Question

我正在尝试连接Android导航组件和BottomNavigationView。

如何避免重新创建片段？我读了很多文章，看到了很多代码示例，但是我自己找不到解决问题的方法。

我尝试为自己实现this方法，但是片段没有切换。

每个容器（家庭，字典和聊天室）将包含许多片段，因此，this方法似乎无关紧要。

现在我的代码：

MainActivity.kt

class MainActivity : AppCompatActivity() {

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

        setSupportActionBar(toolbar)
        if (savedInstanceState == null) {
            setupBottomNavigation()
        }
    }

    override fun onRestoreInstanceState(savedInstanceState: Bundle) {
        super.onRestoreInstanceState(savedInstanceState)
        setupBottomNavigation()
    }

    private fun setupBottomNavigation() {
        val bottomNavigationView = findViewById<BottomNavigationView>(R.id.bottom_navigation)
        val navHostFragment = supportFragmentManager.findFragmentById(R.id.my_nav_host_fragment) as NavHostFragment
        NavigationUI.setupWithNavController(bottomNavigationView, navHostFragment.navController)
    }
}

activity_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"
    tools:context=".views.base.MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/my_nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/home_navigation" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/color_primary"
        app:itemIconTint="@color/color_bottom_navigation"
        app:itemTextColor="@color/color_bottom_navigation"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_navigation_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

bottom_navigation_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/homeFragment"
        android:title="@string/home"
        android:icon="@drawable/ic_home"/>

    <item
        android:id="@+id/dictionaryFragment"
        android:title="@string/dictionary"
        android:icon="@drawable/ic_today"/>

    <item
        android:id="@+id/communicationFragment"
        android:title="@string/chat"
        android:icon="@drawable/ic_chat"/>
</menu>

有人可以建议或演示如何解决该问题吗？

具有BottomNavigationView的导航架构组件重新创建片段

0 个答案: