Question

我正在设计一个这样的菜单：

它几乎可以工作，但是有一个问题。菜单在开始时工作正常，但在再次向上和向上滚动后，项目会消失并再次下载，这需要一些时间。有没有办法设置一些元素在开始时创建并防止它们消失？

这是我的代码：

public class MyActivity extends Activity implements AdapterView.OnItemClickListener {

    String headers[];
    String image_urls[];

    List<MyMenuItem> menuItems;
    ListView mylistview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        menuItems = new ArrayList<MyMenuItem>();
        headers = getResources().getStringArray(R.array.header_names);
        image_urls = getResources().getStringArray(R.array.image_urls);


        for (int i = 0; i < headers.length; i++) {
            MyMenuItem item = new MyMenuItem(headers[i], image_urls[i]);
            menuItems.add(item);
        }

        mylistview = (ListView) findViewById(R.id.list);
        MenuAdapter adapter = new MenuAdapter(this, menuItems);
        mylistview.setAdapter(adapter);
        mylistview.setOnItemClickListener(this);
    }
}




public class MyMenuItem {

    private String item_header;
    private String item_image_url;

    public MyMenuItem(String item_header, String item_image_url){
        this.item_header=item_header;
        this.item_image_url=item_image_url;
    }

    public String getItem_header(){
        return item_header;
    }

    public void setItem_header(String item_header){
        this.item_header=item_header;
    }

    public String getItem_image_url(){
        return item_image_url;
    }

    public void setItem_image_url(String item_image_url){
        this.item_image_url=item_image_url;
    }


}






public class MenuAdapter extends BaseAdapter{

    Context context;
    List<MyMenuItem> menuItems;

    MenuAdapter(Context context, List<MyMenuItem> menuItems) {
        this.context = context;
        this.menuItems = menuItems;
    }

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

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

    @Override
    public long getItemId(int position) {
        return menuItems.indexOf(getItem(position));
    }

    private class ViewHolder {
        ImageView ivMenu;
        TextView tvMenuHeader;
    }



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

        ViewHolder holder = null;

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.menu_item, null);
            holder = new ViewHolder();

            holder.tvMenuHeader = (TextView) convertView.findViewById(R.id.tvMenuHeader);
            holder.ivMenu = (ImageView) convertView.findViewById(R.id.ivMenuItem);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        MyMenuItem row_pos = menuItems.get(position);

        Picasso.with(context)
                .load(row_pos.getItem_image_url())
             //   .placeholder(R.drawable.empty)
             //   .error(R.drawable.error)
                .into(holder.ivMenu);

        holder.tvMenuHeader.setText(row_pos.getItem_header());

        Log.e("Test", "headers:" + row_pos.getItem_header());
        return convertView;
    }

}

Answer 1

可能你可以通过某种图像缓存或者你正在下载的任何东西来实现延迟加载......

Answer 2

您说图像已下载，我认为图像来自互联网。在使用

之前，为http下载或下载实现自定义缓存并将图像存储在一个位置

如何在屏幕外显示自定义列表视图项目？

2 个答案: