Eu tive o mesmo problema no Lollipop e criei duas abordagens para envolver o Recyclerviewadaptador. Um é bastante fácil de usar, mas não tenho certeza de como ele se comportará com um conjunto de dados alterado. Porque envolve seu adaptador e você precisa chamar métodos como notifyDataSetChangedo objeto-adaptador correto.
O outro não deve ter esses problemas. Apenas deixe seu adaptador regular estender a classe, implementar os métodos abstratos e você deverá estar pronto. E aqui estão eles:
gists
HeaderRecyclerViewAdapterV1
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;
/**
* Created by sebnapi on 08.11.14.
* <p/>
* This is a Plug-and-Play Approach for adding a Header or Footer to
* a RecyclerView backed list
* <p/>
* Just wrap your regular adapter like this
* <p/>
* new HeaderRecyclerViewAdapterV1(new RegularAdapter())
* <p/>
* Let RegularAdapter implement HeaderRecyclerView, FooterRecyclerView or both
* and you are ready to go.
* <p/>
* I'm absolutely not sure how this will behave with changes in the dataset.
* You can always wrap a fresh adapter and make sure to not change the old one or
* use my other approach.
* <p/>
* With the other approach you need to let your Adapter extend HeaderRecyclerViewAdapterV2
* (and therefore change potentially more code) but possible omit these shortcomings.
* <p/>
* TOTALLY UNTESTED - USE WITH CARE - HAVE FUN :)
*/
public class HeaderRecyclerViewAdapterV1 extends RecyclerView.Adapter {
private static final int TYPE_HEADER = Integer.MIN_VALUE;
private static final int TYPE_FOOTER = Integer.MIN_VALUE + 1;
private static final int TYPE_ADAPTEE_OFFSET = 2;
private final RecyclerView.Adapter mAdaptee;
public HeaderRecyclerViewAdapterV1(RecyclerView.Adapter adaptee) {
mAdaptee = adaptee;
}
public RecyclerView.Adapter getAdaptee() {
return mAdaptee;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_HEADER && mAdaptee instanceof HeaderRecyclerView) {
return ((HeaderRecyclerView) mAdaptee).onCreateHeaderViewHolder(parent, viewType);
} else if (viewType == TYPE_FOOTER && mAdaptee instanceof FooterRecyclerView) {
return ((FooterRecyclerView) mAdaptee).onCreateFooterViewHolder(parent, viewType);
}
return mAdaptee.onCreateViewHolder(parent, viewType - TYPE_ADAPTEE_OFFSET);
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (position == 0 && holder.getItemViewType() == TYPE_HEADER && useHeader()) {
((HeaderRecyclerView) mAdaptee).onBindHeaderView(holder, position);
} else if (position == mAdaptee.getItemCount() && holder.getItemViewType() == TYPE_FOOTER && useFooter()) {
((FooterRecyclerView) mAdaptee).onBindFooterView(holder, position);
} else {
mAdaptee.onBindViewHolder(holder, position - (useHeader() ? 1 : 0));
}
}
@Override
public int getItemCount() {
int itemCount = mAdaptee.getItemCount();
if (useHeader()) {
itemCount += 1;
}
if (useFooter()) {
itemCount += 1;
}
return itemCount;
}
private boolean useHeader() {
if (mAdaptee instanceof HeaderRecyclerView) {
return true;
}
return false;
}
private boolean useFooter() {
if (mAdaptee instanceof FooterRecyclerView) {
return true;
}
return false;
}
@Override
public int getItemViewType(int position) {
if (position == 0 && useHeader()) {
return TYPE_HEADER;
}
if (position == mAdaptee.getItemCount() && useFooter()) {
return TYPE_FOOTER;
}
if (mAdaptee.getItemCount() >= Integer.MAX_VALUE - TYPE_ADAPTEE_OFFSET) {
new IllegalStateException("HeaderRecyclerViewAdapter offsets your BasicItemType by " + TYPE_ADAPTEE_OFFSET + ".");
}
return mAdaptee.getItemViewType(position) + TYPE_ADAPTEE_OFFSET;
}
public static interface HeaderRecyclerView {
public RecyclerView.ViewHolder onCreateHeaderViewHolder(ViewGroup parent, int viewType);
public void onBindHeaderView(RecyclerView.ViewHolder holder, int position);
}
public static interface FooterRecyclerView {
public RecyclerView.ViewHolder onCreateFooterViewHolder(ViewGroup parent, int viewType);
public void onBindFooterView(RecyclerView.ViewHolder holder, int position);
}
}
HeaderRecyclerViewAdapterV2
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;
/**
* Created by sebnapi on 08.11.14.
