public abstract class MyBaseExpandableAdapter<P, C> extends BaseExpandableListAdapter {
    protected Context mContext;
    protected List<P> mParentList;
    protected List<List<C>> mChildList;
    protected int mParentLayout;
    protected int mChildLayout;

    /**
     * 参数过多，使用构造者模式？
     */
    public MyBaseExpandableAdapter(Context mContext, List<P> mParentList, List<List<C>> mChildList, int parentLayout,
                                   int childLayout) {
        this.mContext = mContext;
        this.mParentList = mParentList;
        this.mChildList = mChildList;
        this.mParentLayout = parentLayout;
        this.mChildLayout = childLayout;
    }

    public abstract void convertParent(ViewHolder holder, P p, int groupPosition, boolean isExpanded);

    public abstract void convertChild(ViewHolder holder, P p, C c, int groupPosition, int childPosition, boolean isLastChild);

    @Override
    public int getGroupCount() {
        return mParentList == null ? 0 : mParentList.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return (mChildList == null || mChildList.size() <= groupPosition || mChildList.get(groupPosition) == null) ?
                0 : mChildList.get(groupPosition).size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return mParentList == null ? null : mParentList.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return (mChildList == null || mChildList.size() <= groupPosition || mChildList.get(groupPosition) == null) ?
                null : mChildList.get(groupPosition).get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        ViewHolder holder = ViewHolder.getInstance(mContext, convertView, mParentLayout);
        convertParent(holder, mParentList.get(groupPosition), groupPosition, isExpanded);
        return holder.getConvertView();
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        ViewHolder holder = ViewHolder.getInstance(mContext, convertView, mChildLayout);
        convertChild(holder, mParentList.get(groupPosition), mChildList.get(groupPosition).get(childPosition), groupPosition, childPosition, isLastChild);
        return holder.getConvertView();
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true; // 子列表可以点击
    }

}

ViewHolder

/**
 * 适配器通用的ViewHolder,而且 BaseAdapter 和 BaseExpandableListAdapter 都可以用
 */

public class ViewHolder {

    private View convertView;
    private SparseArray<View> views; // SparseArray效率比HashMap更高

    private ViewHolder(View convertView) {
        this.views = new SparseArray<>();
        this.convertView = convertView;
        convertView.setTag(this);
    }

    public static ViewHolder getInstance(Context context, View convertView, int layout) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(layout, null);
            return new ViewHolder(convertView);
        }
        return (ViewHolder) convertView.getTag(); // 重用convertView的逻辑
    }

    public <T extends View> T findViewById(int id) {
        View view = views.get(id);
        if (view == null) {
            view = convertView.findViewById(id);
            views.append(id, view);
        }
        return (T) view;
    }

    public View getConvertView() {
        return convertView;
    }
}

使用方式：

public class TodaySignAdapter extends MyBaseExpandableAdapter<SignGroup, Record> {  
  
    public TodaySignAdapter(List<List<Record>> childLists, List<SignGroup> parentList, Context context) {  
        super(context, parentList, childLists,  
                R.layout.expandable_list_today_group, R.layout.expandable_list_today_child);  
    }  
  
    @Override  
    public void convertParent(ViewHolder holder, SignGroup signGroup, int groupPosition, boolean isExpanded) {  
        ImageView groupArrow = holder.findViewById(R.id.iv_group_arrow);  
        ImageView groupImage = holder.findViewById(R.id.iv_sign_group);  
        TextView signInfo = holder.findViewById(R.id.tv_sign_info);  
        TextView locationName = holder.findViewById(R.id.tv_sign_location_name);  
  
        signInfo.setText("打卡" + signGroup.signCount + "次/" + signGroup.duration);  
        locationName.setText(signGroup.locationName);  
        groupArrow.setImageResource(isExpanded ? R.mipmap.arrow_o : R.mipmap.arrow_n);  
        ImageLoader.getInstance().displayImage(URLs.HEAD_URL + signGroup.fileName, groupImage);  
    }  
  
    @Override  
    public void convertChild(ViewHolder holder, SignGroup signGroup, Record record, int groupPosition, int childPosition, boolean isLastChild) {  
        ImageView childImage = holder.findViewById(R.id.iv_sign_file_name);  
        TextView dateSign = holder.findViewById(R.id.tv_sign_date);  
  
        ImageLoader.getInstance().displayImage(URLs.HEAD_URL + record.getFileName(), childImage);  
        dateSign.setText(TimeTransferUtil.getTime(Long.parseLong(record.getDateSign())));  
    }  
  
}