android - 从 recyclerview 中删除所有 cardviews 然后添加新的 cardviews - 添加相同的 cardviews

Question

当用户按下 FAB 时，一个 cardview 被添加到 recyclerview。每个卡片 View 内都有一个复选框。我想这样做，以便当用户勾选特定卡片 View 中的复选框时，该特定卡片 View 将被删除。

(仅供引用，每个卡片 View 都有一个微调器和复选框以及一个 TextView 和编辑文本)

我按了 4 次 fab 以将 4 个卡片 View 添加到我的屏幕。然后我从微调器中选择了不同的东西来查看发生了什么。当我勾选复选框时，该卡片 View 会删除。我勾选了所有卡片 View 的复选框，直到我没有留下任何卡片 View 。

但是当我按下 fab 添加新的 cardview 时，我注意到 cardview 具有相同的选定微调器值并且复选框已被选中..？例如，假设我首先有一个带有“土 bean ”的卡片 View ，然后我勾选了它。现在我的屏幕上什么也没有了。然后我按 fab 添加卡片 View 。然后我看到那个 cardview 上面有“土 bean ”作为 wlel，并且勾选了复选框..如果这没有意义，请要求澄清

怎么办？

ProductAdapter.java

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {

    private Map<Integer, Integer> mSpinnerSelectedItem = new HashMap<Integer, Integer>();


//this context we will use to inflate the layout
    //Remove this..Please
    // CheckBox checkBox;

    //private Context mCtx;
    private SearchableSpinner spinner;

    //we are storing all the products in a list
    private List<Product> productList;

    private Activity create;

    public ProductAdapter(Activity activity) {
        create = activity;
    }


    //getting the context and product list with constructor
    public ProductAdapter(Activity activity, List<Product> productList) {
        // this.mCtx = mCtx;
        create = activity;
        this.productList = productList;
    }

    @Override
    public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        //inflating and returning our view holder
        LayoutInflater inflater = LayoutInflater.from(create);
        View view = inflater.inflate(R.layout.layout_products, null);
        return new ProductViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ProductViewHolder holder, final int position) {
        // //getting the product of the specified position


        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(create, R.layout.item_spinner_layout,
                Product.getSpinnerItemsList());
        spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        holder.spinner.setAdapter(spinnerArrayAdapter);

        holder.spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int mPosition, long id) {
                mSpinnerSelectedItem.put(position, mPosition);

                TextView mTextView = view.findViewById(R.id.mSpinnerText);
           /* Toast.makeText(create, "Selected Item: " + mTextView.getText().toString(), Toast.LENGTH_LONG).show();
            Log.e("***************", "Selected Item: " + mTextView.getText().toString());*/


            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });


        //binding the data with the viewholder views
        if (mSpinnerSelectedItem.containsKey(position)) {
            holder.spinner.setSelection(mSpinnerSelectedItem.get(position));
        }


        holder.getView().setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(create);


                // set title
                alertDialogBuilder.setTitle("Delete Item");

                // set dialog message
                alertDialogBuilder
                        .setMessage("Are you sure you want to delete this item?")
                        .setCancelable(false)
                        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                // if this button is clicked, close
                                // current activity


                                holder.checkBox.setChecked(false);
                                holder.spinner.setSelection(0);

                                productList.remove(position);
                                notifyItemRemoved(position);

                                Toast.makeText(create, "Item removed.", Toast.LENGTH_LONG).show();


                            }
                        })
                        .setNegativeButton("No", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                // if this button is clicked, just close
                                // the dialog box and do nothing
                                dialog.cancel();
                            }
                        });

                // create alert dialog
                AlertDialog alertDialog = alertDialogBuilder.create();

                // show it
                alertDialog.show();

            }
        });





    }


    @Override
    public int getItemCount() {
        return productList.size();
    }


    class ProductViewHolder extends RecyclerView.ViewHolder {

        SearchableSpinner spinner;
        EditText editText;
        TextView textView5;
        CheckBox checkBox;
        LinearLayout linearLayout;
        View rootView;


        public ProductViewHolder(View itemView) {
            super(itemView);

            spinner = itemView.findViewById(R.id.spinner);
            editText = itemView.findViewById(R.id.editText);
            textView5 = itemView.findViewById(R.id.textView5);
            checkBox = itemView.findViewById(R.id.checkBox);
            rootView = itemView.findViewById(R.id.linearLayout);


            checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    // makes the set disappear when checkbox is ticked.
                    if(isChecked){

                        holder.checkBox.setChecked(false);
                        holder.spinner.setSelection(0);

                        productList.remove(getAdapterPosition());
                        notifyItemRemoved(getAdapterPosition());



                        Toast.makeText(create, "Done!", Toast.LENGTH_LONG).show();
                    }

                }
            });



        }

        public View getView() {
            return rootView;
        }

    }

}

Answer 1

RecyclerView 回收 ViewHolders 以提高性能。这意味着，如果“ViewHolder A”在您的微调器中选择了“选项 C”，即使您从列表中删除该项目，它也不会被销毁。当您向列表中添加新项目时，您的 RecyclerView 可能会为该项目重用“ViewHolder A”，并且选择与您之前的项目(在删除之前)相同。

为避免这种情况，请在使用 LayoutManager 的 findViewByPosition 方法将新项目添加到列表时手动更新 UI。

例子:

// FAB button onClick method:
public void onClick(View v) {
    // Add item to RecyclerView list

    int itemPosition = myRecyclerViewAdapter.itemList.indexOf(newItem);
    ProductViewHolder vh = ((ProductViewHolder)recyclerView.getLayoutManager().findViewByPosition(itemPosition));

    // Here, set everything to the default values (unchecked checkbox, etc)
}

如果你想在你的 Adapter 中保留所有 RecyclerView 相关代码(我鼓励你这样做)，你可以在你之后将 ViewHolder UI 更新为默认值删除您的项目(而不是在添加项目时)，因此您的 ViewHolder 是新鲜的并为下一个项目做好准备。

示例(更好地使用此解决方案):

// Your positive button when deleting item onClick:
public void onClick(DialogInterface dialog, int id) {

    productList.remove(position);
    notifyItemRemoved(position);

    // Set spinner to default
    // Set checkbox to unchecked

    Toast.makeText(create, "Item removed.", Toast.LENGTH_LONG).show();
}