How to get the List size() from adapter and update Activity UI from recycler Adapter itself?

问题

I have a delete button in my adapter call and when i press the delete button i want to

1. remove the value from list and,

2. Update the size of the list in the main activity

and . Have tried using Interface where i referred here but it's not working and i am so confused.

So can any one provide me an best way

My Adapter Code:

@Override
public void onBindViewHolder(final AddLineItem_Adapter.ViewHolder holder, final int position) {
    final AddLineItem_ListView addLineItem_listView = addLineItem_listViews.get(position);

    holder.tv_OrderID.setText(addLineItem_listView.getItemID());
    holder.tv_ProductName.setText(addLineItem_listView.getProductName());
    holder.tv_Quantity.setText(addLineItem_listView.getQuantity());
    holder.tv_UnitPrice.setText(addLineItem_listView.getUnitPrice());
    holder.tv_TotalAmount.setText(addLineItem_listView.getTotalAmount());

    holder.btn_Delete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            addLineItem_listViews.remove(position);
            notifyDataSetChanged();
        }
    });
}

I want to update the addLineItem_listView size on the main activity in TextView.

回答1:

Create the interface..
Pass it to the adapter..
Call interface function after deleting (providing the size of list)

Create interface

public interface ShowDeleted {

void showDeleted(int size);

}

Initialize the interface anonymously in the activity like this

ShowDeleted showDeleted = new ShowDeleted() {
    @Override
    public void showDeleted(int size) {
         // show the changed list size or update UI
    }
};

Pass the interface to the recyclerAdapter

YourAdapter youradpter = new YourAdpater(context,list,showDeleted );

Initialize the constructor of recyclerAdapter like this:-

   public YourAdapter(Context context, YourList yourList, ShowDeleted 
                                                           showDeleted)
     {
            }

holder.onClick do this

holder.btn_Delete.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        addLineItem_listViews.remove(position);
        notifyDataSetChanged();
        this.showDeleted.showDeleted(addLineItem_listViews.size());
    }
});

回答2:

try to use view.setTag(position)

@Override
public void onBindViewHolder(final AddLineItem_Adapter.ViewHolder holder, final int position) {
    final AddLineItem_ListView addLineItem_listView = addLineItem_listViews.get(position);

    holder.tv_OrderID.setText(addLineItem_listView.getItemID());
    holder.tv_ProductName.setText(addLineItem_listView.getProductName());
    holder.tv_Quantity.setText(addLineItem_listView.getQuantity());
    holder.tv_UnitPrice.setText(addLineItem_listView.getUnitPrice());
    holder.tv_TotalAmount.setText(addLineItem_listView.getTotalAmount());
    holder.btn_Delete.setTag(position)
    holder.btn_Delete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            addLineItem_listViews.remove((Integer)v.getTag());
            notifyDataSetChanged();
        }
    });
}

Good Luck!

回答3:

use this function

 public void removeAt(int position) {
    list.remove(position);
    notifyItemRemoved(position);
    notifyItemRangeChanged(position, list.size());
}

来源：https://stackoverflow.com/questions/48904077/how-to-get-the-list-size-from-adapter-and-update-activity-ui-from-recycler-ada

标签

android

android-adapter