我试图在我的适配器中添加标头但我不能bindViewHolder . 任何人都可以帮我解决这些问题吗？这是我的适配器代码：
public class AdapterItem extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final int VIEW_HEADER=0;
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 2;
private ArrayList<Item> itemList;
private OnLoadMoreListener onLoadMoreListener;
private LinearLayoutManager mLinearLayoutManager;
private boolean isMoreLoading = false;
private int visibleThreshold = 1;
int firstVisibleItem, visibleItemCount, totalItemCount;
public interface OnLoadMoreListener{
void onLoadMore();
}
public AdapterItem(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener=onLoadMoreListener;
itemList =new ArrayList<>();
}
public void setLinearLayoutManager(LinearLayoutManager linearLayoutManager){
this.mLinearLayoutManager=linearLayoutManager;
}
public void setRecyclerView(RecyclerView mView){
mView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = recyclerView.getChildCount();
totalItemCount = mLinearLayoutManager.getItemCount();
firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition();
if (!isMoreLoading && (totalItemCount - visibleItemCount)<= (firstVisibleItem + visibleThreshold)) {
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
isMoreLoading = true;
}
}
});
}
@Override
public int getItemViewType(int position) {
if(itemList.get(position) != null && isPositionHeader(position)){
return VIEW_HEADER;
}else if(itemList.get(position) != null) {
return VIEW_ITEM;
}else{
return VIEW_PROG;
}
}
private boolean isPositionHeader (int position) {
return position == 0;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
if (viewType == VIEW_HEADER) {
return new StudentViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.header, parent, false));
}else
if (viewType == VIEW_ITEM) {
return new StudentViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_text, parent, false));
}else {
return new ProgressViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_progress, parent, false));
}
}
public void addAll(List<Item> lst){
itemList.clear();
itemList.addAll(lst);
notifyDataSetChanged();
}
public void addItemMore(List<Item> lst){
itemList.addAll(lst);
notifyItemRangeChanged(0,itemList.size());
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof StudentViewHolder) {
Item singleItem = (Item) itemList.get(position);
((StudentViewHolder) holder).tvItem.setText(singleItem.getItem());
}
}
public void setMoreLoading(boolean isMoreLoading) {
this.isMoreLoading=isMoreLoading;
}
@Override
public int getItemCount() {
return itemList.size();
}
public void setProgressMore(final boolean isProgress) {
if (isProgress) {
new Handler().post(new Runnable() {
@Override
public void run() {
itemList.add(null);
notifyItemInserted(itemList.size() - 1);
}
});
} else {
itemList.remove(itemList.size() - 1);
notifyItemRemoved(itemList.size());
}
}
static class StudentViewHolder extends RecyclerView.ViewHolder {
public TextView tvItem;
public StudentViewHolder(View v) {
super(v);
tvItem = (TextView) v.findViewById(R.id.tvItem);
}
}
static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar pBar;
public ProgressViewHolder(View v) {
super(v);
pBar = (ProgressBar) v.findViewById(R.id.pBar);
}
}
}
这是我的错误日志
11-10 14：02：12.115 2151-2151 / com.esantiago.pagination E / AndroidRuntime：FATAL EXCEPTION：main进程：com.esantiago.pagination，PID：2151 com.esantiago.pagination.adapter中的java.lang.NullPointerException .AdapterItem $ override.onBindViewHolder（AdapterItem.java:105）at com.esantiago.pagination.adapter.AdapterItem $ override.access $ dispatch（AdapterItem.java）at com.esantiago.pagination.adapter.AdapterItem.onBindViewHolder（AdapterItem.java） ：0）在android.support.v7.widget.RecyclerView $ Adapter.onBindViewHolder（RecyclerView.java:5465）android.support的android.support.v7.widget.RecyclerView $ Adapter.bindViewHolder（RecyclerView.java:5498） . v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:4735）在android.support.v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:4611）的android.support.v7.widget.LinearLayoutManager $ LayoutState . next（LinearLayoutManager.java:1988）在android.support.v7.widget.LinearLayoutManager.layoutChunk（LinearLayoutManager.java:1384）在android.support.v7.widget.LilloutManager.fill（LinearLayoutManager.java:1347）android.support.v7.widget.LinearLayoutManager.onLayoutChildren（LinearLayoutManager.java:584）android.support.v7.widget.RecyclerView.dispatchLayoutStep1上的android.support.v7.widget.LinearLayoutManager.fill（LinearLayoutManager.java:1347） （RecyclerView.java:2977）位于android.sview的android.support.v7.widget.RecyclerView.dispatchLayout（RecyclerView.java:2901）android.support.v7.widget.RecyclerView.onLayout（RecyclerView.java:3277） . 在android.view.View.View的android.sview.v4上安装了android.view.View（ . View.java：4631）的android.view视频（View.java:14817），以及android.view.View上的android.support.v4.widget.SwipeRefreshLayout.onLayout（SwipeRefreshLayout.java:596） .layout（View.java:14817）位于Android.widget.LinearLayout.setoutVertical（LinearLayout . ）的android.widget.LinearLayout.setChildFrame（LinearLayout.java:1671）上的android.view.ViewGroup.layout（ViewGroup.java:4631） . java：1525）在android.view.Layout.onLayout（LinearLayout.java:1434）的android.view.View.layout（View.java:14817）android.view.ViewGroup.layout（ViewGroup.j） ava：4631）android.widget.FrameLayout.layoutChildren（FrameLayout.java：453）在android.view.View.layout（View.java:14817）的android.widget.FrameLayout.onLayout（FrameLayout.java:388） android.view.View.layout（ViewGroup.java:4631）在android.sview.v.widget.ActionBarOverlayLayout.onLayout（ActionBarOverlayLayout.java:435）在android.view.View.layout（View.java:14817）在android .view.ViewGroup.layout（ViewGroup.java:4631）位于android.view.View.View.View.View的Android.widget.FrameLayout.onLayout（FrameLayout.java:388）的android.widget.FrameLayout.layoutChildren（FrameLayout.java:453） . 在Android.widget.LinearLayout.setoutVertical（LinearLayout.java）的android.widget.LinearLayout.setChildFrame（LinearLayout.java:1671）的android.view.ViewGroup.layout（ViewGroup.java:4631）上的布局（View.java:14817） ：1525）在android.view.Layout.onLayout（LinearLayout.java：1434）的android.view.View.layout（View.java:14817）在android.view.ViewGroup.layout（ViewGroup.java:4631）在android .widget.FrameLayout.layoutChild ren（FrameLayout.java:453）位于android.view.View.Loutout（ViewLayout.java:388）的android.view.View.layout（View.java:14817）android.view.ViewGroup.layout（ViewGroup.java） ：4631）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1740）android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:996）android.view.ViewRootImpl.performLayout（ViewRootImpl.java:1983） .view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:5600）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:761）的android.view.Choreographer.doCallbacks（Choreographer.java:574） . 在android.view.Handler的android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:747）的android.O. android.app.Looper.loop（Looper.java：136）中的.dispatchMessage（Handler.java:95）位于android.app.ActivityThread.main（ActivityThread.java:5001）的java.lang.reflect.Method.invokeNati在c的java.lang.reflect.Method.invoke（Method.java:515）的ve（Native Method）