Question

我制作了一个适配器，以显示我们必须选择它们的许多城市。但是，当我向下滚动并再次返回时，所选项目将再次被取消选择。

我尝试将sethasStableIds设置为true，但这也不起作用

public class CitiesAdapter extends RecyclerView.Adapter<CitiesAdapter.ViewHolder> {

private static final String TAG = "CitiesViewAdapter";

private List<Cities> citiesModelList;
private Context mContext;
private OnClickListner mOnNoteListner;

public CitiesAdapter(List<Cities> citiesModelList, Context mContext , OnClickListner mOnNoteListner) {
    this.citiesModelList = citiesModelList;
    this.mContext = mContext;
    this.mOnNoteListner = mOnNoteListner;
    setHasStableIds(true);
}

@NonNull
@Override
public CitiesAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cities_listitems, viewGroup , false);
    CitiesAdapter.ViewHolder holder = new CitiesAdapter.ViewHolder(view , mOnNoteListner , this);
    return holder;
}

@Override
public void onBindViewHolder(@NonNull CitiesAdapter.ViewHolder viewHolder, int i) {
    Log.d(TAG , "onBindViewHolder: called.");

    Cities citiesmodels = citiesModelList.get(i);
    viewHolder.tvCitiesName.setText(citiesmodels.getName());
}

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

@Override
public long getItemId(int position) {
    return position;
}

@Override
public int getItemViewType(int position)
{
    return position;
}

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

    TextView tvCitiesName;


    OnClickListner onClickListner;
    private CitiesAdapter citiesAdapter;

    public ViewHolder(@NonNull View itemView , OnClickListner onClickListner , CitiesAdapter citiesAdapter) {
        super(itemView);
        tvCitiesName = itemView.findViewById(R.id.tvCitiesName);
        this.onClickListner = onClickListner;
        itemView.setOnClickListener(this);
        this.citiesAdapter = citiesAdapter;
    }

    @Override
    public void onClick(View v) {
        onClickListner.onItemClick(getAdapterPosition(),citiesAdapter.getItem(getAdapterPosition()));
    }
}

public Cities getItem(int i){
    return citiesModelList.get(i);
}

public interface OnClickListner{
    void onItemClick(int position , Cities cities);
}

}

我在下面粘贴了我的适配器。任何帮助将不胜感激。感谢

Answer 1

在Cities对象上，定义一个名为selected的布尔属性，并使用一种方法来确定是否通过使用诸如boolean isSelected()之类的吸气剂来选择它。然后，在适配器的onBindViewHolder方法上添加如下内容：

{
    // Code to add inside onBindViewHolder.

    if (cityModel.isSelected())
    {
         // Select the view you want to select.
    }
    else
    {
         // Deselect the view.
    }
}

始终使用if-else条件以避免错误结果。

Answer 2

发生这种情况的原因是，当我们滚动onBindViewHolder方法调用时。

//create integer list for selected city or if there is only one selected city then create variable selected city
private List<integer> SelectedcitiesModelList= new ArrayList<integer>() //in adapter class

// now assign tag to tvCitiesName in onBindViewHolder method 
 viewHolder.tvCitiesName.setTag(i); //to identify the view and i is position

//now in onclick method get textview tag and put in list or variable
SelectedcitiesModelList.add(viewHolder.tvCitiesName.getTag())

//now go to onBindViewHolder method 
for(int p;i<SelectedcitiesModelList.size();p++)
    {
        if(p==i)    
        {
            //this is your selected item
            //do what you want to   
        }   
    }

Answer 3

请使用SparseBooleanArray来维护Android Recyclerview中Checkbox的状态。您可以点击此链接Using SparseBooleanArray to store Checkbox state in RecyclerView when scrolling

在Recyclerview中滚动后，“选定的项目”被取消选择

3 个答案: