I have a viewholder with multiple viewtypes.
When scrolling onBindViewHolder is only called when getItemViewType changes value. This causes my list items to not be updated properly.
Is this a bug? Or I'm i doing something wrong here. This seems very strange behaviour from the new recyclerView class.
Here is my adapter:
package se.davison.smartrecycleradapter;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.util.SparseIntArray;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
/**
* Created by richard on 10/11/14.
*/
public class SectionAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final String TAG = SectionAdapter.class.getSimpleName();
private final LayoutInflater inflater;
private final int sectionLayoutId;
private SparseIntArray positionSection;
private LinkedHashMap<AdapterItem, List<AdapterItem>> items = new LinkedHashMap<AdapterItem, List<AdapterItem>>();
private List<Class<? extends AdapterItem>> itemTypes = new ArrayList<Class<? extends AdapterItem>>(20);
public SectionAdapter(Context context, int sectionLayoutId, LinkedHashMap<AdapterItem, List<AdapterItem>> items) {
this.inflater = LayoutInflater.from(context);
this.sectionLayoutId = sectionLayoutId;
this.items = items;
initList(items);
}
public SectionAdapter(Context context, int sectionLayoutId) {
this.inflater = LayoutInflater.from(context);
this.sectionLayoutId = sectionLayoutId;
this.items = new LinkedHashMap<AdapterItem, List<AdapterItem>>();
initList(items);
}
@Override
public int getItemViewType(int position) {
AdapterItem item = getItem(position);
Log.d(TAG, position + ": class " + item.getClass());
return itemTypes.indexOf(item.getClass());
}
@Override
public int getItemCount() {
int count = 0;
if (items == null) {
return 0;
}
for (AdapterItem key : items.keySet()) {
count++;
List<AdapterItem> childItems = items.get(key);
if (childItems != null) {
count += childItems.size();
}
}
return count;
}
private void initList(HashMap<AdapterItem, List<AdapterItem>> items) {
positionSection = new SparseIntArray(items.size());
int count = 0;
int sectionIndex = -1;
for (AdapterItem key : items.keySet()) {
Class headerClass = key.getClass();
if (!itemTypes.contains(headerClass)) {
itemTypes.add(headerClass);
}
List<AdapterItem> childItems = items.get(key);
sectionIndex = count;
if (childItems != null) {
for (AdapterItem item : childItems) {
Class clazz = item.getClass();
if (!itemTypes.contains(clazz)) {
itemTypes.add(clazz);
}
positionSection.put(count, sectionIndex);
count++;
}
}
count++;
}
setHasStableIds(true);
}
private AdapterItem getItem(int position) {
int totalChildCount = 0;
int separatorCount = 0;
for (AdapterItem key : items.keySet()) {
if (position == 0 || position == totalChildCount + separatorCount) {
return key;
}
separatorCount++;
List<AdapterItem> list = items.get(key);
int couldCount = countList(list);
if (position < totalChildCount + separatorCount + couldCount) {
return list.get(position - (totalChildCount + separatorCount));
}
totalChildCount += couldCount;
}
return null;
}
public void setItems(LinkedHashMap<AdapterItem, List<AdapterItem>> items) {
this.items = items;
notifyDataSetChanged();
}
public void setItemsAtHeader(int id, List<AdapterItem> items) {
AdapterItem header = null;
for (AdapterItem key : this.items.keySet()) {
if (key.headerId() == id) {
header = key;
break;
}
}
if (header == null) {
throw new IllegalArgumentException(String.format("No header with id %s is found", id));
}
setItemsAtHeader(header, items);
}
private void setItemsAtHeader(AdapterItem header, List<AdapterItem> items) {
this.items.put(header, items);
}
private int countList(List<?> list) {
return list == null ? 0 : list.size();
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
AdapterItem firstItem = getFirstItemWithClass(itemTypes.get(viewType));
return firstItem.onCreateViewHolder(inflater, viewGroup);
}
private AdapterItem getFirstItemWithClass(Class<? extends AdapterItem> clazz) {
for (AdapterItem key : items.keySet()) {
if (key.getClass() == clazz) {
return key;
}
List<AdapterItem> childItems = items.get(key);
if (childItems != null) {
for (AdapterItem item : childItems) {
if (item.getClass() == clazz) {
return item;
}
}
}
}
throw new IllegalStateException("Something is wrong, you dont have any items with that class in your list");
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
AdapterItem item = getItem(position);
Log.d(TAG, "ITEM = " + item.getClass().getSimpleName());
Log.d(TAG, "POS = " + position);
if (item instanceof OneLineAdapterItem) {
Log.d(TAG, "TEXT = " + ((OneLineAdapterItem) item).getText());
}
item.onBindViewHolder(viewHolder, position);
}
}
I've also abstracted out the items like so:
public abstract class AdapterItem<VH extends RecyclerView.ViewHolder> {
public boolean isHeader(){
return false;
}
public int headerId(){
return -1;
}
public abstract VH onCreateViewHolder(LayoutInflater inflater, ViewGroup parent);
public abstract void onBindViewHolder(VH viewHolder, int position);
}
And for sections
public class SectionAdapterItem extends AdapterItem<SectionAdapterItem.ViewHolder> {
private String text;
private boolean dividerVisible = false;
public static class ViewHolder extends RecyclerView.ViewHolder{
TextView titel;
ImageView divider;
public ViewHolder(View itemView) {
super(itemView);
titel = (TextView) itemView.findViewById(android.R.id.title);
divider = (ImageView) itemView.findViewById(android.R.id.icon);
}
}
public void setDividerVisible(boolean dividerVisible) {
this.dividerVisible = dividerVisible;
}
public boolean isDividerVisible() {
return dividerVisible;
}
@Override
public boolean isHeader() {
return true;
}
@Override
public int headerId() {
return super.headerId();
}
public SectionAdapterItem(String text) {
this.text = text;
}
@Override
public ViewHolder onCreateViewHolder(LayoutInflater inflater, ViewGroup parent) {
return new ViewHolder(inflater.inflate(R.layout.top_header, parent, false));
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {
viewHolder.titel.setText(text);
viewHolder.divider.setVisibility(dividerVisible?View.VISIBLE:View.GONE);
}
}
It works fine for the frist visible rows, but then it fails.
I've forgot to implement getItemId when using setHasStableIds(true);
Implementing that solved the issue!
When you set setHasStableIds(true) means that if we request an ID for a location, any specific item will always return the same ID regardless of its position within the list. This enables us to identify a specific item even if its position changes, which will be useful later on.
For that you need to implememt getItemId method in adapter and just return it's positions.
@Override
public long getItemId(int position) {
return position;
}
来源：https://stackoverflow.com/questions/26910206/recyclerview-onbindviewholder-only-called-when-getitemviewtype-changes