我的列表视图中存在滞后问题。
因此，当我向下滚动列表视图时，性能非常出色，但当我向上滚动时，发现我的行时会出现延迟。
我使用滑行来观看图像。
我的适配器中的方法text3Lines在textView中设置了三行文本。 我的适配器中的checkClass方法包含一个简单的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 类中：
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;
}
提前感谢您的帮助。
答案 0 :(得分：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 class GPSdata
{
public TimeSpan time { get; set; } //time (in seconds, advances by 0.2)
public int latDegrees { get; set; } //Latitude
public int latMinutes { get; set; } //Latitude
public int latSeconds { get; set; } //Latitude
public string NS { get; set; } //North/South
public int lonDegrees { get; set; } //Longtitude
public int lonMinutes { get; set; } //Longtitude
public int lonSeconds { get; set; } //Longtitude
public string EW { get; set; } //East/West
public decimal knots { get; set; } //Speed in Knots
public DateTime date { get; set; } //Date [ddmmyy]
public int sats { get; set; } //**No clue**
public decimal HDOP { get; set; } //Satelite Horizontal error
public decimal alt { get; set; } //Elevation (above msl)
public int rawSV { get; set; } //Space Vehicle
}
public static List<GPSdata> LoadCSV(string filepath)
{
List<GPSdata> data = new List<GPSdata>();
using (StreamReader reader = new StreamReader(filepath))
{
while (!reader.EndOfStream)
{
string line = reader.ReadLine();
string[] values = line.Split(',');
GPSdata gpsdata = new GPSdata();
gpsdata.time = new TimeSpan((long)(decimal.Parse(values[0]) * (decimal)1.0E07));
int latDecimalPoint = values[1].IndexOf(".");
gpsdata.latSeconds = int.Parse(values[1].Substring(latDecimalPoint + 1));
gpsdata.latMinutes = int.Parse(values[1].Substring(latDecimalPoint - 2, 2));
gpsdata.latDegrees = int.Parse(values[1].Substring(0, latDecimalPoint - 2));
gpsdata.NS = values[2];
int lonDecimalPoint = values[3].IndexOf(".");
gpsdata.lonSeconds = int.Parse(values[3].Substring(lonDecimalPoint + 1));
gpsdata.lonMinutes = int.Parse(values[3].Substring(lonDecimalPoint - 2, 2));
gpsdata.lonDegrees = int.Parse(values[3].Substring(0, lonDecimalPoint - 2));
gpsdata.EW = values[4];
gpsdata.knots = decimal.Parse(values[5]);
int dateLen = values[6].Length;
gpsdata.date = new DateTime(int.Parse(values[6].Substring(dateLen - 2)), int.Parse(values[6].Substring(0, dateLen - 4)), int.Parse(values[6].Substring(dateLen - 4, 2)));
gpsdata.sats = int.Parse(values[7]);
gpsdata.HDOP = decimal.Parse(values[8]);
gpsdata.rawSV = int.Parse(values[9]);
gpsdata.alt = decimal.Parse(values[10]);
data.Add(gpsdata);
}
}
return data;
}