我的主要活动中有一个片段容器视图，我想在单击后退按钮时浏览片段

Question

override fun onBackPressed() {

        findNavController(R.id.fragmentContainerView2).popBackStack()
    }

这是我用于背包导航的代码，但该应用程序不会在HOME片段上退出，如果我按第一个片段上的Back Back按钮，则该应用程序应关闭。如何做？

这是我的mainActivity.xml文件，

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.motion.widget.MotionLayout 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/motion_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutDescription="@xml/activity_main_scene2">


    <ImageView
        android:id="@+id/imageView7"
        android:layout_width="60dp"
        android:layout_height="50dp"
        android:contentDescription="@string/logo"
        android:src="@drawable/notification_icon"
        app:layout_constraintBottom_toBottomOf="@+id/imageView8"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="@+id/imageView8" />

    <ImageView
        android:id="@+id/image8"
        android:layout_width="75dp"
        android:layout_height="75dp"
        android:layout_marginStart="15dp"
        android:background="@color/white"
        android:contentDescription="@string/navigation_drawer"
        android:src="@drawable/three_lines"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/thehelfen"
        android:textColor="@color/black"
        android:textSize="20sp"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.fragment.app.FragmentContainerView
            android:id="@+id/fragmentContainerView2"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="55dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/navigation2" />

    <androidx.cardview.widget.CardView
        android:id="@+id/cardView"
        android:layout_width="300dp"
        android:layout_height="match_parent"
        app:cardBackgroundColor="@color/white"
        app:cardElevation="150dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <ImageView
                android:id="@+id/logo"
                android:layout_width="match_parent"
                android:layout_height="150dp"
                android:clickable="true"
                android:contentDescription="@string/logo"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/person"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

            <TextView
                android:id="@+id/my_profile"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/my_profile"
                android:textColor="@color/black"
                android:textSize="35sp"
                android:textStyle="bold"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/logo" />

            <ImageView
                android:id="@+id/icon1"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/consultnow"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/my_profile" />

            <TextView
                android:id="@+id/consultnow"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20dp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/consult_now"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon1"
                app:layout_constraintStart_toEndOf="@+id/icon1"
                app:layout_constraintTop_toTopOf="@+id/icon1" />

            <ImageView
                android:id="@+id/icon2"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/booklabtest"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/icon1" />

            <TextView
                android:id="@+id/booklabtest"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/book_lab_test"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon2"
                app:layout_constraintStart_toEndOf="@+id/icon2"
                app:layout_constraintTop_toTopOf="@+id/icon2" />

            <ImageView
                android:id="@+id/icon3"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/bookhealthpackage"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/icon2" />

            <TextView
                android:id="@+id/bookhealth"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/book_health_npackages"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon3"
                app:layout_constraintStart_toEndOf="@+id/icon3"
                app:layout_constraintTop_toTopOf="@+id/icon3" />

            <ImageView
                android:id="@+id/icon4"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/info_icon"
                app:layout_constraintBottom_toTopOf="@+id/contact_icon"
                app:layout_constraintStart_toStartOf="parent" />

            <TextView
                android:id="@+id/about"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/about_us"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon4"
                app:layout_constraintStart_toEndOf="@+id/icon4"
                app:layout_constraintTop_toTopOf="@+id/icon4" />

            <ImageView
                android:id="@+id/contact_icon"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/contact_us"
                app:layout_constraintBottom_toTopOf="@+id/icon5"
                app:layout_constraintStart_toStartOf="parent" />

            <TextView
                android:id="@+id/contact_us"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/contact_us"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/contact_icon"
                app:layout_constraintStart_toEndOf="@+id/contact_icon"
                app:layout_constraintTop_toTopOf="@+id/contact_icon" />

            <ImageView
                android:id="@+id/icon5"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/faq"
                app:layout_constraintBottom_toTopOf="@+id/icon6"
                app:layout_constraintStart_toStartOf="parent" />

            <TextView
                android:id="@+id/faq"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/faqs"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon5"
                app:layout_constraintStart_toEndOf="@+id/icon5"
                app:layout_constraintTop_toTopOf="@+id/icon5" />

            <ImageView
                android:id="@+id/icon6"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/tandc"
                app:layout_constraintBottom_toTopOf="@+id/icon7"
                app:layout_constraintStart_toStartOf="parent" />

            <TextView
                android:id="@+id/termsandconditions"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/terms_and_conditions"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon6"
                app:layout_constraintStart_toEndOf="@+id/icon6"
                app:layout_constraintTop_toTopOf="@+id/icon6" />

            <ImageView
                android:id="@+id/icon7"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_margin="25dp"
                android:clickable="true"
                android:contentDescription="@string/icon"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:src="@drawable/log_out"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent" />

            <TextView
                android:id="@+id/log_out"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20sp"
                android:clickable="true"
                android:focusable="true"
                android:foreground="?attr/selectableItemBackgroundBorderless"
                android:text="@string/log_out"
                android:textColor="@color/black"
                android:textSize="20sp"
                app:layout_constraintBottom_toBottomOf="@+id/icon7"
                app:layout_constraintStart_toEndOf="@+id/icon7"
                app:layout_constraintTop_toTopOf="@+id/icon7" />


