Created
September 28, 2017 09:40
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Simple End-less RecyclerView Adapter (Kotlin)
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| package mdzzohrabi.adapter | |
| import android.support.v7.widget.RecyclerView | |
| import java.util.ArrayList | |
| /** | |
| * Endless Recycler view adapter | |
| * @author Masoud Zohrabi <mdzzohrabi@gmail.com> | |
| */ | |
| abstract class EndlessAdapter<VH: RecyclerView.ViewHolder, T>: RecyclerView.Adapter<VH>() { | |
| // Adapter loaded items | |
| private val items: ArrayList<T> = ArrayList() | |
| // Get items loading threshold | |
| protected open fun getThreshold(): Int = 5 | |
| override fun onBindViewHolder(holder: VH, position: Int) { | |
| if ( position >= ( items.size - getThreshold() ) ) { | |
| load( items.size ) | |
| } | |
| } | |
| override fun onAttachedToRecyclerView(recyclerView: RecyclerView?) { | |
| super.onAttachedToRecyclerView(recyclerView) | |
| load(items.size) | |
| } | |
| override fun getItemCount(): Int = items.size | |
| // Insert item to loaded items | |
| protected fun insert(item: T) { items.add(item) } | |
| // Clear loaded items | |
| protected fun clearItems() { items.clear() } | |
| // Get loaded items | |
| protected fun getItems() = items | |
| // Get loaded item by position | |
| protected fun getItem(position: Int): T = items[position] | |
| // Load items called when needed to load more items | |
| abstract fun load(offset: Int, listener: OnLoadListener? = null) | |
| abstract class OnLoadListener { | |
| open fun onDataChanged() {} | |
| open fun onDataReceive() {} | |
| } | |
| } |
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| package mdzzohrabi.adapter | |
| import android.content.Context | |
| import android.os.Build | |
| import android.support.v7.widget.RecyclerView | |
| import android.transition.TransitionManager | |
| import android.view.LayoutInflater | |
| import android.view.ViewGroup | |
| import com.android.volley.Request | |
| import com.android.volley.RequestQueue | |
| import com.android.volley.Response | |
| import com.android.volley.toolbox.JsonObjectRequest | |
| import com.android.volley.toolbox.Volley | |
| import org.json.JSONObject | |
| class ExampleEndlessRecycler() : EndlessAdapter<ContentViewHolder, JSONObject>() { | |
| private val limit = 10 | |
| private val queue: RequestQueue = Volley.newRequestQueue(this.context) | |
| override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ContentViewHolder { | |
| val view = LayoutInflater.from(parent.context) | |
| .inflate(R.layout.fragment_content, parent, false) | |
| return ContentViewHolder(view as ViewGroup) | |
| } | |
| override fun onBindViewHolder(holder: ContentViewHolder, position: Int) { | |
| super.onBindViewHolder(holder, position) | |
| val content = getItem(position) | |
| // Bind item to view | |
| holder.bind(content) | |
| } | |
| fun refresh(callback: OnRefreshListener? = null) { | |
| load(0, object: OnLoadListener() { | |
| override fun onDataChanged() { callback?.onRefresh() } | |
| override fun onDataReceive() { clearItems() } | |
| }) | |
| } | |
| override fun load(offset: Int, listener: OnLoadListener?) { | |
| val url = API.Builder(API.LATEST_CONTENTS) | |
| .appendQueryParameter("topic", filters.topicId) | |
| .appendQueryParameter("offset", offset.toString()) | |
| .appendQueryParameter("limit", limit.toString()) | |
| .build().toString() | |
| val request = JsonObjectRequest( | |
| Request.Method.GET, | |
| url, | |
| null, | |
| Response.Listener<JSONObject> { response -> | |
| listener?.onDataReceive() | |
| // Add received contents to cached contents | |
| response.getJSONArray("contents").let { | |
| (0 until it.length()) | |
| .forEach { i -> insert( it.getJSONObject(i) ) } | |
| } | |
| notifyDataSetChanged() | |
| listener?.onDataChanged() | |
| }, Response.ErrorListener { }) | |
| queue.add(request) | |
| queue.start() | |
| } | |
| interface OnRefreshListener { | |
| fun onRefresh() | |
| } | |
| } |
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