![](/img/trans.png)
[英]How to access the data source of a RecyclerView adapter's ViewHolder?
[英]Recyclerview is not displaying data when using generic adapter & viewholder
在我的Android項目中,我創建了通用RecyclerView的Adapter類和Viewholder類,如下所示,
適配器類
public class BaseRecyclerViewAdapter extends RecyclerView.Adapter<BaseViewHolder> {
private ItemClickListener itemClickListener;
private List<? extends Object> objectArrayList;
private int layout;
private BaseViewHolder baseViewHolder;
public BaseRecyclerViewAdapter(int layout, ItemClickListener itemClickListener, List<? extends Object> objectArrayList) {
this.layout = layout;
this.itemClickListener = itemClickListener;
this.objectArrayList = objectArrayList;
}
public BaseRecyclerViewAdapter(BaseViewHolder baseViewHolder, int layout,
ItemClickListener itemClickListener, List<? extends Object> objectArrayList) {
this.baseViewHolder = baseViewHolder;
this.layout = layout;
this.itemClickListener = itemClickListener;
this.objectArrayList = objectArrayList;
}
@NonNull
@Override
public BaseViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(layout, parent, false);
return new BaseViewHolder(itemView, itemClickListener);
}
@Override
public void onBindViewHolder(@NonNull BaseViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return objectArrayList.size();
}
}
ViewHolder類
public class BaseViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
private CardView cardView;
private AppCompatImageView imgEdit;
private AppCompatImageView imgDelete;
private ItemClickListener itemClickListener;
public BaseViewHolder(View itemView, ItemClickListener itemClickListener) {
super(itemView);
cardView = itemView.findViewById(R.id.cardView);
imgEdit = itemView.findViewById(R.id.imgEdit);
imgDelete = itemView.findViewById(R.id.imgDelete);
imgDelete.setOnClickListener(this);
cardView.setOnClickListener(this);
cardView.setOnLongClickListener(this);
this.itemClickListener = itemClickListener;
}
@Override
public void onClick(View view) {
if (view.getId() == cardView.getId()) {
itemClickListener.onClick(view, getLayoutPosition(), ConstantCodes.ACTION_CLICK);
} else if (view.getId() == imgDelete.getId()) {
itemClickListener.onClick(view, getLayoutPosition(), ConstantCodes.ACTION_DELETE);
} else if (view.getId() == imgEdit.getId()) {
itemClickListener.onClick(view, getLayoutPosition(), ConstantCodes.ACTION_EDIT);
}
}
@Override
public boolean onLongClick(View view) {
itemClickListener.onLongClick(view, getLayoutPosition());
return false;
}
}
這是我在活動類中實現上述適配器和視圖持有器的方式
private class DispatchViewHolder extends BaseViewHolder {
AppCompatTextView txtInvoiceNo;
AppCompatTextView txtVehicleNo;
AppCompatTextView txtPartyName;
AppCompatTextView txtNoOfBags;
AppCompatTextView txtMaterialType;
AppCompatTextView txtWeight;
DispatchViewHolder(View itemView, ItemClickListener itemClickListener) {
super(itemView, itemClickListener);
}
}
private class DispatchMaterialAdapter extends BaseRecyclerViewAdapter {
ItemClickListener itemClickListener;
List<? extends Object> objectArrayList;
DispatchMaterialAdapter(ItemClickListener itemClickListener, List<? extends Object> objectArrayList) {
super(R.layout.dispatch_material_row, itemClickListener, objectArrayList);
this.itemClickListener = itemClickListener;
this.objectArrayList = objectArrayList;
}
@NonNull
@Override
public DispatchViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.dispatch_material_row, parent, false);
return new DispatchViewHolder(itemView, itemClickListener);
}
@Override
public void onBindViewHolder(@NonNull BaseViewHolder holder, int position) {
try {
DispatchViewHolder dispatchViewHolder = (DispatchViewHolder) holder;
DispatchMaterialMd dispatchMaterialMd = (DispatchMaterialMd) objectArrayList.get(position);
dispatchViewHolder.txtInvoiceNo.setText(dispatchMaterialMd.getInvoiceNo());
dispatchViewHolder.txtVehicleNo.setText(dispatchMaterialMd.getVehicleNo());
dispatchViewHolder.txtPartyName.setText(dispatchMaterialMd.getPartyName());
dispatchViewHolder.txtNoOfBags.setText(dispatchMaterialMd.getNoOfBags());
dispatchViewHolder.txtMaterialType.setText(dispatchMaterialMd.getMaterialType());
dispatchViewHolder.txtWeight.setText(dispatchMaterialMd.getWeight());
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public int getItemCount() {
return dispatchMaterialMds.size();
}
}
我的objectArrayList列表中有數據。 我可以在控制台中打印它,但是recyclerview中什么都沒有。 在recyclerview中,它僅顯示空的Textview。
按照以下方式,實施recyclerview,
layoutManager = new LinearLayoutManager(this);
dispatchMaterialAdapter =
new DispatchMaterialAdapter(itemClickListener, dispatchMaterialMds);
recycleListDetail.setLayoutManager(layoutManager);
recycleListDetail.setAdapter(dispatchMaterialAdapter);
dispatchMaterialMds是模型類的數組列表,該列表由數據庫的數據填充。
您能不能幫我,為什么我的數據沒有顯示?
您使執行充氣的BaseViewHolder然后在DispatchViewHolder中重做它,不確定是否能解決問題,但是重復了代碼。
private class DispatchViewHolder extends BaseViewHolder {
AppCompatTextView txtInvoiceNo;
AppCompatTextView txtVehicleNo;
AppCompatTextView txtPartyName;
AppCompatTextView txtNoOfBags;
AppCompatTextView txtMaterialType;
AppCompatTextView txtWeight;
DispatchViewHolder(View itemView, ItemClickListener itemClickListener) {
super(itemView, itemClickListener);
}
}
private class DispatchMaterialAdapter extends BaseRecyclerViewAdapter {
ItemClickListener itemClickListener;
List<? extends Object> objectArrayList;
DispatchMaterialAdapter(ItemClickListener itemClickListener, List<? extends Object> objectArrayList) {
super(R.layout.dispatch_material_row, itemClickListener, objectArrayList);
this.itemClickListener = itemClickListener;
this.objectArrayList = objectArrayList;
}
@Override
public DispatchViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.dispatch_material_row, parent, false);
return new DispatchViewHolder(itemView, itemClickListener);
}
@Override
public void onBindViewHolder(@NonNull BaseViewHolder holder, int position) {
try {
DispatchViewHolder dispatchViewHolder = (DispatchViewHolder) holder;
DispatchMaterialMd dispatchMaterialMd = (DispatchMaterialMd) objectArrayList.get(position);
dispatchViewHolder.txtInvoiceNo.setText(dispatchMaterialMd.getInvoiceNo());
dispatchViewHolder.txtVehicleNo.setText(dispatchMaterialMd.getVehicleNo());
dispatchViewHolder.txtPartyName.setText(dispatchMaterialMd.getPartyName());
dispatchViewHolder.txtNoOfBags.setText(dispatchMaterialMd.getNoOfBags());
dispatchViewHolder.txtMaterialType.setText(dispatchMaterialMd.getMaterialType());
dispatchViewHolder.txtWeight.setText(dispatchMaterialMd.getWeight());
} catch (Exception e) {
e.printStackTrace();
}
}
}
在DispatchViewHolder中:
AppCompatTextView txtInvoiceNo;
AppCompatTextView txtVehicleNo;
AppCompatTextView txtPartyName;
AppCompatTextView txtNoOfBags;
AppCompatTextView txtMaterialType;
AppCompatTextView txtWeight;
DispatchViewHolder(View itemView, ItemClickListener itemClickListener) {
super(itemView, itemClickListener);
//Initiliazation of new view?
}
如下更改設置適配器代碼。
recycleListDetail.setLayoutManager(new LinearLayoutManager(this));
dispatchMaterialAdapter =
new DispatchMaterialAdapter(itemClickListener, dispatchMaterialMds);
recycleListDetail.setLayoutManager(layoutManager);
recycleListDetail.setAdapter(dispatchMaterialAdapter);
dispatchMaterialAdapter.notifyDataSetChanged();
並在綁定視圖中檢查適配器,以獲取arraylist值,並在獲取和傳遞給適配器時檢查arraylist類型是否相同。
上面的討論中,我為回收者視圖進行了演示,並使用簡單的字符串數組進行了喚醒。
公共類RecyclerViewAdpater擴展了RecyclerView.Adapter {List mStringList = new ArrayList <>(); //聽說您可以傳遞任何pojo類對象。 上下文mContext;
public RecyclerViewAdpater(List<String> mStringList, Context mContext) {
this.mStringList = mStringList;
this.mContext = mContext;
}
@Override
public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_main,parent,false);
return new ItemViewHolder(view);
}
@Override
public void onBindViewHolder(ItemViewHolder holder, int position) {
String data=mStringList.get(position); // if you pass object of class then create that class object.
holder.textView.setText(data);
}
@Override
public int getItemCount() {
return mStringList.size();
}
public class ItemViewHolder extends RecyclerView.ViewHolder {
TextView textView;
public ItemViewHolder(View itemView) {
super(itemView);
textView=itemView.findViewById(R.id.timeData);
}
}
}
然后實現如下活動,將以下代碼放入onCreate視圖方法中...
recyclerViewAdpater=new RecyclerViewAdpater(mStingList,this);
mRvData.setLayoutManager(new LinearLayoutManager(this));
mRvData.setAdapter(recyclerViewAdpater);
chatAdapter.notifyDataSetChanged();
請嘗試這個
@Override
public int getItemCount() {
return objectArrayList.size();
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.