向上滾動ListView與不同項目的高度

Question

我有ListView，包括具有不同高度的項目。當我向上滾動時，它不光滑，並且會產生跳躍效果。所有項目都有wrap_content高度。我怎樣才能平滑地向上滾動？

這裏的適配器代碼：

public class EventFeedAdapter extends ArrayAdapter<Post> { 

public EventFeedAdapter(Context context, List<Post> items) { 
    super(context, R.layout.item_event_feed, items); 
} 

@Override 
public View getView(int position, View convertView, ViewGroup arg2) { 
    if (convertView == null) { 
     convertView = View.inflate(getContext(), R.layout.item_event_feed, 
       null); 
     ViewHolder vh = new ViewHolder(); 
     vh.avatar = (ImageView) convertView.findViewById(R.id.avatar); 
     vh.photo = (ImageView) convertView.findViewById(R.id.photo); 
     vh.textName = (TextView) convertView.findViewById(R.id.textName); 
     vh.textTime = (TextView) convertView.findViewById(R.id.textTime); 
     vh.progress = (ProgressBar) convertView.findViewById(R.id.progress); 
     vh.buttonLike = (ImageView) convertView 
       .findViewById(R.id.buttonLike); 
     vh.buttonMore = (ImageView) convertView 
       .findViewById(R.id.buttonMore); 
     vh.textLikes = (TextView) convertView.findViewById(R.id.textLikes); 
     convertView.setTag(vh); 
    } 

    final ViewHolder holder = (ViewHolder) convertView.getTag(); 

    Post post = getItem(position); 
    String name = post.isFake() ? UserModel.get().getUser().getName() 
      : post.getDisplayName(); 
    String avatar = post.isFake() ? UserModel.get().getUser() 
      .getPictureUrl() : post.getProfileThumb(); 
    String mediaUrl = post.isFake() ? String.format("file://%s", 
      post.getLocalMediaUri()) : post.getMediaFeed().getUrl(); 

    ImageLoader.getInstance().displayImage(mediaUrl, holder.photo, 
      new ImageLoadingListener() { 

       @Override 
       public void onLoadingStarted(String imageUri, View view) { 
        holder.progress.setVisibility(View.VISIBLE); 
       } 

       @Override 
       public void onLoadingFailed(String imageUri, View view, 
         FailReason failReason) { 
        holder.progress.setVisibility(View.GONE); 
       } 

       @Override 
       public void onLoadingComplete(String imageUri, View view, 
         Bitmap loadedImage) { 
        holder.progress.setVisibility(View.GONE); 
       } 

       @Override 
       public void onLoadingCancelled(String imageUri, View view) { 
        holder.progress.setVisibility(View.GONE); 
       } 
      }); 

    ImageLoader.getInstance().displayImage(avatar, holder.avatar); 
    holder.textName.setText(name); 
    Date date = post.isFake() ? post.getLocalDate() : post.getCreatedAt(); 
    holder.textTime.setText(DateUtils.getFormattedDate(getContext(), date)); 
    holder.buttonLike 
      .setImageResource(post.isLocalLiked() ? R.drawable.icon_heart_filled 
        : R.drawable.icon_heart); 
    if (post.isLocalLiked() && post.getLocalLikesCount() == 1) 
     holder.textLikes.setText(R.string.you_like_this); 
    else if (post.getLocalLikesCount() > 0) 
     holder.textLikes.setText(String.format(
       getContext().getString(R.string.likes), 
       post.getLocalLikesCount())); 
    else 
     holder.textLikes.setText(""); 

    holder.buttonLike.setTag(post); 
    holder.buttonMore.setTag(post); 

    return convertView; 
} 

class ViewHolder { 
    ImageView photo; 
    ImageView avatar; 
    ImageView buttonLike; 
    ImageView buttonMore; 
    TextView textName; 
    TextView textTime; 
    ProgressBar progress; 
    TextView textLikes; 
} 
} 

如果我使用固定高度的項目滾動精品工程。

Answer 1

所以，你在哪裏使用 「VH」？據我所知，你必須包含一個「else」語句並使用你所定義的「holder」變量。否則，我懷疑持有者可能爲空，並且無論convertView爲空，都會每次調用getView。我認爲...這有幫助嗎？

編輯：糟糕！我的推理是錯誤的..當然你保證轉換的觀點是不爲空。不過，試試這個無論如何..

@Override 
public View getView(int position, View convertView, ViewGroup arg2) { 
final ViewHolder holder; 
if (convertView == null) { 
    convertView = View.inflate(getContext(), R.layout.item_event_feed, 
      null); 


    holder.avatar = (ImageView) convertView.findViewById(R.id.avatar); 
    holder.photo = (ImageView) convertView.findViewById(R.id.photo); 
    holder.textName = (TextView) convertView.findViewById(R.id.textName); 
    holder.textTime = (TextView) convertView.findViewById(R.id.textTime); 
    holder.progress = (ProgressBar) convertView.findViewById(R.id.progress); 
    holder.buttonLike = (ImageView) convertView 
      .findViewById(R.id.buttonLike); 
    holder.buttonMore = (ImageView) convertView 
      .findViewById(R.id.buttonMore); 
    holder.textLikes = (TextView) convertView.findViewById(R.id.textLikes); 
    convertView.setTag(holder); 
} 
else 
{ 

    holder=(ViewHolder) convertView.getTag(); 
} 


Post post = getItem(position); 
String name = post.isFake() ? UserModel.get().getUser().getName() 
     : post.getDisplayName(); 
String avatar = post.isFake() ? UserModel.get().getUser() 
     .getPictureUrl() : post.getProfileThumb(); 
String mediaUrl = post.isFake() ? String.format("file://%s", 
     post.getLocalMediaUri()) : post.getMediaFeed().getUrl(); 

ImageLoader.getInstance().displayImage(mediaUrl, holder.photo, 
     new ImageLoadingListener() { 

      @Override 
      public void onLoadingStarted(String imageUri, View view) { 
       holder.progress.setVisibility(View.VISIBLE); 
      } 

      @Override 
      public void onLoadingFailed(String imageUri, View view, 
        FailReason failReason) { 
       holder.progress.setVisibility(View.GONE); 
      } 

      @Override 
      public void onLoadingComplete(String imageUri, View view, 
        Bitmap loadedImage) { 
       holder.progress.setVisibility(View.GONE); 
      } 

      @Override 
      public void onLoadingCancelled(String imageUri, View view) { 
       holder.progress.setVisibility(View.GONE); 
      } 
     }); 

ImageLoader.getInstance().displayImage(avatar, holder.avatar); 
holder.textName.setText(name); 
Date date = post.isFake() ? post.getLocalDate() : post.getCreatedAt(); 
holder.textTime.setText(DateUtils.getFormattedDate(getContext(), date)); 
holder.buttonLike 
     .setImageResource(post.isLocalLiked() ? R.drawable.icon_heart_filled 
       : R.drawable.icon_heart); 
if (post.isLocalLiked() && post.getLocalLikesCount() == 1) 
    holder.textLikes.setText(R.string.you_like_this); 
else if (post.getLocalLikesCount() > 0) 
    holder.textLikes.setText(String.format(
      getContext().getString(R.string.likes), 
      post.getLocalLikesCount())); 
else 
    holder.textLikes.setText(""); 

holder.buttonLike.setTag(post); 
holder.buttonMore.setTag(post); 

return convertView; 

}