实现Viewholder设计模式的最佳方法是什么。

时间:2016-01-22 08:14:09

标签: android gridview

在你亲切地阅读之前,我已经看过已经问过的问题了。很多问题都与它们不匹配。

这些天我更多地处理自定义ListView和自定义GridView。我使用ViewHolder类进行平滑滚动。但是我注意到了一些奇怪的东西。当我向下滚动列表时,项目会不断重复,或者当我实施gridView时,ViewHolder会继续重复,因为在Android指南中是推荐的。但是,当我初始化视图时,项目不会重复。

告诉我如何才能做得更好。这使我可以平滑滚动而无需重复相同的项目。

public class GridAdapter extends BaseAdapter {
    Context context;
    Main values;
    LayoutInflater inflater;
    public GridAdapter(Context context, Main main){
        this.context=context;
        this.values=main;
        inflater = ( LayoutInflater )context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return values.getPosts().size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ImageLoader imageLoader= ImageLoader.getInstance();
        ViewHolder viewHolder = null;
        if(convertView==null){
            viewHolder = new ViewHolder();
            convertView = inflater.inflate(R.layout.grid_item,parent,false);

            convertView.setTag(viewHolder);
        }
        else {
            viewHolder=(ViewHolder)convertView.getTag();
        }
        viewHolder.image=(ImageView)convertView.findViewById(R.id.thumbnail);
        viewHolder.title=(TextView)convertView.findViewById(R.id.title);
        viewHolder.title.setText(Html.fromHtml(values.getPosts().get(position).getTitle()));
        imageLoader.displayImage(values.getPosts().get(position).getThumbnail_images().getFull().getUrl(), viewHolder.image);
        return convertView;
    }

    private static class ViewHolder{
        public static ImageView image;
        public static TextView title;
    }
}

此代码为我提供重复项目,是Android指南中的推荐方式:

public class GridAdapter extends BaseAdapter {
Context context;
Main values;
LayoutInflater inflater;
public GridAdapter(Context context, Main main){
    this.context=context;
    this.values=main;
    inflater = ( LayoutInflater )context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    return values.getPosts().size();
}

@Override
public Object getItem(int position) {
    return position;
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    ImageLoader imageLoader= ImageLoader.getInstance();
    ViewHolder viewHolder = null;
    if(convertView==null){
        viewHolder = new ViewHolder();
        convertView = inflater.inflate(R.layout.grid_item,parent,false);
    viewHolder.image=(ImageView)convertView.findViewById(R.id.thumbnail);
    viewHolder.title=(TextView)convertView.findViewById(R.id.title);
        convertView.setTag(viewHolder);
    }
    else {
        viewHolder=(ViewHolder)convertView.getTag();
    }

    viewHolder.title.setText(Html.fromHtml(values.getPosts().get(position).getTitle()));
    imageLoader.displayImage(values.getPosts().get(position).getThumbnail_images().getFull().getUrl(), viewHolder.image);
    return convertView;
}

private static class ViewHolder{
    public static ImageView image;
    public static TextView title;
}
}

1 个答案:

答案 0 :(得分:2)

 public static ImageView image;
 public static TextView title;

错了。他们应该是

public ImageView image;
public TextView title;

没有static。这应该可以解决您的问题。您可以阅读有关静态关键字here

的更多信息