android - 将 fragment 加载到Kotlin的 fragment 中

Question

我想到一个应用程序结构:

DashBoard Activity

HomeFragment

AdsFragment

GreetingFragment

ExperienceFragment

考虑到这一点，我试图在HomeFragment中加载不同的片段，这也是一个片段

我已经在HomeFragment的onCreateView()中编写了以下代码

val fm : FragmentManager = childFragmentManager
        val container = R.id.greetingFragmentContainer
        val greetingFragment : Fragment? = fm.findFragmentById(R.id.fragmentGreeting)
        if (greetingFragment != null) {
            fm.beginTransaction().replace(container, greetingFragment).commit()
        } else {
            Log.e("HomeFragment", "Fragment not found")
        }

fragment_greeting.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    android:id="@+id/fragmentGreeting"
    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="._fragments.dash.GreetingFragment">

    <ImageView
        android:id="@+id/profile_image"
        android:layout_width="96dp"
        android:layout_height="96dp"
        android:src="@drawable/loading"/>

</FrameLayout>

使用该if语句，我发现greetingFragment值返回null。

我究竟做错了什么？

Answer 1

在HomeFragment中尝试一下

lateinit var context: AppCompatActivity

    override fun onAttach(context: Context) {
        super.onAttach(context)
        this.context = context as AppCompatActivity
    }

然后调用不含findFragmentbyId的片段，如下所示:

 val fm = context.supportFragmentManager
            val fragmentTransaction: FragmentTransaction
            val fragment = GreetingFragment()
            fragmentTransaction = fm.beginTransaction()
            fragmentTransaction.replace(R.id.container, fragment)
                .addToBackStack(null)
            fragmentTransaction.commit()