RecyclerView.ViewHolder and Adapter demonstration

BaseAdapter.java

public abstract class BaseAdapter<T, VH extends BaseViewHolder<T>> extends RecyclerView.Adapter<VH> {
	
	private List<T> items;

	// Missing: setItems(), addItem(), removeItem(), ...

  	@Override
  	public final void onBindViewHolder(VH vh, int position) {
 		T item = items.get(position);
    		vh.performBind(item, position);
  	}
}

BaseViewHolder.java

public abstract class BaseViewHolder<T> extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {

	private T item;

	protected BaseViewHolder(ViewGroup parent, @LayoutRes int itemLayoutId) {
		super(LayoutInflater.from(parent.getContext()).inflate(itemLayoutId, parent, false));
		
		// Bind instance views and attach listeners to the itemView (this field is provided by RecyclerView.ViewHolder itself)
		ButterKnife.bind(this, itemView);
		itemView.setOnClickListener(this);
		itemView.setOnLongClickListener(this);
	}

	protected final void performBind(T item, int position) {
		this.item = item;
		onBind(item, position);
	}
	
	protected T getItem() {
	  return item;
	}

	protected abstract void onBind(T item, int position);
	protected abstract void onClick(View view, T item);
	protected abstract void onLongClick(View view, T item);

	@Override
	public final void onClick(View view) {
	  onClick(view, item);
	}

	@Override public final boolean onLongClick(View view) {
	  return onLongClick(view, item);
	}

Demo.java

/**
 * Just some demo POJO to populate a list with.
 */
public class Demo {
	
	public final String name;
	public final String url;
	public final float value;
	
	public Demo(String name, String url, float value) {
		this.name = name;
		this.url = url;
		this.value = value;
	}
}

DemoAdapter.java

public class DemoAdapter extends BaseAdapter<Demo, DemoViewHolder> {
	
	@Override
	public final DemoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
		return new DemoViewHolder(parent);
	}
}

DemoViewHolder.java

public class DemoViewHolder extends BaseViewHolder<Demo> {
	
	@Bind(R.id.textview_name)
	TextView tvName;
	@Bind(R.id.imageview_url)
	ImageView ivUrl;
	@Bind(R.id.imageview_context_menu)
	ImageView ivContextMenu;
	
	public DemoViewHolder(ViewGroup parent) {
		// Call through to super constructor; ButterKnife will have bound instance fields after this
		super(parent, R.layout.item_demo);
		
		// Without ButterKnife, this would be where you findViewById on the itemView,
		// e.g. tvName = (TextView) itemView.findViewById(R.id.textview_name);
		
		// Now, add more listeners, if needed
		ivContextMenu.setOnClickListener((view) -> {
			// Do something specific when clicking this ImageView specifically.
			// If you need to grab the ViewHolder's current item,
			// use the base class method getItem().
		});
	}
	
	@Override
	public void onBind(Demo item, int position) {
		tvName.setText(item.name);
		Glide.with(ivUrl.getContext()).load(item.url).into(ivUrl);
	}
	
	@Override
	public void onClick(View view, Demo item) {
		// Do something on click!
		// Maybe use a Bus mechanism (connected to the outer Activity/Fragment) to propagate the event?
		// This could be passed in from the adapter in the constructor, for instance.
		// bus.post(new OnDemoClicked(item));
	}
	
	@Override
	public void onLongClick(View view, Demo item) {
		// If you want additional behaviour upon long-clicking the item
	}
}

hi,
could you please be more elaborate on the bus mechanism. What i am trying to do is, on click of a button attached to each recyclerview item , I want to open a dialog which includes another recyclerview much like the Facebook UI. But I am unable to set the adapter despite the code of the dialog recyclerview being roughly same as that of my activty recyclerview. Would be grateful if you could help. Thanks!

protected abstract void onLongClick(View view, T item);

this should be

protected abstract boolean onLongClick(View view, T item);