Android Kotlin Recycle View reloadData

Question

I have "problem" with this:

,

where P button is Previous, and N as Next, both button call:

private fun fetchJson(date: String) {
        val url = "https://xxx/$date.json"
        println("URL: $url")
        val request = Request.Builder().url(url).build()
        val client = OkHttpClient()
        client.newCall(request).enqueue(object: Callback {

            override fun onResponse(call: Call, response: Response) {
                val responseData = response.body()?.string()

                runOnUiThread {
                    var rows: List<Product> = emptyList()

                    try {
                        if (response.code() in 200..399) {
                            val gson = GsonBuilder().create()
                            rows = gson.fromJson(responseData, Array<Product>::class.java).toList()

                            recycleView.adapter = ProductsAdapter(this@DetailsActivity, rows)
                            (recycleView.adapter as ProductsAdapter).notifyDataSetChanged()

                        }
                    } catch (e: JSONException) {
                        e.printStackTrace()
                    }
                }

            }

            override fun onFailure(call: Call, e: IOException) {
                println("Failed")
            }
        })
    }

and Products Adapter Class

class ProductsAdapter(private val context: Context, private val rows: List<Product>): RecyclerView.Adapter<ProductsAdapter.ProductViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {
        val view = LayoutInflater.from(context).inflate(R.layout.product_item, parent, false)
        return ProductViewHolder(view)
    }

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

    override fun onBindViewHolder(holder: ProductViewHolder, position: Int) {
        val row = rows[position]
        holder.setData(row, position)
    }

    inner class ProductViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
        fun setData(row: Product, position: Int) {
            /// set data
        }
    }
}

also XML for recycle view is:

<androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycleView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#E9DA1616"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/vipBtn" />

and the main problem is when tap on N or P button, data is there but recyclerView did not reload with new data. Only show product (populate recyclerview) first time.

Where I go wrong? I just start with Android and Kotlin, every tutorial says notifyDataSetChanged() this will do the job, but not...

Thanks

Answer 1

Maybe try recyclerView.invalidate() after pass new data

Answer 2

Wow! Just wow!

I have some experience in iOS and this is literally my 10th hour of Android development, but this is so strange.

My layout from question is constraint layout:

<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="match_parent"
    android:background="@color/colorPrimary"
    tools:context=".DetailsActivity">
[...]

I just change to relative layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#0A7463">
[...]

and now it's working. Amazing.

This is strange that layout define behavior of component.

Answer 3

To Reload the data in recyclerview you can use below things. First, add this method in your adapter class.

public fun setData(rowData:List<Product>){
   this.row = rowData
   notifyDataSetChanged()
}

After that below these lines in

private fun fetchJson(date: String) {
    val url = "https://xxx/$date.json"
    println("URL: $url")
    val request = Request.Builder().url(url).build()
    val client = OkHttpClient()
    client.newCall(request).enqueue(object: Callback {

        override fun onResponse(call: Call, response: Response) {
            val responseData = response.body()?.string()

            runOnUiThread {
                var rows: List<Product> = emptyList()

                try {
                    if (response.code() in 200..399) {
                        val gson = GsonBuilder().create()
                        rows = gson.fromJson(responseData,Array<Product>::class.java).toList()

                        recycleView.adapter.setData(rows)


                    }
                } catch (e: JSONException) {
                    e.printStackTrace()
                }
            }

        }

        override fun onFailure(call: Call, e: IOException) {
            println("Failed")
        }
    })
}