ListView最佳实践

最新推荐文章于 2024-03-07 18:03:10 发布

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最新推荐文章于 2024-03-07 18:03:10 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/jiculong7893/article/details/100022540

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本文介绍了ListView的最佳实践，通过在getView()方法中利用缓存的contentView和ViewHolder模式，提高列表的滚动性能。详细讲解了如何在contentView不为空时，从tag中获取ViewHolder并更新UI元素，以实现ListView的高效数据绑定。

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思路

利用getView()中contentView参数是用于对加载好的布局的缓存，将一个存放listview的item的ui控件的holder利用view.setTag()存放在该contentView的tag中，当contentView不为null时，直接取出holder更改ui控件的显示内容即可。

代码

ListView的Adapter

public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;

    public FruitAdapter(Context context, int resource, List<Fruit> fruitList) {
        super(context, resource, fruitList);
        resourceId = resource;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = view.findViewById(R.id.fruit_image);
            viewHolder.fruitName = view.findViewById(R.id.fruit_name);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }
        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;

    }

    class ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
    }
}

使用ListView

FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        ListView listView = findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Fruit fruit = fruitList.get(i);
                Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });