懒人ListView适配器

「爱情、让人受尽委屈。」 2022-05-27 01:22 220阅读 0赞

# 懒人ListView适配器 #

### 适配器 ###

#  #

public abstract class CommonAdaper<T> extends BaseAdapter {
        private Context context;
        private List<T> list;
    
    
        public CommonAdaper(Context context, List<T> list) {
            this.context = context;
            this.list = list;
        }
    
        @Override
        public int getCount() {
            return list == null ? 0 : list.size();
        }
    
        @Override
        public T getItem(int position) {
            return list.get(position);
        }
    
        @Override
        public long getItemId(int position) {
            return position;
        }
    
        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder holder = ViewHolder.get(view, viewGroup, 列表子项布局的id, i);
            convert(holder, getItem(i));
            return holder.getConvertView();
        }
    
        public abstract void convert(ViewHolder holder, T item);
    
    }

### ViewHolder【这个是核心：不变的在CommonAdaper，变得在ViewHolder】 ###

#  #

public class ViewHolder {
        //现在对于int作为键的官方推荐用SparseArray替代HashMap
        private final SparseArray<View> views;
        private int position;
        private View convertView;
        private Context context;
    
        private ViewHolder(Context context, ViewGroup parent, int layoutId, int position) {
            this.context = context;
            this.views = new SparseArray<>();
            this.convertView = LayoutInflater.from(parent.getContext()).inflate(layoutId, parent, false);
            convertView.setTag(this);
        }
    
        /**
         * 拿到一个ViewHolder对象
         */
        public static ViewHolder get(View convertView, ViewGroup parent, int layoutId, int position) {
            if (convertView == null) {
                return new ViewHolder(parent.getContext(), parent, layoutId, position);
            }
            return (ViewHolder) convertView.getTag();
        }
    
        /**
         * 通过控件的Id获取对于的控件，如果没有则加入views
         */
        public <T extends View> T getView(int viewId) {
            View view = views.get(viewId);
            if (view == null) {
                view = convertView.findViewById(viewId);
                views.put(viewId, view);
            }
            return (T) view;
        }
    
        public View getConvertView() {
            return convertView;
        }
    
        /**
         * 设置字符串
         */
        public ViewHolder setText(int viewId, String text) {
            TextView tv = getView(viewId);
            tv.setText(text);
            return this;
        }
    
        /**
         * 设置图片
         */
        public ViewHolder setImageResource(int viewId, int drawableId) {
            ImageView iv = getView(viewId);
            iv.setImageResource(drawableId);
            return this;
        }
    
        /**
         * 设置图片
         */
        public ViewHolder setImageBitmap(int viewId, Bitmap bitmap) {
            ImageView iv = getView(viewId);
            iv.setImageBitmap(bitmap);
            return this;
        }
    
        public int getPosition() {
            return position;
        }
    }

### Activity中调用【结合你的实际需求写】 ###

#  #

public class XXActivity extends Activity {
        //声明控件
        private ListView listView;
        //声明数据
        private List<实体类> list;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_select_school);
    
            listView = (ListView) findViewById(列表对应的id);
            initList();
    
            listView.setAdapter(new CommonAdaper<实体类>(this, list) {
                @Override
                public void convert(ViewHolder holder, SchoolData item) {
                    holder.setText(列表子项的TextView对应的的id, item.getName());
                    holder.setImageResource(列表子项ImageView对应的id, item.getImg_id());
                }
            });
        }
    
        private void initList() {
            list = new ArrayList<实体类>();
            for (int i = 0; i < 10; i++) {
                list.add(new SchoolData());
            }
        }
    }

### 布局就不写了，你能收到说明你的前面的工作应该没问题（相信你）！！ ###