使用 NavController 从片段导航到另一个片段

Question

我正在尝试应用我在导航抽屉 Activity 中看到的关于带片段和 MVVM“新组件”的课程，在这个简单的应用程序中，我有三个片段，我尝试使用它们在它们之间导航 navController.addOnDestinationChangedListener 并显示祝酒词，但似乎代码不起作用，我不知道原因

这是我的代码

public class MainActivity extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        FloatingActionButton fab = findViewById(R.id.fab);

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = 
        fragmentManager.beginTransaction();

        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);
        // Passing each menu ID as a set of Ids because each
        // menu should be considered as top level destinations.
        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
                .setDrawerLayout(drawer)
                .build();
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);

        navController.addOnDestinationChangedListener(new NavController.OnDestinationChangedListener() {
            @Override
            public void onDestinationChanged(@NonNull NavController controller, @NonNull NavDestination destination, @Nullable Bundle arguments) {

                int menuId = destination.getId();
                switch (menuId){
                    case R.id.nav_gallery:
                        fab.hide();
                        Toast.makeText(getApplicationContext(),"Gallery",Toast.LENGTH_LONG).show();
                        fragmentTransaction.replace(R.id.homeFragment,new GalleryFragment());
                        fragmentTransaction.addToBackStack(null);
                        fragmentTransaction.commit();

                        NavGraph navGraph = new NavGraph()

//                        controller.getGraph().clear();
//                        controller.navigate(R.id.nav_gallery);


                        break;
                    case R.id.nav_slideshow:
                        fab.hide();
                        Toast.makeText(getApplicationContext(),"Slideshow",Toast.LENGTH_LONG).show();
                        break;


                }

            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
        return NavigationUI.navigateUp(navController, mAppBarConfiguration)
                || super.onSupportNavigateUp();
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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_main"
        app:menu="@menu/activity_main_drawer" />

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</androidx.drawerlayout.widget.DrawerLayout>

content.main.xml

<?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:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_main">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>

mobile_navigation.xml

<?xml version="1.0" encoding="utf-8"?>
<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.test.dummyappv3.ui.home.HomeFragment"
        android:label="@string/menu_home"
        tools:layout="@layout/fragment_home" />

    <fragment
        android:id="@+id/nav_gallery"
        android:name="com.test.dummyappv3.ui.gallery.GalleryFragment"
        android:label="@string/menu_gallery"
        tools:layout="@layout/fragment_gallery" />

    <fragment
        android:id="@+id/nav_slideshow"
        android:name="com.test.dummyappv3.ui.slideshow.SlideshowFragment"
        android:label="@string/menu_slideshow"
        tools:layout="@layout/fragment_slideshow" />
</navigation>

在寻找解决方案时，我发现了这个 answer，并且我尝试像这样使用控制器

controller.getGraph().clear();
controller.navigate(R.id.nav_gallery);

而不是使用片段事务，但它也不起作用

Answer 1

好的，你需要了解两件事。

NavigationController 与 FragmentManager 没有任何共同点，除了它也可以交换片段。
应用您的课程，您需要决定使用 FragmentManager 还是 NavigationController。

同时使用两者不仅会使您自己感到困惑，而且可能会使应用程序本身崩溃。

Answer 2

问题在这里

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

将此包含从此处移动到 NavigationView 的顶部

<?xml version="1.0" encoding="utf-8"?>
<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">

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

    <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_main"
        app:menu="@menu/activity_main_drawer" />



</androidx.drawerlayout.widget.DrawerLayout>

那一切都会好起来的

使用 NavController 从片段导航到另一个片段

Navigate from fragment to another using NavController

android

android-fragments

navigation-drawer

androidx

android-navigationview