Android导航组件未显示片段 [英] Android Navigation Component Not Displaying Fragment

问题描述

我正在尝试在现有应用中实现新的Android导航组件. 我有2个相同的片段，除了它们的名称.当我将startDestination设置为fragment2时，该片段似乎正确显示.当startDestination设置为fragment1时，我看不到膨胀视图，但确实看到了创建的Fragment 1"吐司.

I'm trying to implement the new Android Navigation Component in an existing app. I have 2 fragments that are identical except for their name. When I set the startDestination to fragment2, the fragment seems to be shown correctly. When the startDestination is set to fragment1, I don't see the inflated view but I do see the "Fragment 1 created" toast.

我做错了什么?

class Fragment1 : Fragment() {

  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
      savedInstanceState: Bundle?): View? {
    Toast.makeText(context, "Fragment 1 created", Toast.LENGTH_LONG).show()
    return inflater.inflate(R.layout.fragment1, container, false)
  }

}

class Fragment2 : Fragment() {

  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
      savedInstanceState: Bundle?): View? {
    Toast.makeText(context, "Fragment 2 created", Toast.LENGTH_LONG).show()
    return inflater.inflate(R.layout.fragment2, container, false)
  }


}

nav_graph.xml

nav_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/nav_graph"
    app:startDestination="@id/fragment1">

  <fragment
      android:id="@+id/fragment1"
      android:name="com.package.anotherpackage.ui.Fragment1"
      android:label="fragment1"
      tools:layout="@layout/fragment1"/>

  <fragment
      android:id="@+id/fragment2"
      android:name="com.package.anotherpackage.ui.Fragment2"
      android:label="fragment2"
      tools:layout="@layout/fragment2"/>
</navigation>

MainActivity布局:

MainActivity layout:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    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"
    android:background="@android:color/background_light"
    tools:context=".MainActivity">

  <fragment
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:id="@+id/nav_host_fragment"
      android:name="androidx.navigation.fragment.NavHostFragment"
      app:navGraph="@navigation/nav_graph"
      app:defaultNavHost="true"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      />

</FrameLayout>

Fragment1布局:

Fragment1 Layout:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.Fragment1"
    >

  <!-- TODO: Update blank fragment layout -->
  <TextView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:text="fragment 1"
      />

</FrameLayout>

依赖项:

//Navigation
  def nav_version = "1.0.0-alpha05"

  implementation "android.arch.navigation:navigation-fragment-ktx:$nav_version"
  implementation "android.arch.navigation:navigation-ui-ktx:$nav_version"

  // optional - Test helpers
  androidTestImplementation "android.arch.navigation:navigation-testing-ktx:$nav_version"

推荐答案

我在项目的另一个库中有一个名为"fragment1.xml"的布局. 它一定与我试图在Fragment1中充气的其他布局相冲突.重命名Fragment1布局可以解决此问题.

I had a layout in another library in my project with the name "fragment1.xml". It must have been conflicting with the other layout I was trying to inflate in Fragment1. Renaming the Fragment1 layout fixed the issue.

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