ListView 的内容占用大量内存

Question

ListView 包含相当多的项目（20 或更多），每个项目都是带有位图源的 ImageView。这些位图未压缩，大小约为 640x480。当 ListView 刚刚加载时，它会占用一些内存，但如果我滚动它，则可能会发生错误 "Memory exceed VM budjet"。当我用另一个片段替换片段时，ListView 仍然挂在内存中。如何清除 ram/ListView 缓存？

更新：

我使用SimpleCursorAdapter 和ViewBinder：

    SimpleCursorAdapter.ViewBinder viewBinder = new SimpleCursorAdapter.ViewBinder() {
        public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
            if (columnIndex == 0) {
                TextView tv1 = (TextView) view;
                if (cursor.getInt(4) == 0)
                    tv1.setTextColor(Color.GRAY);
                else
                    tv1.setTextColor(Color.parseColor("#191919"));
                tv1.setText(cursor.getString(columnIndex));
            }
            if (columnIndex == 3) {
                TextView tv1 = (TextView) view;
                tv1.setText(cursor.getString(columnIndex));
            }
            if (columnIndex == 2) {
                final ImageView image = (ImageView) view;
                Bitmap cachedImage = null;
                try {
                    cachedImage = imageThreadLoader.loadImage(cursor.getString(columnIndex), new ImageThreadLoader.ImageLoadedListener() {
                        public void imageLoaded(Bitmap imageBitmap) {
                            image.setImageBitmap((Bitmap) new SoftReference(imageBitmap).get());
                        }
                    });
                } catch (MalformedURLException mue) {
                    Log.e("Feeds fragment", "Can't load image");
                }
                if (cachedImage != null) {
                    image.setImageBitmap(cachedImage);
                } else image.setImageDrawable(getResources().getDrawable(R.drawable.icon));
            }

图像在单独的线程中加载。

Answer 1

我建议您观看有关 ListViews 的 Google IO presentation。它包含节省内存的技术，它帮助我理解了 ListViews 的逻辑。

Answer 2

像这样构建列表视图，制作您的自定义适配器并将其设置为列表视图

public class InteractiveArrayAdapter extends ArrayAdapter<Model> {

    private final List<Model> list;
    private final Activity context;

    public InteractiveArrayAdapter(Activity context, List<Model> list) {
        super(context, R.layout.main, list);
        this.context = context;
        this.list = list;
    }

    static class ViewHolder {
        protected TextView text;
        protected CheckBox checkbox;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = null;
        if (convertView == null) {
            LayoutInflater inflator = context.getLayoutInflater();
            view = inflator.inflate(R.layout.main, null);
            final ViewHolder viewHolder = new ViewHolder();
            viewHolder.text = (TextView) view.findViewById(R.id.listitem_text);
            viewHolder.checkbox = (CheckBox) view.findViewById(R.id.checkBox1);
            viewHolder.checkbox
                    .setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

                        public void onCheckedChanged(CompoundButton buttonView,
                                boolean isChecked) {
                            Model element = (Model) viewHolder.checkbox
                                    .getTag();
                            element.setSelected(buttonView.isChecked());

                        }
                    });
            view.setTag(viewHolder);
            viewHolder.checkbox.setTag(list.get(position));
        } else {
            view = convertView;
            ((ViewHolder) view.getTag()).checkbox.setTag(list.get(position));
        }
        ViewHolder holder = (ViewHolder) view.getTag();
        holder.text.setText(list.get(position).getName());
        holder.checkbox.setChecked(list.get(position).isSelected());
        return view;
    }
}

试试这个方法，你不必要的视图会被回收，执行会更快，希望你能摆脱错误