Navigation Component: how to navigate from activity to a fragment

问题

I want to navigate on click FAB in (activity) to New fragment 1.

in my code fab button in the main activity common for all pages. could anyone guide me?

activity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
    tools:context=".MainActivity">

    <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:navGraph="@navigation/mobile_navigation" />

    <com.google.android.material.bottomappbar.BottomAppBar
        android:id="@+id/bottomAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:navigationIcon="@drawable/ic_baseline_dashboard_24"
        app:navigationContentDescription="Navigation icon"
        />
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/floatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/bottomAppBar"
        android:backgroundTint="@color/colorPrimary"
        style="@style/Widget.App.FloatingActionButton"
        app:srcCompat="@drawable/menu_bug" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

graph.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/navigation_home">

    <fragment
        android:id="@+id/navigation_home"
        android:name="com.androidfeby.bugreport.ui.home.HomeFragment"
        android:label="@string/title_home"
        tools:layout="@layout/fragment_home" />

    <fragment
        android:id="@+id/navigation_report"
        android:name="com.androidfeby.bugreport.ui.report.FragmentReport"
        android:label="@string/title_dashboard"
        tools:layout="@layout/fragment_report" />

    <fragment
        android:id="@+id/navigation_notifications"
        android:name="com.androidfeby.bugreport.ui.history.NotificationsFragment"
        android:label="@string/title_notifications"
        tools:layout="@layout/fragment_notifications" />
</navigation>

requirement: if I click on fab button just navigate to fragment "navigation_report" which is in the graph

回答1:

MainActivity : XML navigate to a new fragment, when on click fab button

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
    tools:context=".MainActivity">

    <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:navGraph="@navigation/mobile_navigation" />

    <com.google.android.material.bottomappbar.BottomAppBar
        android:id="@+id/bottomAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:navigationIcon="@drawable/ic_dashboard_svgrepo_com"
        app:navigationContentDescription="Navigation icon"
        />
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/floatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/bottomAppBar"
        android:backgroundTint="@color/colorPrimary"
        style="@style/Widget.App.FloatingActionButton"
        app:srcCompat="@drawable/menu_bug" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

MainActivity : KT

    val navController = findNavController(R.id.nav_host_fragment)
// MainActivity : onCreate
// in my code fab button in the main activity common for all fragment. 
        floatingActionButton.setOnClickListener {
            navController.navigateUp() // to clear previous navigation history
            navController.navigate(R.id.new_issue)
        }

// plz suggest me any better solution on this.

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/home">

    <fragment
        android:id="@+id/home"
        android:name="com.androidfeby.bugreport.FragmentHome"
        android:label="@string/title_home"
        tools:layout="@layout/fragment_home" >
    </fragment>

    <fragment
        android:id="@+id/new_issue"
        android:name="com.androidfeby.bugreport.FragmentNewIssue"
        android:label="@string/title_dashboard"
        tools:layout="@layout/fragment_report" />

    <fragment
        android:id="@+id/history"
        android:name="com.androidfeby.bugreport.FragmentHistory"
        android:label="@string/title_notifications"
        tools:layout="@layout/fragment_notifications" />
</navigation>

来源：https://stackoverflow.com/questions/63007726/navigation-component-how-to-navigate-from-activity-to-a-fragment