如何更改 RecyclerView 中特定项目 onClick 的背景？

Question

我试图在 RecyclerView 中创建一个选定的项目以在单击它时更改其背景，但是一旦单击 RecyclerView 中的另一个项目，该项目的背景将被更改，并且先前单击的项目将变回原始。

第二次单击时，我只能设法将项目更改回原始（白色背景）。

请问有什么帮助吗？

这是我的 RecyclerView 适配器

public class CharityListAdapter extends RecyclerView.Adapter<CharityListAdapter.CharityListViewHolder> {
    String charityData[], descriptionData[];
    int images[];
    Context context;

    public CharityListAdapter(Context ct, String charity[], String description[], int image[]) {
        context = ct;
        charityData = charity;
        descriptionData= description;
        images = image;

    }

    @NonNull
    @Override
    public CharityListViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(context);
        View view = inflater.inflate(R.layout.data_row, parent, false);
        return new CharityListViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final CharityListViewHolder holder,final int position) {


        holder.titleText.setText(charityData[position]);
        holder.descText.setText(descriptionData[position]);
        holder.charityImage.setImageResource(images[position]);

        holder.charityLayout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(holder.charityLayout.isSelected()) {
                    holder.charityLayout.setSelected(false);
                    System.out.println("Set to false");

                } else if(!holder.charityLayout.isSelected()){
                    holder.charityLayout.setSelected(true);
                    System.out.println("Set to true");
                }

                if(holder.charityLayout.isSelected()) {
                    holder.whiteBox.setBackgroundResource(R.drawable.bluebox);

                    DonateSelection.enableNextButton();
                    System.out.println("Blue Box");
                }

                if(!holder.charityLayout.isSelected()) {
                    holder.whiteBox.setBackgroundResource(R.drawable.box);

                    System.out.println("White Box");
                }
            }
        });

    }

    @Override
    public int getItemCount() {                                                        
        return images.length;
    }

    public class CharityListViewHolder extends RecyclerView.ViewHolder {
        TextView titleText, descText;
        ImageView charityImage;

        RelativeLayout whiteBox;
        RelativeLayout charityLayout;

        public CharityListViewHolder(@NonNull View itemView) {
            super(itemView);

            titleText = itemView.findViewById(R.id.titleText);
            descText = itemView.findViewById(R.id.descText);
            charityImage = itemView.findViewById(R.id.charityImage);
            whiteBox = itemView.findViewById(R.id.whiteBox);
            charityLayout = itemView.findViewById(R.id.charityLayout);


        }

    }
}

Answer 1

这是因为 RecyclerView 的工作方式。 它从您的屏幕上消失后，它会回收您的视图。 您应该使用 if/else 来维护视图的正确状态。 用以下代码替换您的 onClick 操作。

 holder.charityLayout.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if(holder.charityLayout.isSelected()) {
                        holder.charityLayout.setSelected(false);
                        System.out.println("Set to false");

                    } else {
                        holder.charityLayout.setSelected(true);
                        System.out.println("Set to true");
                    }

                    if(holder.charityLayout.isSelected()) {
                        holder.whiteBox.setBackgroundResource(R.drawable.bluebox);

                        DonateSelection.enableNextButton();
                        System.out.println("Blue Box");
                    }else{

                        holder.whiteBox.setBackgroundResource(R.drawable.box);

                        System.out.println("White Box");
                    }



                }
            });

编辑这里是原始代码。但是，我认为这应该可行。 您应该添加一个由回收器组成的检查状态数组。 默认情况下，它们都是假的。 然后，检查它 onBindViewHolder()。 单击时，将 boolean 设置为 true 并调用 notifyDatasetChanged。

public class CharityListAdapter extends RecyclerView.Adapter<CharityListAdapter.CharityListViewHolder> {
    String charityData[], descriptionData[];
    int images[]; boolean checkState[];
    Context context;

    public CharityListAdapter(Context ct, String charity[], String description[], int image[],boolean checkState[]) {
        context = ct;
        charityData = charity;
        descriptionData= description;
        images = image;
    checkState=checkState;  
    }

    @NonNull
    @Override
    public CharityListViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(context);
        View view = inflater.inflate(R.layout.data_row, parent, false);
        return new CharityListViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final CharityListViewHolder holder,final int position) {


        holder.titleText.setText(charityData[position]);
        holder.descText.setText(descriptionData[position]);
        holder.charityImage.setImageResource(images[position]);

    if(checkState[position]){
      holder.whiteBox.setBackgroundResource(R.drawable.bluebox);
          DonateSelection.enableNextButton();
    }else{
        holder.whiteBox.setBackgroundResource(R.drawable.box);
    }

        holder.charityLayout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
        if(checkState[position]){
            checkState[position]=false;
        }else{
            checkState[position]=true;
        }
                 notifyDataSetChanged();
            }
        });

    }

    @Override
    public int getItemCount() {                                                        
        return images.length;
    }

    public class CharityListViewHolder extends RecyclerView.ViewHolder {
        TextView titleText, descText;
        ImageView charityImage;

        RelativeLayout whiteBox;
        RelativeLayout charityLayout;

        public CharityListViewHolder(@NonNull View itemView) {
            super(itemView);

            titleText = itemView.findViewById(R.id.titleText);
            descText = itemView.findViewById(R.id.descText);
            charityImage = itemView.findViewById(R.id.charityImage);
            whiteBox = itemView.findViewById(R.id.whiteBox);
            charityLayout = itemView.findViewById(R.id.charityLayout);


        }

    }
}

Answer 2

与其记住您选择的布局/ViewHolder，不如记住选择的位置。 在您的适配器中添加：

private int positionSelected = -1;

-1 表示没有选择。

然后，在您的 ViewHolder 构造函数中：

        public CharityListViewHolder(@NonNull View itemView) {
            super(itemView);

            ....

            charityLayout = itemView.findViewById(R.id.charityLayout);

            charityLayour.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {                    
                    positionSelected = getAdapterPosition();
                    notifyDataSetChanged();
                }
            }); 
        }

在您的 onBindViewHolder 中，您可以相应地设置背景：

if (position == positionSelected) {
    // Set background for layout to indicate selected
} else {
    // Set background for layout to indicate unselected
}