Ошибка: попытка вызвать метод интерфейса int java .util.List.size () для пустой ссылки на объект - PullRequest
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Ошибка: попытка вызвать метод интерфейса int java .util.List.size () для пустой ссылки на объект

0 голосов
/ 27 марта 2020

Я хочу получить доступ к некоторым действиям из моего библиотечного модуля (общий). Когда я нажимаю на потрясающую кнопку в ClassActivity (которая из другого модуля: teacher), она работает нормально, она отправляет меня в AddClassActivity

Но когда я нажимаю «Сохранить» (чтобы отобразить RecyclelerView в ClassActivity), ничего не отображается, и я получаю эту ошибку: 

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.schoolteacher, PID: 26602
    java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
        at com.example.common.Adapter.NotesAdapter.getItemCount(NotesAdapter.java:56)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:4044)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3849)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at androidx.coordinatorlayout.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1213)
        at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:899)
        at com.google.android.material.appbar.ViewOffsetBehavior.layoutChild(ViewOffsetBehavior.java:66)
        at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:152)
        at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:43)
        at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1892)
        at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:918)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:325)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1842)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1686)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1595)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:325)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1842)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1686)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1595)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:325)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at com.android.internal.policy.DecorView.onLayout(DecorView.java:926)
        at android.view.View.layout(View.java:20960)
        at android.view.ViewGroup.layout(ViewGroup.java:6279)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3037)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2545)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1636)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7946)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1092)
        at android.view.Choreographer.doCallbacks(Choreographer.java:893)
        at android.view.Choreographer.doFrame(Choreographer.java:812)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1078)
        at android.os.Handler.handleCallback(Handler.java:907)
        at android.os.Handler.dispatchMessage(Handler.java:105)
        at android.os.Looper.loop(Looper.java:216)
        at android.app.ActivityThread.main(ActivityThread.java:7625)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)

Вот мой ClassActivity из «модуля учителя»: 

public class ClassActivity extends AppCompatActivity {

    // Firebase instance variables
    private FirebaseAuth mFirebaseAuth;
    private FirebaseUser mFirebaseUser;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_class);


        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        View decorView = getWindow().getDecorView();
        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);

        BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
        bottomNav.setSelectedItemId(R.id.bottomBarItemSecond);


        bottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                switch (item.getItemId()) {
                    case R.id.bottomBarItemFirst:
                        startActivity(new Intent(getApplicationContext(), MainActivity.class));
                        overridePendingTransition(0,0);
                        break;
                    case R.id.bottomBarItemSecond:

                        break;
                    case R.id.bottomBarItemThird:
                        startActivity(new Intent(getApplicationContext(), MessageActivity.class));
                        overridePendingTransition(0,0);
                        break;
                    case R.id.bottomBarItemFourth:
                        break;
                    case R.id.bottomBarItemFifth:
                        break;
                }

                return true;
            }
        });



        // Initialize Firebase Auth
        mFirebaseAuth = FirebaseAuth.getInstance();
        mFirebaseUser = mFirebaseAuth.getCurrentUser();


    }



    public void fabClick(View v){
        Intent intent = new Intent(ClassActivity.this, com.example.common.AddClassActivity.class);
        ClassActivity.this.startActivity(intent);
    }

    @Override
    public void onStart() {
        super.onStart();
        FirebaseUser currentUser = mFirebaseAuth.getCurrentUser();
        if(currentUser == null){
            sendToStart();
        }
    }

    private void sendToStart() {
        Intent startIntent = new Intent(ClassActivity.this, LoginActivity.class);
        startActivity(startIntent);
        finish();
    }

}

Вот AndroidManifest из библиотечного модуля (общий) 

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.common">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application>
        <activity android:name=".AddAssignmentActivity"></activity>
        <activity
            android:name=".AddClassActivity"
            android:label="Create Class">
            <intent-filter>
                <action android:name="com.example.schoolteacher.ClassActivity" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>

        <activity android:name=".HomeScreen"
            android:label="Classes">
        </activity>

        <activity android:name=".EditActivity"
            android:label="Edit Class"
            android:parentActivityName=".HomeScreen">

        </activity>


    </application>

</manifest>

Вот мой общий библиотечный репозиторий: Общая библиотека

Пожалуйста, мне нужна помощь в этом вопросе !

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