Question

我有一个recyclerview。我想在点击项目时更改项目的背景。使用我的代码更改了单击的项目，但滚动时，还有一些项目的背景也发生了变化，当向后滚动时，初始项目的背景更改回默认值。

这是我的适配器：

公共类MyCustomAdapter扩展了RecyclerView.Adapter {

private Context context;

private ArrayList<Information> data;

private LayoutInflater inflater;

private int previousPosition = 0;

private Resources resources;

private Drawable drawable;

public MyCustomAdapter(Context context, ArrayList<Information> data) {

    this.context = context;
    this.data = data;
    inflater = LayoutInflater.from(context);
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int position) {

    View view = inflater.inflate(R.layout.list_item_row, parent, false);

    MyViewHolder holder = new MyViewHolder(view);

    return holder;
}

@Override
public void onBindViewHolder(final MyViewHolder myViewHolder, final int position) {

    myViewHolder.textView1.setText(data.get(position).title);
    //myViewHolder.imageView.setImageResource(data.get(position).imageId);

    if(position > previousPosition){ // We are scrolling DOWN

        AnimationUtil.animate(myViewHolder, true);

    }else{ // We are scrolling UP

        AnimationUtil.animate(myViewHolder, false);
    }

    previousPosition = position;

    final int currentPosition = position;
    final Information infoData = data.get(position);


    myViewHolder.cardView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Toast.makeText(context, "Onlick Called at position "+position, Toast.LENGTH_LONG).show();
            //myViewHolder.imageView.setImageResource(data.get(position).imageId);
            resources = context.getResources();
            drawable = resources.getDrawable(data.get(position).imageId);
            myViewHolder.relativeLayout.setBackground(drawable);
        }
    });

}

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

class MyViewHolder extends RecyclerView.ViewHolder{

    TextView textView1;
    TextView textView2;
    CardView cardView;
    ImageView imageView;
    RelativeLayout relativeLayout;


    public MyViewHolder(View itemView) {
        super(itemView);
        textView1 = (TextView) itemView.findViewById(R.id.card_front_text1);
        textView2 = (TextView) itemView.findViewById(R.id.card_front_text2);
        imageView = (ImageView) itemView.findViewById(R.id.card_front_imageview);
        relativeLayout = (RelativeLayout) itemView.findViewById(R.id.card_front_relativelayout);
        cardView = (CardView)   itemView.findViewById(R.id.cardView);
    }
}

}

XML：

父级布局是Cardview，并且有一个相对布局子级。

Answer 1

因为物料视图由RecyclerView重复使用。在onBindViewHolder方法中，必须将项目视图设置为正确的状态。

Answer 2

RecyclerView将重复使用视图来填充数据。您应该保存单击视图的位置。在OnClickListener保存位置：

myViewHolder.cardView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        clickedPosition = position;
        ......
    }
});

在onBindViewHolder中添加以下内容：

if (position == clickedPosition) {
    resources = context.getResources();
    drawable = resources.getDrawable(data.get(position).imageId);
    myViewHolder.relativeLayout.setBackground(drawable);
} else {
    myViewHolder.relativeLayout.setBackground(/* default background*/);
}

RecyclerView - 滚动时复制，当项目触摸时，它会更改项目的背景

2 个答案: