu="@menu/activity_navigation_drawer" />
  27. </androidx.drawerlayout.widget.DrawerLayout>

这是错误消息中的内容_导航. xml

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <androidx.constraintlayout.widget.ConstraintLayout 
  3. xmlns:android="http://schemas.android.com/apk/res/android"
  4. xmlns:app="http://schemas.android.com/apk/res-auto"
  5. xmlns:tools="http://schemas.android.com/tools"
  6. android:layout_width="match_parent"
  7. android:layout_height="match_parent"
  8. app:layout_behavior="@string/appbar_scrolling_view_behavior"
  9. tools:showIn="@layout/app_bar_navigation">
  11. <fragment
  12.     android:id="@+id/nav_host_fragment_content_navigation"
  13.     android:name="androidx.navigation.fragment.NavHostFragment"
  14.     android:layout_width="match_parent"
  15.     android:layout_height="match_parent"
  16.     app:defaultNavHost="true"
  17.     app:layout_constraintHorizontal_bias="0.0"
  18.     app:layout_constraintLeft_toLeftOf="parent"
  19.     app:layout_constraintRight_toRightOf="parent"
  20.     app:layout_constraintTop_toTopOf="parent"
  21.     app:navGraph="@navigation/mobile_navigation" /

</androidx.constraintlayout.widget.ConstraintLayout>
这是homeFragment的xml文件

  1. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  2. xmlns:tools="http://schemas.android.com/tools"
  3. android:id="@+id/linear"
  4. android:layout_width="match_parent"
  5. android:layout_height="match_parent"
  6. android:orientation="vertical"
  7. tools:context=".ui.home.HomeFragment">
  9. <androidx.recyclerview.widget.RecyclerView
  10.     android:id="@+id/recyclerview"
  11.     android:layout_width="match_parent"
  12.     android:layout_height="match_parent"/>
  13. </LinearLayout>
android-fragments

1条答案

按热度按时间
bvjxkvbb

bvjxkvbb1#

因为我的声望低于50，我不能评论你的帖子，所以我会在这里评论。
这个方法有什么作用？dataToFragment();在扩大布局之前调用它

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