【发布时间】：2020-05-13 19:47:18
【问题描述】：
我正在开发一个新的 android 应用程序，但我的应用程序在 MainActivity 的回收器视图中显示空数据，并且我放了一个断点，那里也显示 null，但我已经在初始化数据我想知道我在哪里犯错了失踪了吗？
在我的 RestClient.kt 下
class RestClient {
internal val httpLoggingInterceptor: HttpLoggingInterceptor
get() {
val httpLoggingInterceptor = HttpLoggingInterceptor()
httpLoggingInterceptor.level = HttpLoggingInterceptor.Level.BODY
return httpLoggingInterceptor
}
internal fun getOkHttpClient(httpLoggingInterceptor: HttpLoggingInterceptor): OkHttpClient {
return OkHttpClient.Builder()
.addInterceptor(httpLoggingInterceptor)
.build()
}
companion object {
private val ROOT_URL = "http://www.mocky.io"
/**
* Get Retrofit Instance
*/
private val retrofitInstance: Retrofit
get() = Retrofit.Builder()
.baseUrl(ROOT_URL)
.addConverterFactory(GsonConverterFactory.create())
.build()
/**
* Get API Service
*
* @return API Service
*/
val apiService: RestInterface
get() = retrofitInstance.create(RestInterface::class.java)
}
}
在我的 Post.kt 数据类下面
data class Post(
@SerializedName("description")
val description: String,
@SerializedName("id")
val id: Int,
@SerializedName("image")
val image: String,
@SerializedName("published_at")
val publishedAt: String,
@SerializedName("title")
val title: String,
@SerializedName("user_id")
val userId: Int
)
在 RestList.kt 下
data class RestList(
@SerializedName("posts")
val posts: List<Post>
)
在我的界面下方
interface RestInterface {
@get:GET("/v2/59f2e79c2f0000ae29542931")
val getPosts: Call<RestList>
}
在适配器下方
class RestAdapter(val post: List<Post>?,val restList: RestList?) : RecyclerView.Adapter<RestAdapter.PostHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PostHolder {
val itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.post_list, null)
return PostHolder(itemView)
}
override fun getItemCount(): Int {
return post?.size!!
}
override fun onBindViewHolder(holder: PostHolder, position: Int) {
val posts = post?.get(position)
Picasso
.get() // give it the context
.load(posts?.image) // load the image
.into(holder.postImage)
holder.userId.text = posts?.userId.toString()
holder.postTitle.text = posts?.title
holder.postTime.text = posts?.publishedAt
holder.postDescription.text = posts?.description
}
class PostHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val postImage: ImageView
val userId: TextView
val postTitle: TextView
val postTime: TextView
val postDescription: TextView
init {
postImage = itemView.findViewById(R.id.postImage)
userId = itemView.findViewById(R.id.userId)
postTitle = itemView.findViewById(R.id.postTitle)
postTime = itemView.findViewById(R.id.postTime)
postDescription = itemView.findViewById(R.id.postDescription)
}
}
}
我在mainactivity.kt下面调用改造
class MainActivity : AppCompatActivity() {
companion object{
const val TAG = "internet"
}
private var recyclerView: RecyclerView? = null
private var restAdapter: RestAdapter? = null
private var restInterface: RestInterface? = null
private var postList: List<Post>? = null
private var restList: RestList? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recyclerView = findViewById(R.id.recycler_view)
restInterface = RestClient.apiService
val call = restInterface?.getPosts
call?.enqueue(object : Callback<RestList> {
override fun onResponse(call: Call<RestList>, response: Response<RestList>) {
if (response.body() != null) {
restList = response.body()
val layoutManager = LinearLayoutManager(applicationContext)
recyclerView?.layoutManager = layoutManager
// initialize postList with posts
postList = restList?.posts
restAdapter = RestAdapter(postList, restList)
//this should be come later
recyclerView?.adapter = restAdapter
}
}
override fun onFailure(call: Call<RestList>, t: Throwable) {
Log.e(TAG, "There is no internet connection")
}
})
}
}
在我的 activity_main.xml 下方
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent">
</androidx.recyclerview.widget.RecyclerView>
</LinearLayout>
在 post_list.xml 下方
<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="wrap_content"
android:background="@color/colorWhite">
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline"
android:layout_width="0dp"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.55" />
<ImageView
android:id="@+id/postImage"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_margin="16dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintDimensionRatio="16:9"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toEndOf="@id/guideline"
app:layout_constraintTop_toTopOf="parent"
tools:ignore="ContentDescription" />
<TextView
android:id="@+id/userId"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="25dp"
android:layout_marginLeft="25dp"
android:layout_marginTop="10dp"
android:text="Placeholder"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/postTitle"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text="Secondary"
app:layout_constraintEnd_toStartOf="@id/postImage"
app:layout_constraintStart_toStartOf="@id/userId"
app:layout_constraintTop_toBottomOf="@id/userId" />
<TextView
android:id="@+id/postTime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:layout_marginBottom="10dp"
android:text="Tertiary"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="@id/userId"
app:layout_constraintTop_toBottomOf="@id/postTitle" />
<TextView
android:id="@+id/postDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:layout_marginBottom="10dp"
android:text="Tertiary"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="@id/userId"
app:layout_constraintTop_toBottomOf="@id/postTime" />
</androidx.constraintlayout.widget.ConstraintLayout>
【问题讨论】：
-
你能添加你的布局吗？
-
我认为您的
postList是null因为您没有分配任何值。使用此Log.e("pastist",Gson().toJson(postList))检查帖子列表是否包含数据 -
@Md.Asaduzzaman 我已添加请查看
标签： android kotlin android-recyclerview retrofit