2020-07-03-Android-Kotlin-RecyclerView-PullToRefresh

build.gradle (Module: app)

dependencies {
    ...
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.0.0'
    ...
}

List Item

data class ListItem (
    val title: String,
    val subtitle: String
)

MainListAdaptor.kt

class MainListAdapter (
    private val list: List<ListItem>
): RecyclerView.Adapter<MainListAdapter.ViewHolder>() {

    class ViewHolder(view: View): RecyclerView.ViewHolder(view)

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MainListAdapter.ViewHolder {
        return ViewHolder(
            LayoutInflater
                .from(parent.context)
                .inflate(R.layout.list_main, parent, false)
        )
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.itemView.title.text = list[position].title
        holder.itemView.subtitle.text = list[position].subtitle
        Glide.with(holder.itemView)  // glide with this view
            .load(list[position].subtitle) // download using this url
            .override(250, 250) // set this size
            .placeholder(R.mipmap.ic_launcher) // default placeHolder image
            .error(R.mipmap.ic_launcher) // use this image if faile
            .into(holder.itemView.imageView) // set
    }

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

MainActivity.kt

class User(
    val login: String,
    val id: Int,
    val avatar_url: String
)

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        listView.adapter = MainListAdapter(listOf<ListItem>(ListItem("Sagar", "Kothari")))
        swipeRefresh.setOnRefreshListener {
            getUsers()
        }
        getUsers()
    }

    fun getUsers() {
        swipeRefresh.isRefreshing = true
        listView.adapter = MainListAdapter(listOf<ListItem>())
        val queue = Volley.newRequestQueue(this)
        val url = "https://api.github.com/users"
        val stringRequest = StringRequest(Request.Method.GET, url, Response.Listener {
            val gson = Gson()
            val arrayUsers = object : TypeToken<Array<User>>() {}.type
            var users: Array<User> = gson.fromJson(it,  arrayUsers)
            val list = users.map { ListItem(it.login, it.avatar_url) }
            listView.adapter = MainListAdapter(list)
            swipeRefresh.isRefreshing = false
        }, Response.ErrorListener {
            println("Failed Getting users")
            Toast.makeText(this, "Something went wrong. Please try again.", Toast.LENGTH_SHORT)
            swipeRefresh.isRefreshing = false
        })
        queue.add(stringRequest)
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context=".MainActivity">

    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
        android:id="@+id/swipeRefresh"
        android:layout_width="wrap_content"
        android:layout_height="0px"
        android:layout_weight="1">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

</androidx.constraintlayout.widget.ConstraintLayout>