Android Navigation 使用總結

1.導包

implementation ‘androidx.navigation:navigation-fragment-ktx:2.3.1’
implementation ‘androidx.navigation:navigation-ui-ktx:2.3.1’

2.1 建立 Navigation 入口

在Activity布局檔案中建立Fragmeng，必須位NavHostFragment

    <fragment
        android:id="@+id/nav_register_frag"
        android:fitsSystemWindows="true"
     	android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        app:defaultNavHost="true"
        android:layout_height="match_parent"
        app:navGraph="@navigation/nav_register" />

• app:defaultNavHost="true"
  設定 Navigation的回傳模式，true表明Fragment之間按回傳鍵 回傳上一個Fragment；false 表示直接退出Activity，
• app:navGraph="@navigation/nav_register"
  指定的 Navigation xml 檔案，

2.2 新建 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/nav_register"
    app:startDestination="@id/enterPhoneFragment">

    <fragment
        android:id="@+id/enterPhoneFragment"
        android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterPhoneFragment"
        android:label="EnterPhoneFragment"
        tools:layout="@layout/frag_enter_phone">
        <action
            android:id="@+id/action_enterPhoneFragment_to_enterCodeFragment"
            app:destination="@id/enterCodeFragment" />
    </fragment>
    <fragment
        android:id="@+id/enterCodeFragment"
        android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterCodeFragment"
        android:label="EnterCodeFragment"
        tools:layout="@layout/frag_enter_code">
        <action
            app:popUpTo="@id/enterCodeFragment"
            app:popUpToInclusive="true"
            android:id="@+id/action_enterCodeFragment_to_enterPwdFragment"
            app:destination="@id/enterPwdFragment" />
    </fragment>
    <fragment
        android:id="@+id/enterPwdFragment"
        android:name="com.pqtel.pqsecuritysaw.ui.reg.EnterPwdFragment"
        android:label="EnterPwdFragment"
        tools:layout="@layout/frag_enter_pwd" />
</navigation>

• app:startDestination="@id/enterPhoneFragment"
  主入口，也就是首頁面必須指定 否則報錯，
• app:destination="@id/enterCodeFragment"
  Action 跳轉動作 跳轉的目的Fragment
• app:popUpTo="@id/enterCodeFragment"
  app:popUpToInclusive="true"
  一般一起使用如果設定了app:defaultNavHost="true"
  理論上的跳轉A-B-C，按下回傳時候是C-B-A
  若B到C的Action設定了這兩條屬性，則回傳變成了C-A，B被出堆疊了，
  

2.3 BottomNavigation與Navigation

可以用此組合替代 viewpager和Tablayout
activity.xml

 <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/bottom_nav_menu" />

    <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_constraintBottom_toTopOf="@id/nav_view"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />

navigation.xml

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

    <fragment
        android:id="@+id/navigation_dashboard"
        android:name="com.pqtel.navtest.ui.dashboard.DashboardFragment"
        android:label="@string/title_dashboard"
        tools:layout="@layout/fragment_dashboard" />

    <fragment
        android:id="@+id/navigation_notifications"
        android:name="com.pqtel.navtest.ui.notifications.NotificationsFragment"
        android:label="@string/title_notifications"
        tools:layout="@layout/fragment_notifications" />

注意這里的fragment id 需要與menuitem id 一一對用，否則無法跳轉