java.lang.IllegalStateException : does not have a NavController set on xxxxx(location address) error 错误

Question

我在 Android 中创建一个用户主页 Activity ，当我的应用程序在登录后尝试访问 UserHome Activity 时，我的应用程序崩溃了。我无法弄清楚为什么会这样。

错误java.lang.IllegalStateException: Activity com.example.commerce.UserHome@xxxxxxx 没有在 XXXXXXXXXXX 上设置 NavController

**(X,x表示一些字母数字地址)

activity_user_home.xml

<androidx.drawerlayout.widget.DrawerLayout 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:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_user_home"
        app:menu="@menu/activity_user_home_drawer" />

    <include
        layout="@layout/app_bar_user_home"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.drawerlayout.widget.DrawerLayout>

mobile_navigation.xml

<navigation 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:id="@+id/mobile_navigation"
    app:startDestination="@+id/nav_home"
    >

    <fragment
        android:id="@+id/nav_home"
        android:name="com.example.commerce.ui.home.HomeFragment"
        android:label="@string/menu_home"
        tools:layout="@layout/fragment_home">

        <action
            android:id="@+id/action_HomeFragment_to_HomeSecondFragment"
            app:destination="@id/nav_home_second" />
    </fragment>
    <fragment
        android:id="@+id/nav_home_second"
        android:name="com.example.commerce.ui.home.HomeSecondFragment"
        android:label="@string/home_second"
        tools:layout="@layout/fragment_home_second">
        <action
            android:id="@+id/action_HomeSecondFragment_to_HomeFragment"
            app:destination="@id/nav_home" />

        <argument
            android:name="myArg"
            app:argType="string" />
    </fragment>

    <fragment
        android:id="@+id/nav_gallery"
        android:name="com.example.commerce.ui.gallery.GalleryFragment"
        android:label="@string/menu_gallery"
        tools:layout="@layout/fragment_gallery" />

    <fragment
        android:id="@+id/nav_slideshow"
        android:name="com.example.commerce.ui.slideshow.SlideshowFragment"
        android:label="@string/menu_slideshow"
        tools:layout="@layout/fragment_slideshow" />
</navigation>

我的 UserHome 类中的 OnCreate 方法

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_user_home);

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

        toolbar.setTitle("Home");


        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);

        navigationView.bringToFront();    

        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
                .setDrawerLayout(drawer)
                .build();

        NavController navController = Navigation.findNavController(UserHome.this, R.id.nav_view);

        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);
    }

谁能解释一下是什么原因造成的。

Answer 1

你错过了这样定义你的 navHostFragment:

<fragment
       android:layout_width="match_parent"
       android:layout_height="match_parent"
        android:name="androidx.navigation.fragment.NavHostFragment"
       android:id="@+id/nav_host_fragment"
       app:navGraph="@navigation/mobile_navigation" />

这个 fragment 是所有由 navController 管理的目的地 fragment 的宿主，navController 将每个 id(通过菜单)链接到它在 navGraph 中的目的地希望这能帮助您解决问题；