        </androidx.constraintlayout.widget.ConstraintLayout>


    </androidx.cardview.widget.CardView>


</androidx.constraintlayout.motion.widget.MotionLayout>

这是我的Motionscene文件，

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

    <Transition
        motion:constraintSetEnd="@+id/end"
        motion:constraintSetStart="@id/start"
        motion:duration="500">
       <KeyFrameSet>
           <KeyAttribute
               motion:motionTarget="@+id/cardView"
               motion:framePosition="0"
               android:translationX="-300dp"/>
           <KeyAttribute
               motion:motionTarget="@+id/cardView"
               motion:framePosition="0"
               android:translationX="0dp"/>
       </KeyFrameSet>

        <OnSwipe
            motion:targetId="@+id/imageView8"
            motion:autoCompleteMode="continuousVelocity"
            motion:dragDirection="dragRight"
            motion:maxAcceleration="20"
            motion:maxVelocity="20"/>



    </Transition>

    <ConstraintSet android:id="@+id/start">

        <Constraint
            android:layout_height="wrap_content"
            android:layout_marginTop="7dp"
            motion:layout_constraintTop_toTopOf="parent"
            android:layout_width="wrap_content"
            motion:layout_constraintEnd_toStartOf="@+id/imageView7"
            android:id="@+id/textView5"
            motion:layout_constraintStart_toEndOf="@+id/image8" />
        <Constraint
            android:id="@+id/image8"
            android:layout_width="55dp"
            android:layout_height="55dp"
            android:layout_marginStart="15dp"
            android:background="@color/white"
            android:src="@drawable/three_lines"
            motion:altSrc="@drawable/cancel_icon"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />
        <Constraint
            android:id="@+id/fragmentContainerView2"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="55dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintHorizontal_bias="0.5"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:navGraph="@navigation/navigation2" />
    </ConstraintSet>

    <ConstraintSet android:id="@+id/end">
        <Constraint
            android:layout_height="wrap_content"
            android:layout_marginTop="0dp"
            android:visibility="invisible"
            motion:layout_constraintTop_toTopOf="parent"
            android:layout_width="wrap_content"
            motion:layout_constraintEnd_toStartOf="@+id/imageView7"
            android:id="@+id/textView5"
            motion:layout_constraintStart_toEndOf="@+id/image8" />
        <Constraint
            android:id="@+id/image8"
            android:layout_width="55dp"
            android:layout_height="55dp"
            android:layout_marginStart="300dp"
            android:background="@color/white"
            android:src="@drawable/three_lines"
            motion:altSrc="@drawable/cancel_icon"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent" />
        <Constraint
            android:id="@+id/fragmentContainerView2"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="250dp"
            android:layout_height="750dp"
            android:layout_marginTop="55dp"
            android:layout_marginStart="400dp"
            motion:layout_constraintBottom_toBottomOf="parent"
            motion:layout_constraintEnd_toEndOf="parent"
            motion:layout_constraintHorizontal_bias="0.5"
            motion:layout_constraintStart_toStartOf="parent"
            motion:layout_constraintTop_toTopOf="parent"
            motion:navGraph="@navigation/navigation2" />

    </ConstraintSet>
</MotionScene>

这是我的主要活动。KT文件

class MainActivity : AppCompatActivity() {


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val contactus = findViewById<TextView>(R.id.contact_us)
        val drawer = findViewById<ImageView>(R.id.image8)
        val tandc = findViewById<TextView>(R.id.termsandconditions)
        val motionLayout = findViewById<MotionLayout>(R.id.motion_layout)

        contactus.setOnClickListener {

            supportFragmentManager.beginTransaction().apply {
                replace(R.id.fragmentContainerView2, contact_us_fragment())
                commit()

                motionLayout.transitionToStart()
            }
        }
        drawer.setOnClickListener {

            motionLayout.transitionToEnd()
            motionLayout.transitionToStart()
        }
        tandc.setOnClickListener {
            supportFragmentManager.beginTransaction().apply {
                replace(R.id.fragmentContainerView2, TandCFragment())
                commit()

                motionLayout.transitionToStart()

            }
        }
    }
}

是否可以设置不同的导航方案，例如从about_us fragment到家庭片段等等

Answer 1

使用导航组件和 NavHostFragment 时，您永远不会执行 FragmentTransaction。相反，您应该按照指南导航到导航中的目的地图（您在 NavHostFragment 上设置的 navigation/navigation2.xml。

contactus.setOnClickListener {
    // Use the Kotlin extension on Activity
    // to get a reference to your NavController
    val navController = findNavController(R.id.fragmentContainerView2)

    // Use the android:id associated with your contact_us_fragment
    // that needs to be in your navigation graph XML file
    navController.navigate(R.id.contact_us_fragment)

    motionLayout.transitionToStart()
}