Performance optimization of ListView

ListView is one of the commonly used controls in Android, which is used to display a large amount of data in a list. Due to the large amount of data, performance optimization is required when using ListView to enhance user experience.

Here are some methods to optimize the performance of a ListView.

1. Implementing the ViewHolder pattern: This pattern helps to improve performance by reducing the number of findViewById calls. The ViewHolder is a static class used to store the view components of ListView items, avoiding the need to repeatedly search for views.

class MyAdapter extends BaseAdapter {
    class ViewHolder {
        TextView textView;
        ImageView imageView;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.item_layout, parent, false);
            holder = new ViewHolder();
            holder.textView = convertView.findViewById(R.id.textview);
            holder.imageView = convertView.findViewById(R.id.imageview);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        // 对holder中的视图组件进行操作
        holder.textView.setText(dataList.get(position).getText());
        holder.imageView.setImageResource(dataList.get(position).getImageRes());

        return convertView;
    }
}

1. Use pagination: If the list contains a large amount of data, consider using pagination to reduce the amount of data loaded at once and improve the responsiveness of the list. More data can be dynamically loaded by listening to scroll events.

listView.setOnScrollListener(new AbsListView.OnScrollListener() {
    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        // 滚动停止时，判断是否需要加载更多数据
        if (scrollState == SCROLL_STATE_IDLE && listView.getLastVisiblePosition() == adapter.getCount() - 1) {
            // 加载更多数据
            loadMoreData();
        }
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        // 滚动过程中不需要做任何操作
    }
});

1. Utilize image caching: To avoid loading the same images repeatedly in a list, consider using image caching. Popular image caching libraries include Picasso, Glide, and others.

Glide.with(context).load(imageUrl).into(imageView);

1. Use partial refresh: If only some of the data is changed, you can use the ListView’s partial refresh method to update list items instead of reloading the entire list.

public void updateItem(int position) {
    int visiblePosition = listView.getFirstVisiblePosition();
    View view = listView.getChildAt(position - visiblePosition);
    if (view != null) {
        // 更新视图
    }
}

1. Using stable IDs: Enhance the performance of the list by setting setHasStableIds(true) if the IDs of the list items are stable. This allows ListView to better determine which items need to be redrawn while scrolling.
2. Consider using asynchronous loading in order to improve the responsiveness of the list by avoiding blocking the main thread, especially when loading data for the list is a time-consuming operation.

new AsyncTask<Void, Void, List<Item>>() {
    @Override
    protected List<Item> doInBackground(Void... voids) {
        // 后台加载数据
        return loadData();
    }

    @Override
    protected void onPostExecute(List<Item> items) {
        // 更新UI
        adapter.setData(items);
        adapter.notifyDataSetChanged();
    }
}.execute();

In general, performance optimization for ListView includes reducing layout hierarchy, minimizing redundant view creation, asynchronous data loading, etc. The appropriate optimization method can be chosen based on specific circumstances.