如何解决如何使我的recyclerview正确显示我从Retrofit接收的数据?
从改造中获取数据,但不会显示在屏幕上。
过去几天我一直在学习实时数据和改造,我正在尽力将其与recyclerview结合使用,但是我在MainActivity.kt中弄乱了地方。我已经花了几个小时尝试自己获取它,但是我还没有找到解决我特定问题的方法。我相信我的错误可能出在代码的Lateinit部分,还是我的initRecyclerView函数。
MainActivity.kt
txt = u"565543"
x = txt.isnumeric()
print(x)
AlbumsAdapter.kt
package com.dev20.retrofitpractice
import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.LiveData
import androidx.lifecycle.Observer
import androidx.lifecycle.liveData
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.activity_main.*
import retrofit2.Response
class MainActivity : AppCompatActivity() {
private lateinit var albumsAdapter: AlbumsAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val list = ArrayList<AlbumsItem>()
initRecyclerView()
getData()
albumsAdapter = AlbumsAdapter(list)
}
private fun getData() {
val retService: AlbumService = RetrofitInstance
.getRetrofitInstance()
.create(AlbumService::class.java)
val responseLiveData: LiveData<Response<Albums>> = liveData {
val response = retService.getAlbums()
emit(response)
}
responseLiveData.observe(this,Observer {
val albumsList: MutableListIterator<AlbumsItem>? = it.body()?.listIterator()
if (albumsList != null) {
while (albumsList.hasNext()) {
val albumsItem: AlbumsItem = albumsList.next()
Log.i("MYTAG",albumsItem.title)
}
}
})
}
private fun initRecyclerView() {
recycler_view.apply {
layoutManager = LinearLayoutManager(this@MainActivity)
adapter = albumsAdapter
}
}
}
Albums.kt
package com.dev20.retrofitpractice
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.albums_list.view.*
class AlbumsAdapter(private val albumsList: List<AlbumsItem>) : RecyclerView.Adapter<AlbumsAdapter.AlbumsViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup,viewType: Int): AlbumsViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.albums_list,parent,false)
return AlbumsViewHolder(itemView)
}
override fun onBindViewHolder(holder: AlbumsViewHolder,position: Int) {
val currentItem = albumsList[position]
holder.textViewAlbums.text = currentItem.title
}
override fun getItemCount() = albumsList.size
class AlbumsViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val textViewAlbums: TextView = itemView.text_view_albums
}
}
AlbumsItem.kt
package com.dev20.retrofitpractice
class Albums : ArrayList<AlbumsItem>()
AlbumService.kt
package com.dev20.retrofitpractice
import com.google.gson.annotations.SerializedName
data class AlbumsItem(
@SerializedName("id")
val id: Int,@SerializedName("title")
val title: String,@SerializedName("userId")
val userId: Int
)
activity_main.xml
package com.dev20.retrofitpractice
import retrofit2.Response
import retrofit2.http.GET
interface AlbumService {
//define abstract function to get albums data
//returns retrofit response of type Albums
//Use suspend modifier because we are using coroutines with retrofit
@GET("/albums")
suspend fun getAlbums() :Response<Albums>
}
ablums_list.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:padding="4dp"
android:clipToPadding="false"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:listitem="@layout/albums_list"/>
</androidx.constraintlayout.widget.ConstraintLayout>
解决方法
MainActivity oncreate添加:
albumsAdapter = AlbumAdapter(albumList)
,
您的适配器未初始化。尝试初始化它。并请注意,通过构造函数传递列表不是最佳方法。假设您有一个要更新的列表,是否每次都要对适配器进行初始化?没有!因此,您应该做的是创建一个单独的方法来将列表设置为Adapter。
更新
您要为适配器设置一个空列表,然后将列表传递给适配器。所以像这样安排您的代码:-
initRecyclerView()
getData()
albumsAdapter = AlbumsAdapter(list)
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