EndlessRecyclerViewAdapter.java

package org.maepaysoh.maepaysoh.adapters;

import android.content.Context;
import android.graphics.PorterDuff;
import android.support.annotation.LayoutRes;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import java.util.concurrent.atomic.AtomicBoolean;
import org.maepaysoh.maepaysoh.R;

import static android.support.v7.widget.RecyclerView.Adapter;
import static android.support.v7.widget.RecyclerView.ViewHolder;

/**
 * @author rockerhieu on 7/6/15.
 */
public class EndlessRecyclerViewAdapter extends RecyclerViewAdapterWrapper {
  public static final int TYPE_PENDING = 999;
  private final Context context;
  private final int pendingViewResId;
  private AtomicBoolean keepOnAppending;
  private AtomicBoolean dataPending;
  private RequestToLoadMoreListener requestToLoadMoreListener;

  public EndlessRecyclerViewAdapter(Context context, Adapter wrapped,
      RequestToLoadMoreListener requestToLoadMoreListener, @LayoutRes int pendingViewResId,
      boolean keepOnAppending) {
    super(wrapped);
    this.context = context;
    this.requestToLoadMoreListener = requestToLoadMoreListener;
    this.pendingViewResId = pendingViewResId;
    this.keepOnAppending = new AtomicBoolean(keepOnAppending);
    dataPending = new AtomicBoolean(false);
  }

  public EndlessRecyclerViewAdapter(Context context, Adapter wrapped,
      RequestToLoadMoreListener requestToLoadMoreListener) {
    this(context, wrapped, requestToLoadMoreListener, R.layout.item_loading, true);
  }

  private void stopAppending() {
    setKeepOnAppending(false);
  }

  /**
   * Let the adapter know that data is load and ready to view.
   *
   * @param keepOnAppending whether the adapter should request to load more when scrolling to the
   * bottom.
   */
  public void onDataReady(boolean keepOnAppending) {
    dataPending.set(false);
    setKeepOnAppending(keepOnAppending);
  }

  private void setKeepOnAppending(boolean newValue) {
    keepOnAppending.set(newValue);
    getWrappedAdapter().notifyDataSetChanged();
  }

  /**
   *
   */
  public void restartAppending() {
    dataPending.set(false);
    setKeepOnAppending(true);
  }

  private View getPendingView(ViewGroup viewGroup) {
    return LayoutInflater.from(context).inflate(pendingViewResId, viewGroup, false);
  }

  @Override public int getItemCount() {
    return super.getItemCount() + (keepOnAppending.get() ? 1 : 0);
  }

  @Override public int getItemViewType(int position) {
    if (position == getWrappedAdapter().getItemCount()) {
      return TYPE_PENDING;
    }
    return super.getItemViewType(position);
  }

  @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == TYPE_PENDING) {
      return new PendingViewHolder(getPendingView(parent));
    }
    return super.onCreateViewHolder(parent, viewType);
  }

  @Override public void onBindViewHolder(ViewHolder holder, int position) {
    if (getItemViewType(position) == TYPE_PENDING && !dataPending.get()) {
      dataPending.set(true);
      requestToLoadMoreListener.onLoadMoreRequested();
    } else {
      super.onBindViewHolder(holder, position);
    }
  }

  public interface RequestToLoadMoreListener {
    /**
     * The adapter requests to load more data.
     */
    void onLoadMoreRequested();
  }

  class PendingViewHolder extends ViewHolder {

    public PendingViewHolder(View itemView) {
      super(itemView);
      ((ProgressBar) itemView).getIndeterminateDrawable()
          .setColorFilter(context.getResources().getColor(R.color.primary),
              PorterDuff.Mode.SRC_ATOP);
    }
  }
}