RecyclerView 移动到 ListFragment 时会无限期加载

Question

我已经遵循了本教程：https://developer.android.com/codelabs/android-room-with-a-view-kotlin。

代码工作完美，但我想将 RecyclerView 移动到片段。 现在列表会无限期加载，并且 Logcat 中没有错误。

我在

words

功能中记录了

observe

。 它可以很好地记录 Word 对象...

移动到片段时我对代码进行了一些更改：

viewModels

->

activityViewModels

application

->

requireActivity().application

owner: this

->

viewLifecycleOwner

所有这些都没有帮助。

这是我的代码：

主要活动

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

WordListFragment

class WordListFragment: ListFragment(){
    private val wordViewModel: WordViewModel by activityViewModels {
        WordViewModelFactory((requireActivity().application as WordsApplication).repository)
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {

        val recyclerView =
            inflater.inflate(R.layout.fragment_recycler, container, false) as RecyclerView
        val adapter = WordListAdapter()
        recyclerView.adapter = adapter
        recyclerView.layoutManager = LinearLayoutManager(requireActivity())

        wordViewModel.allWords.observe(viewLifecycleOwner) { words ->
            words.let { adapter.submitList(it) }
        }

        return super.onCreateView(inflater, container, savedInstanceState)
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    android:name="com.example.android.roomwordssample.WordListFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

fragment_recycler.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.recyclerview.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/recyclerview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:listitem="@layout/recyclerview_item"
    android:padding="@dimen/big_padding"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

其余部分与原始版本相同（https://github.com/android/codelab-android-room-with-a-view/archive/kotlin.zip）

Answer 1

您只需在 onCreateView 中膨胀视图，然后在 onViewCreated 中开始执行与 recyclerView 相关的任何操作。

这是 WordListFragment 的代码：

package com.example.android.roomwordssample

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.ListFragment
import androidx.fragment.app.activityViewModels
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView


class WordListFragment: ListFragment(){
    private val wordViewModel: WordViewModel by activityViewModels {
        WordViewModelFactory((requireActivity().application as WordsApplication).repository)
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_recycler, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {

        val recyclerView: RecyclerView = view.findViewById(R.id.recyclerview)
        val adapter = WordListAdapter()
        recyclerView.adapter = adapter
        recyclerView.layoutManager = LinearLayoutManager(requireActivity())

        wordViewModel.allWords.observe(viewLifecycleOwner) { words ->
            words.let { adapter.submitList(it) }
        }


    }
}