java - 单击项目后，如何从 RecyclerView 的适配器内的 drawable 更改 imageView 的图像？

Question

1. 我从 SERVER 获取数据以填充 RECYCLER View
2. 我在每个 recyclerview 行中都有一个 imageview

3. 当我点击那个 imageview 时，我想将我的 drawable 加载到 imageview 中

   holder.imageView.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View view) {
   
   
           Drawable placeholder = holder.imageView.getContext().getResources().getDrawable(R.drawable.app);
           holder.imageView.setImageDrawable(placeholder);
   
       }
   });
   

上面是我尝试过的，但它说“holder”需要被声明为最终的，但实际上，我什至没有以我可以写成“final holder”之类的方式提到它。

我的适配器代码:

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


private Context mCtx;
private List<Product> productList;

public ProductsAdapter(Context mCtx, List<Product> productList) {
    this.mCtx = mCtx;
    this.productList = productList;
}

@Override
public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    LayoutInflater inflater = LayoutInflater.from(mCtx);
    View view = inflater.inflate(R.layout.product_list, null);
    return new ProductViewHolder(view);
}

@Override
public void onBindViewHolder(ProductViewHolder holder, int position) {
    final Product product = productList.get(position);

    //loading the image
    Glide.with(mCtx)
            .load(product.getImage())
            .into(holder.imageView);

    holder.textViewTitle.setText(product.getTitle());
    holder.textViewShortDesc.setText(product.getShortdesc());
    holder.textViewRating.setText(String.valueOf(product.getRating()));
    holder.textViewPrice.setText(String.valueOf(product.getPrice()));


    holder.imageView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {


            Drawable placeholder = holder.imageView.getContext().getResources().getDrawable(R.drawable.app);
            holder.imageView.setImageDrawable(placeholder);

        }
    });



        }

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

class ProductViewHolder extends RecyclerView.ViewHolder {

    TextView textViewTitle, textViewShortDesc, textViewRating, textViewPrice;
    ImageView imageView;

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

        textViewTitle = itemView.findViewById(R.id.textViewTitle);
        textViewShortDesc = itemView.findViewById(R.id.textViewShortDesc);
        textViewRating = itemView.findViewById(R.id.textViewRating);
        textViewPrice = itemView.findViewById(R.id.textViewPrice);
        imageView = itemView.findViewById(R.id.imageView);
    }
}
}

Answer 1

您可以在方法头中声明持有者final

public void onBindViewHolder(final ProductViewHolder holder, int position) {
    Your code here
}