* <p/>
* If you extend this Adapter you are able to add a Header, a Footer or both
* by a similar ViewHolder pattern as in RecyclerView.
* <p/>
* If you want to omit changes to your class hierarchy you can try the Plug-and-Play
* approach HeaderRecyclerViewAdapterV1.
* <p/>
* Don't override (Be careful while overriding)
* - onCreateViewHolder
* - onBindViewHolder
* - getItemCount
* - getItemViewType
* <p/>
* You need to override the abstract methods introduced by this class. This class
* is not using generics as RecyclerView.Adapter make yourself sure to cast right.
* <p/>
* TOTALLY UNTESTED - USE WITH CARE - HAVE FUN :)
*/
public abstract class HeaderRecyclerViewAdapterV2 extends RecyclerView.Adapter {
private static final int TYPE_HEADER = Integer.MIN_VALUE;
private static final int TYPE_FOOTER = Integer.MIN_VALUE + 1;
private static final int TYPE_ADAPTEE_OFFSET = 2;
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_HEADER) {
return onCreateHeaderViewHolder(parent, viewType);
} else if (viewType == TYPE_FOOTER) {
return onCreateFooterViewHolder(parent, viewType);
}
return onCreateBasicItemViewHolder(parent, viewType - TYPE_ADAPTEE_OFFSET);
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (position == 0 && holder.getItemViewType() == TYPE_HEADER) {
onBindHeaderView(holder, position);
} else if (position == getBasicItemCount() && holder.getItemViewType() == TYPE_FOOTER) {
onBindFooterView(holder, position);
} else {
onBindBasicItemView(holder, position - (useHeader() ? 1 : 0));
}
}
@Override
public int getItemCount() {
int itemCount = getBasicItemCount();
if (useHeader()) {
itemCount += 1;
}
if (useFooter()) {
itemCount += 1;
}
return itemCount;
}
@Override
public int getItemViewType(int position) {
if (position == 0 && useHeader()) {
return TYPE_HEADER;
}
if (position == getBasicItemCount() && useFooter()) {
return TYPE_FOOTER;
}
if (getBasicItemType(position) >= Integer.MAX_VALUE - TYPE_ADAPTEE_OFFSET) {
new IllegalStateException("HeaderRecyclerViewAdapter offsets your BasicItemType by " + TYPE_ADAPTEE_OFFSET + ".");
}
return getBasicItemType(position) + TYPE_ADAPTEE_OFFSET;
}
public abstract boolean useHeader();
public abstract RecyclerView.ViewHolder onCreateHeaderViewHolder(ViewGroup parent, int viewType);
public abstract void onBindHeaderView(RecyclerView.ViewHolder holder, int position);
public abstract boolean useFooter();
public abstract RecyclerView.ViewHolder onCreateFooterViewHolder(ViewGroup parent, int viewType);
public abstract void onBindFooterView(RecyclerView.ViewHolder holder, int position);
public abstract RecyclerView.ViewHolder onCreateBasicItemViewHolder(ViewGroup parent, int viewType);
public abstract void onBindBasicItemView(RecyclerView.ViewHolder holder, int position);
public abstract int getBasicItemCount();
/**
* make sure you don't use [Integer.MAX_VALUE-1, Integer.MAX_VALUE] as BasicItemViewType
*
* @param position
* @return
*/
public abstract int getBasicItemType(int position);
}
Comentários e garfos apreciados. Vou usar HeaderRecyclerViewAdapterV2por mim mesmo e evoluir, testar e publicar as mudanças no futuro.
EDIT : @OvidiuLatcu Sim, tive alguns problemas. Na verdade, parei de compensar implicitamente o cabeçalho position - (useHeader() ? 1 : 0)e, em vez disso, criei um método público int offsetPosition(int position)para ele. Como se você definir um OnItemTouchListenerna Reciclerview, poderá interceptar o toque, obter as coordenadas x, y do toque, encontrar a visão filho correspondente e, em seguida, ligar recyclerView.getChildPosition(...)e sempre obterá a posição não compensada no adaptador! Isso é uma falha no código do RecyclerView, não vejo um método fácil de superar isso. É por isso que agora compenso as posições explícitas quando preciso pelo meu próprio código.
