RecyclerView Adapter not showing data-CodePudding

I'm currently learning Kotlin (specifically consuming APIs) Everything related with the API and his response is fine but I have issues showing the data in a recyclerview and the part of the adapter is little confusing. Debbuging the app step by step I can see the response body go into the adapter but nothing shows of in the recyclerview.

My MainActivity

const val BASE_URL = "https://api.themoviedb.org/"
class MainActivity : AppCompatActivity() {
    lateinit var binding: ActivityMainBinding


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(R.layout.activity_main)
        getMyData()

    }

    private fun getMyData() {
        val retrofitBuilder = Retrofit.Builder()
            .addConverterFactory(GsonConverterFactory.create())
            .baseUrl(BASE_URL)
            .build()
            .create(ApiInterface::class.java)

        val retrofitData = retrofitBuilder.getPopularMovies()
        retrofitData.enqueue(object : Callback<MoviesResponse?> {
            override fun onResponse(
                call: Call<MoviesResponse?>,
                response: Response<MoviesResponse?>
            ) {
                if(response.isSuccessful){
                    binding.rvMovie.apply{
                        setHasFixedSize(true)
                        layoutManager = LinearLayoutManager(this@MainActivity)
                        adapter = Adapter(response.body()!!.results)
                    }
                }
            }
            override fun onFailure(call: Call<MoviesResponse?>, t: Throwable) {
                Toast.makeText(this@MainActivity, "${t.message}", Toast.LENGTH_SHORT).show()
            }
        })

    }


}

MainActivity XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@ id/rvMovie"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="visible"
        >

    </androidx.recyclerview.widget.RecyclerView>

</RelativeLayout>

The Adapter

class Adapter(val movieList: List<MyDataItem>):RecyclerView.Adapter<MoviesViewHolder>(){
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MoviesViewHolder {
        val view: LayoutInflater = LayoutInflater.from(parent.context)
        return MoviesViewHolder(view.inflate(R.layout.movie_item, parent, false))
    }

    override fun onBindViewHolder(holder: MoviesViewHolder, position: Int) {
        return holder.bindInfo(movieList[position])
    }

    override fun getItemCount(): Int {
        return movieList.size
    }


}

class MoviesViewHolder(itemView : View): RecyclerView.ViewHolder(itemView) {
    private val binding = MovieItemBinding.bind(itemView)


    fun bindInfo(movie: MyDataItem) {
        Picasso.get().load("https://image.tmdb.org/t/p/w500${movie.poster_path}").into(binding.moviePhoto)
        binding.movieTitle.text = "Title: " movie.title
        binding.movieOverview.text = movie.overview
        binding.movieRating.text = "Rating : " movie.vote_average.toString()
    }
}

individual item's xml

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <ImageView
                android:layout_width="match_parent"
                android:layout_height="200dp"
                android:layout_centerHorizontal="true"
                android:id="@ id/movie_photo"
                android:contentDescription="Movie Image" />

            <TextView
                android:layout_below="@ id/movie_photo"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@ id/movie_title"
                android:layout_margin="5dp"
                android:textSize="15sp"
                android:text="Title : "/>

            <TextView
                android:layout_below="@ id/movie_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@ id/movie_overview"
                android:layout_margin="5dp"
                android:text="OverView : "/>

            <TextView
                android:layout_below="@ id/movie_overview"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@ id/movie_rating"
                android:textSize="15sp"
                android:layout_margin="5dp"
                android:text="Rating : "/>


        </RelativeLayout>

    </androidx.cardview.widget.CardView>

</RelativeLayout>

CodePudding user response：

If we have a RecyclerView with match_parent as height/width, we should add setHasFixedSize(true) since the size of the RecyclerView itself does not change inserting or deleting items into it.

setHasFixedSize should be false if we have a RecyclerView with wrap_content as height/width since each element inserted by the adapter could change the size of the Recycler depending on the items inserted/deleted, so, the size of the Recycler will be different each time we add/delete items.

To be more clear, if we use

<android.support.v7.widget.RecyclerView
    android:id="@ id/my_recycler_view"
    android:scrollbars="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

We can use rvMovie.setHasFixedSize(true)

<android.support.v7.widget.RecyclerView
        android:id="@ id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

Then, we should use rvMovie.setHasFixedSize(false) if we use wrap_content for width or height in our RecyclerView

CodePudding user response：

It may be because you're not actually linking the adapter to your recycler view?

Try adding :

recyclerView.adapter = adapter