为什么滚动 listView 时项目会消失? [英] Why do items disappear when I scroll the listView?
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问题描述
我的应用程序使用 ListView 来显示单元格中的不同项目.它必须有照片和名称，但恰好有描述和图标.
My application use a ListView which display different items in the cell. it must have photo and name, but it happens to have description and icons.
问题是:当我滚动ListView并回到顶部时，描述和图标消失了，只有图像和名称.我的印象是描述和图标已被删除，每行都具有相同的大小.
The problem is: when I scroll the ListView and come back to the top, the description and icons have disappeared, there are only image and name. I have the impression the description and icons have been removed to have the same size for each row.
我为我的 ListView 使用自定义适配器 (BaseAdapter):
I use a custom adapter (BaseAdapter) for my ListView:
public class MyAdapterPark extends BaseAdapter {
private ArrayList<DataPark> datapark;
private LayoutInflater myInflater;
public MyAdapterPark (Context context, ArrayList<DataPark> _datapark)
{
this.myInflater = LayoutInflater.from(context);
this.datapark = _datapark;
}
@Override
public int getCount() {
return this.datapark.size();
}
@Override
public Object getItem(int arg0) {
return this.datapark.get(arg0);
}
@Override
public long getItemId(int position) {
return position;
}
public static class ViewHolder {
ImageView image;
TextView text01;
ImageView facebook;
ImageView twitter;
ImageView linkedin;
ImageView blog;
ImageView music;
TextView bio;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView == null)
{
convertView = myInflater.inflate(R.layout.affichageitem, null);
holder = new ViewHolder();
holder.image = (ImageView)convertView.findViewById(R.id.img);
holder.text01 = (TextView)convertView.findViewById(R.id.user);
holder.facebook = (ImageView)convertView.findViewById(R.id.facebook);
holder.twitter = (ImageView)convertView.findViewById(R.id.twitter);
holder.linkedin = (ImageView)convertView.findViewById(R.id.linkedin);
holder.blog = (ImageView)convertView.findViewById(R.id.blog);
holder.music = (ImageView)convertView.findViewById(R.id.music);
holder.bio = (TextView)convertView.findViewById(R.id.bio);
convertView.setTag(holder);
}else{
holder = (ViewHolder) convertView.getTag();
}
holder.text01.setText(datapark.get(position).nickname);
if (!(datapark.get(position).pic.equals(""))){
try {
//byte[] decodedString;
//decodedString = Base64.decode(datapark.get(position).pic);
//Bitmap bitmap = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
//holder.image.setImageBitmap(bitmap);
holder.image.setImageBitmap(telechargerImage(datapark.get(position).pic));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else{
holder.image.setImageResource(R.drawable.profilbase);
}
if (!(datapark.get(position).facebook.equals(""))){
holder.facebook.setImageResource(R.drawable.fb);
}else{
((ImageView)convertView.findViewById(R.id.facebook)).setVisibility(View.GONE);
}
if (!(datapark.get(position).twitter.equals(""))){
holder.twitter.setImageResource(R.drawable.twitter);
}else{
((ImageView)convertView.findViewById(R.id.twitter)).setVisibility(View.GONE);
}
if (!(datapark.get(position).linkedin.equals(""))){
holder.linkedin.setImageResource(R.drawable.linkedin);
}else{
((ImageView)convertView.findViewById(R.id.linkedin)).setVisibility(View.GONE);
}
if (! (datapark.get(position).blog.equals(""))){
holder.blog.setImageResource(R.drawable.blog);
}else{
((ImageView)convertView.findViewById(R.id.blog)).setVisibility(View.GONE);
}
if (!(datapark.get(position).music.equals(""))){
holder.music.setImageResource(R.drawable.music);
}else{
((ImageView)convertView.findViewById(R.id.music)).setVisibility(View.GONE);
}
if (!(datapark.get(position).bio.equals(""))){
holder.bio.setText(datapark.get(position).bio);
}else{
((TextView)convertView.findViewById(R.id.bio)).setVisibility(View.GONE);
}
return convertView;
}
public static Bitmap telechargerImage(String url) {
Bitmap bm = null;
try {
URL aURL = new URL(url);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
} catch (IOException e) {
Log.e("Erreur","Erreur lors de la récupération de l'image : " + e.getMessage().toString());
}
return bm;
}
}
还有我的适配器的 XML:
And the XML of my adapter:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#eaf4f0"
>
<ImageView
android:id="@+id/img"
android:layout_width="70px"
android:layout_height="70px"
android:background="@drawable/carre"
android:scaleType="fitXY"
android:padding="5sp"
android:layout_marginLeft="0sp"
android:src="@drawable/profilbase"
android:layout_margin="5sp"
/>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:paddingLeft="0sp"
android:layout_weight="1"
>
<TextView android:id="@+id/user"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="14px"
android:textColor="#000000"
android:textStyle="bold"
android:text=""
android:layout_marginTop="5sp"
/>
<TextView android:id="@+id/bio"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="14px"
android:textColor="#000000"
android:layout_marginTop="1sp"
android:layout_marginRight="2sp"
android:text=""
/>
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="4sp"
android:layout_marginBottom="4sp"
>
<ImageView
android:id="@+id/facebook"
android:layout_width="17px"
android:layout_height="17px"
android:scaleType="fitXY"
android:layout_gravity="center"
/>
<ImageView
android:id="@+id/twitter"
android:layout_width="17px"
android:layout_height="17px"
android:scaleType="fitXY"
android:layout_gravity="center"
android:layout_marginLeft="5sp"
/>
<ImageView
android:id="@+id/linkedin"
android:layout_width="17px"
android:layout_height="17px"
android:scaleType="fitXY"
android:layout_gravity="center"
android:layout_marginLeft="5sp"
/>
<ImageView
android:id="@+id/blog"
android:layout_width="17px"
android:layout_height="17px"
android:scaleType="fitXY"
android:layout_gravity="center"
android:layout_marginLeft="5sp"
/>
<ImageView
android:id="@+id/music"
android:layout_width="17px"
android:layout_height="17px"
android:scaleType="fitXY"
android:layout_gravity="center"
android:layout_marginLeft="5sp"
/>
</LinearLayout>
</LinearLayout>
</LinearLayout>
谢谢！
推荐答案
这是因为您有时会隐藏某些视图，并且再也不会显示它们.示例:
It's because you're hiding some of your views sometimes, and you never show them again. Example:
if (!(datapark.get(position).bio.equals(""))){
holder.bio.setText(datapark.get(position).bio);
}else{
((TextView)convertView.findViewById(R.id.bio)).setVisibility(View.GONE);
}
改为尝试:
if (!(datapark.get(position).bio.equals(""))){
holder.bio.setVisibility(View.VISIBLE);
holder.bio.setText(datapark.get(position).bio);
}else{
holder.bio.setVisibility(View.GONE);
}
请记住，视图是循环使用的，因此，除非您在下次返回视图时显示这些视图，否则它们将永远不会再次可见.另外，请记住，holder.bio 与 findViewById 返回的内容相同，因此您可以在 else 块中执行 holder.bio.setVisibility(View.GONE).
Remember that views are recycled, so, unless you show the views the next time you return one, they will never be visible again. Also, remember that holder.bio is the same thing that is returned by the findViewById, so you can do holder.bio.setVisibility(View.GONE) in the else block.
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