ListView 延迟从底部滚动到顶部

Question

我的列表视图有点滞后。

所以，当我向下滚动我的列表视图时，性能非常好，但是当我向上滚动时，当我发现我的行时会有延迟。

我正在使用 glide 查看图片。

我的适配器中的 text3Lines 方法在我的 textView 中设置了三行文本。我的适配器中的方法 checkClass 包含一个简单的 if 条件。

在我的 OnCreate 方法中：

display = getWindowManager().getDefaultDisplay();
size = new Point();
display.getSize(size);
width_square = (size.x)/100;
height_square = (size.x)/100;

list = new ListView(this);
list.setDivider(null);
list.setDividerHeight(0);
setContentView(list);

在 MyAdapter class:

      private class MyAdapter extends ArrayAdapter<SOCIAL_POST> {

            TextView listText;
            ImageView listImage;
            CardView listCard;

            RelativeLayout listLayout;
            RelativeLayout.LayoutParams paramsTxt;
            RelativeLayout.LayoutParams paramsImg;
            RelativeLayout.LayoutParams paramsCardView;

            public MyAdapter(Context context, ArrayList<SOCIAL_POST> posts) {
                super(context, -1, -1, posts);
                listLayout = new RelativeLayout(SocialPage.this);

                paramsCardView = new RelativeLayout.LayoutParams(
                        RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
                paramsCardView.leftMargin = width_square*5;
                paramsCardView.rightMargin = width_square*5;
                paramsCardView.topMargin = height_square*5;
                paramsCardView.width = width_square*100;

                paramsImg = new RelativeLayout.LayoutParams(
                        RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
                paramsImg.topMargin = height_square*5;
                paramsImg.height = width_square*50;

                paramsTxt = new RelativeLayout.LayoutParams(
                        RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
                paramsTxt.leftMargin = width_square*10;
                paramsTxt.rightMargin = width_square*10;
                paramsTxt.topMargin = height_square*5;
                paramsTxt.width = width_square*80;
                paramsCardView.addRule(RelativeLayout.CENTER_HORIZONTAL);
                paramsImg.addRule(RelativeLayout.CENTER_HORIZONTAL);
            }

            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                text_height = 0;

  convertView = getLayoutInflater().inflate(R.layout.row_list_social,null);
            convertView.setPaddingRelative(width_square*5, height_square*3,
                    width_square*5, height_square*3);

            ViewHolder holder = new ViewHolder();
            holder.imageView = convertView.findViewById(R.id.rowImage);
            holder.textView = convertView.findViewById(R.id.rowText);
            holder.cardView = convertView.findViewById(R.id.rowCard);
            convertView.setTag(holder);

            holder.textView.setTextColor(Color.BLACK);

            holder.cardView.setContentPadding(width_square*5, height_square*3,
                    width_square*5, height_square*3);
            holder.cardView.setCardBackgroundColor(Color.parseColor("#FFFFFF"));

            paramsTxt.addRule(RelativeLayout.BELOW, R.id.rowImage);
            paramsCardView.addRule(RelativeLayout.BELOW, R.id.rowText);

                //check social
                String social = checkClass(String.valueOf(getItem(position).getClass()));

                switch (social){
                    case "FACEBOOK":
                        new_fb_post = (FB_POST) getItem(position);
                        if(new_fb_post.full_picture != null && !new_fb_post.full_picture.equals("")){
                            paramsImg.height = width_square*50;
                            Glide.with(mContext)
                                    .load(new_fb_post.full_picture)
                                    .into(listImage);
                        } else {
                            paramsImg.height = width_square*1;
                        }
                        text3Lines(new_fb_post.message, listText);
                        break;
                    case "OFFICIAL":
                        new_of_post = (OF_POST) getItem(position);
                        if(new_of_post.full_picture != null && !new_of_post.full_picture.equals("")){

                            paramsImg.height = width_square*50;
                            Glide.with(mContext)
                                    .load(new_of_post.full_picture)
                                    .into(listImage);
                        } else {
                            paramsImg.height = width_square*5;
                        }
                        text3Lines(new_of_post.message, listText);
                        break;
                    default:
                        break;
                }
                listCard.setLayoutParams(paramsCardView);
                listImage.setLayoutParams(paramsImg);
                listText.setLayoutParams(paramsTxt);

                return convertView;
            }
        }

这是我的 ViewHolder 结构：

static class ViewHolder {
    TextView textView;
    ImageView imageView;
    CardView cardView;
}

在此先感谢您的帮助。

Answer 1

结果相同，因为您没有正确使用 View Holder。每次调用 getView 时，您都在膨胀视图。

public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder;
    if (convertView == null) { 
   // if convertView is null 
       convertView = mInflater.inflate(R.layout.mylayout, parent, false); 
       holder = new ViewHolder(); 
       // initialize views
       convertView.setTag(holder); 
      // set tag on view
     }
    else { 
       holder = (ViewHolder) convertView.getTag(); 
       // if not null get tag // no need to initialize 
    } //update views here return convertView; 
}

ListView 延迟从底部滚动到顶部

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