使用RecyclerView适配器在运行时更改布局屏幕 [英] Change layout screen in runtime with RecyclerView adapter
问题描述
我有两个布局文件如下所示。
I have two layout files shown below.
如果列表中有数据,那么我会显示这种布局。
If data is present in list then I show this layout.
当列表为空时,我会显示此布局。
and when list is empty then I show this layout.
现在我想在运行时更改布局。当用户从列表中删除最后一项时,我想将布局更改为第二张图像中显示的清空购物车布局。
Now I wanted to change layout at runtime. When ever user deletes last item from list I wanted to change layout to 'Empty cart layout' shown in second image.
在中getItemCount()
RecyclerView适配器的方法如果列表为空或为null然后我返回计数为 1
否则我返回 list.size()
In getItemCount()
method of RecyclerView adapter if list is empty or null then I return count as 1
otherwise I return list.size()
这是我的适配器代码。
public class CheckOutAdapter extends RecyclerView.Adapter<CheckOutAdapter.ViewHolder> {
public ArrayList<Design> designList;
private Context context;
private LayoutInflater layoutInflater;
public CheckOutAdapter(Context context, ArrayList<Design> designList) {
this.designList = designList;
this.context = context;
this.layoutInflater = LayoutInflater.from(context);
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if(designList.isEmpty() || designList == null || designList.size() == 0) {
View view = layoutInflater.inflate(R.layout.empty_cart, parent, false);
return new ViewHolder(view);
} else {
View view = layoutInflater.inflate(R.layout.checkout_single_design, parent, false);
return new ViewHolder(view);
}
}
@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
final Design design = designList.get(position);
holder.tvQuality.setText(design.qualityName);
holder.tvDesign.setText(design.designName);
holder.tvShade.setText(design.name);
holder.tvAmount.setText("₹ " + design.amount);
Picasso.with(context).load(design.image).into(holder.ivDesign);
if (design.pcs != 0) {
holder.btPcsCount.setText(Integer.toString(design.pcs));
}
holder.ivDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
openDialog(design);
}
});
//other ClickListeners.
}
@Override
public int getItemCount() {
if (designList == null || designList.isEmpty() || designList.size() == 0) {
return 1;
} else {
return designList.size();
}
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public LinearLayout llPer;
public Button btPlus, btMinus, btPcsCount, btAddCart;
public ImageView ivDesign, ivDelete;
public TextView tvDesign, tvQuality, tvShade, tvAmount, tvDiscAmt, tvDisPer;
public ViewHolder(View itemView) {
super(itemView);
llPer = (LinearLayout) itemView.findViewById(R.id.llPer);
btPlus = (Button) itemView.findViewById(R.id.btPlus);
//other findViewByIds
}
}
public void openDialog(final Design design) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Confirm");
builder.setMessage("Remove item from cart?");
builder.setPositiveButton("YES", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
designList.remove(design);
notifyDataSetChanged();
saveSharedPref(context, "cart", new Gson().toJson(designList));
Toast.makeText(context, "deleted", Toast.LENGTH_SHORT).show();
dialog.dismiss();
}
});
builder.setNegativeButton("NO", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
AlertDialog alert = builder.create();
alert.show();
}
}
我在附近得到NullPointerException onBindViewHolder
。我不知道它为什么会崩溃。请给出建议。
I am getting NullPointerException near onBindViewHolder
. I don't know why it getting crashed. please give suggestions.
推荐答案
你可以覆盖 getItemViewType()
:
You can do that overriding getItemViewType()
:
@Override
public int getItemViewType(int position) {
if (designList.size() == 0) return R.layout.empty;
else return R.layout.normal_layout;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(viewType, parent, false);
ViewHolder viewHolder = null;
if (viewType == R.layout.empty) {
viewHolder = new EmptyViewHolder(view);
} else {
viewHolder = new NormalViewHolder(view);
}
return viewholder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceOf EmptyViewHolder){
// this is empty item, update view appropriately if needed
} else {
// this is normal item, update view appropriately if needed
}
}
现在,当数据集发生变化且适配器中只有1项时,您将获得所需的布局。
Now, when dataset changes and there's only 1 item in your adapter, you'd get the desired layout shown.
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