Question

我需要的是当有人点击列表中的项目时在Recyclerview适配器类中实现我的自定义侦听器

我确实创建了一个接口类

public interface Selected_Item_Listener {
void onButtonClicked(boolean optional,String product_name,String ID);
}

在主要活动中，我使用了

Selected_Item_Listener selected_item_listener;
calss whatever{
init(savedInstanceState);

selected_item_listener = new Selected_Item_Listener() {
            @Override
            public void onButtonClicked(boolean optional, String 
     product_name, String ID) {
 };

public void init(Bundle savedInstanceState) {
  itemAdapter = new ItemAdapter(item_list, 
   getContext(),selected_item_listener);
    LinearLayoutManager horizontalLayoutManager = new 
  LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false);
    service_items.setLayoutManager(horizontalLayoutManager);
    service_items.setAdapter(itemAdapter);
    populateList();
  }
  private void populatList(){

    item_list.add(new 
    serive_items_list_item(R.drawable.gg,"gg",""));
    item_list.add(new 
    serive_items_list_item(R.drawable.gg,"gg",""));
    item_list.add(new serive_items_list_item(R.drawable.gg,"gg
    gg",""));
    itemAdapter.notifyDataSetChanged();
}
}

在我的适配器类中，我添加以下代码

public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemViewHolder> {

Context context;
List<serive_items_list_item> horizontalList;
Selected_Item_Listener selected_item_listener;

public ItemAdapter(List<serive_items_list_item> horizontalList, Context context,Selected_Item_Listener selected_item_listener) {
    this.horizontalList = horizontalList;
    this.selected_item_listener = selected_item_listener;
    this.context = context;
}


@Override
public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    //inflate the layout file
    View itemProductView = LayoutInflater.from(parent.getContext()).inflate(R.layout.service_item_items, parent, false);
    ItemViewHolder gvh = new ItemViewHolder(itemProductView);
    return gvh;
}

@Override
public void onBindViewHolder(ItemViewHolder holder, final int position) {
    if (horizontalList.size() == 2){
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        params.setMargins(Main.screenWidth/8, 0, Main.screenWidth/9, 0);
     holder.lay.setLayoutParams(params);
    }else {

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.WRAP_CONTENT
        );
        params.setMargins(Main.screenWidth/28, 0, Main.screenWidth/20, 0);
        holder.lay.setLayoutParams(params);


    }
    holder.imageView.setImageResource(horizontalList.get(position).getImageResource());
    holder.txtview.setText(horizontalList.get(position).getText());
    holder.imageView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String productName = horizontalList.get(position).getText().toString();
            if (selected_item_listener != null){
                selected_item_listener.onButtonClicked(true, productName, "");
        }

        }
    });
}

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

public class ItemViewHolder extends RecyclerView.ViewHolder {
    ImageView imageView;
    TextView txtview;
    LinearLayout lay;
    public ItemViewHolder(View view) {
        super(view);
        imageView=(ImageView) view.findViewById(R.id.imageview_item);
        txtview=(TextView) view.findViewById(R.id.textview_title_item);
        lay = (LinearLayout)view.findViewById(R.id.linear_view);
    }
  }
 }

由于某种原因，它会在此行抛出空指针异常

selected_item_listener.onButtonClicked(true, productName, "");

selected_item_listener是null，我想知道我错过了什么？，我使用相同的类和代码与另一个扩展Dialogs并正常工作的类

Answer 1

嗯，这似乎是我在初始化之前尝试将我的听众发送到我的适配器的问题

我试图把init（savedInstanceState）;在selected_item_listener = new之后Selected_Item_Listener（）{};它现在正在工作

在Recyclerview适配器类

1 个答案: