NullPointerException：尝试在空对象引用上调用虚拟方法“int android.view.ViewGroup.getPaddingBottom()”

Question

当我尝试将菜单膨胀到

BottomNavigationView

时崩溃，但同样崩溃了。我已将材料设计库从

'com.google.android.material:material:1.2.1'

更新为

'com.google.android.material:material:1.6.1'

。

注意：使用相同的代码

不会崩溃

'com.google.android.material:material:1.2.1'

MainActivity

public class MainActivity extends AppCompatActivity {
    private final BottomNavigationView.OnNavigationItemSelectedListener bottomNavListener = item -> {
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bottomNavigationView = findViewById(R.id.bottom_navigation);
        bottomNavigationView.setItemIconTintList(null);
        bottomNavigationView.setOnNavigationItemSelectedListener(bottomNavListener);
        bottomNavigationView.getMenu().clear();
        bottomNavigationView.inflateMenu(R.menu.menu_bottom_navigation); // CRASH IS HERE
    }
}

menu_bottom_navigation

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

    <item
        android:id="@+id/bottom_nav_home"
        android:icon="@drawable/bottom_nav_home_icon_selector"
        android:title="@string/home_title" />

    <item
        android:id="@+id/bottom_nav_screen2"
        android:icon="@drawable/bottom_nav_screen2_icon_selector"
        android:title="@string/savings_screen2" />

    <item
        android:id="@+id/bottom_nav_screen3"
        android:icon="@drawable/bottom_nav_screen3_icon_selector"
        android:title="@string/screen3_title" />

    <item
        android:id="@+id/bottom_nav_screen4"
        android:icon="@drawable/bottom_nav_screen4_icon_selector"
        android:title="@string/screen4_title" />

    <item
        android:id="@+id/bottom_nav_screen5"
        android:icon="@drawable/bottom_nav_screen5_icon_selector"
        android:title="@string/screen5_title" />

</menu>

activity_main

<?xml version="1.0" encoding="utf-8"?>
<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:id="@+id/layout"
    android:layout_height="match_parent"
    tools:context=".ui.main.MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/main_fragment_container"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:itemTextAppearanceActive="@style/BottomNavigationView.Active"
        app:itemTextAppearanceInactive="@style/BottomNavigationView"
        app:itemTextColor="@drawable/bottom_nav_selector"
        app:labelVisibilityMode="labeled"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/main_fragment_container" />

</androidx.constraintlayout.widget.ConstraintLayout>

Error

2022-06-14 19:49:18.562 18439-18439/com.example.android.debug E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android.debug, PID: 18439
    java.lang.RuntimeException: Unable to start activity 
    ComponentInfo{com.example.android.debug/com.example.android.ui.main.MainActivity}: 
    java.lang.NullPointerException: Attempt to invoke virtual method 'int 
    android.view.ViewGroup.getPaddingBottom()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

通过创建

design_bottom_navigation_item.xml

的副本并将其放入

res/layout

来解决此问题

https://github.com/material-components/material-components-android/issues/2064#issuecomment-2057269767