Android中的二级列表-ExpandableListView-编程知识

Android中的二级下拉列表，类似于某Q的分组，采用ExpandableListView实现，适配器方法如下。

先看效果图：有四个分组，每个分组下都有一些子条目，可以跟着父条目展开而显示

实现代码：

一级列表是一个ArrayList，二级列表是一个HashMap。

    <ExpandableListViewandroid:id="@+id/expandableListView"android:layout_width="match_parent"android:layout_height="wrap_content"android:nestedScrollingEnabled="false"android:layout_weight="1"/>

     //添加一级数据项 存储一级菜单的名字ArrayList<String> firstLevelMenuList = SeatModelManager.getInstance().getTxGroups();//二级数据LinkedHashMap<String, List<String>> secondItems = new LinkedHashMap<>();ArrayList<String> txNameList;for (int i = 0; i < firstLevelMenuList.size(); i++) {ArrayList<Tx> txes = SeatModelManager.getInstance().readTxByGroup(firstLevelMenuList.get(i));txNameList = new ArrayList<>();for (int j = 0; j < txes.size(); j++) {//根据一级菜单的名字匹配自己所在的父条目if (txes.get(j).getGroup().equals(firstLevelMenuList.get(i))) {txNameList.add(txes.get(j).getTxName());}}secondItems.put(firstLevelMenuList.get(i), txNameList);}expandableListView = inflate.findViewById(R.id.expandableListView);expandableListAdapter = new ExpandableListviewAdapter(getActivity(), firstLevelMenuList, secondItems);expandableListView.setAdapter(expandableListAdapter);

适配器，构造方法里的代码根据需要进行编写

public class ExpandableListviewAdapter extends BaseExpandableListAdapter {private static final String TAG = "ExpandableListviewAdapt";private ArrayList<String> firstItems;private Map<String, List<String>> secondItems;private Map<String, boolean[]> secondItemSelection;//记录子条目选中状态private List<String> selectChildItems;//记录子条目的顺序public ExpandableListviewAdapter(Context context, ArrayList<String> firstItems, Map<String, List<String>> secondItems) {this.context = context;this.firstItems = firstItems;this.secondItems = secondItems;secondItemSelection = new HashMap<>();selectChildItems = new ArrayList<>();//初始化子条目中的顺序列表//初始化子条目的选中状态for (String first : firstItems) {int secondCunt = secondItems.get(first).size();boolean[] selection = new boolean[secondCunt];secondItemSelection.put(first, selection);}}//返回当前被选中的子条目的数据public ArrayList<String> getSelectChildItems() {ArrayList<String> selectItems = new ArrayList<>();for (String firstItem : firstItems) {boolean[] selection = secondItemSelection.get(firstItem);List<String> second = secondItems.get(firstItem);for (int i = 0; i < selection.length; i++) {if (selection[i]) {selectItems.add(second.get(i));}}}//创建新的列表 按照顺序添加子条目ArrayList<String> selectItemsInOrder = new ArrayList<>();for (String item : selectChildItems) {if (selectItems.contains(item)) {selectItemsInOrder.add(item);}}return selectItemsInOrder;}@Overridepublic int getGroupCount() {return firstItems.size();}@Overridepublic int getChildrenCount(int groupPosition) {String s = firstItems.get(groupPosition);List<String> strings = secondItems.get(s);return strings != null ? strings.size() : 0;}@Overridepublic Object getGroup(int groupPosition) {return firstItems.get(groupPosition);}@Overridepublic Object getChild(int groupPosition, int childPosition) {return secondItems.get(groupPosition);}@Overridepublic long getGroupId(int groupPosition) {return groupPosition;}@Overridepublic long getChildId(int groupPosition, int childPosition) {return childPosition;}@Overridepublic boolean hasStableIds() {return true;}@Overridepublic View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {GroupViewHolder groupViewHolder;if (convertView == null) {LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);convertView = inflater.inflate(R.layout.item_parent, null);groupViewHolder = new GroupViewHolder();groupViewHolder.parentTv = convertView.findViewById(R.id.item_parent_tv);groupViewHolder.parentTv.setText(firstItems.get(groupPosition));convertView.setTag(groupViewHolder);}return convertView;}TextView childNum;@Overridepublic View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {if (convertView == null) {LayoutInflater inflater = LayoutInflater.from(parent.getContext());convertView = inflater.inflate(R.layout.item_child, parent, false);}//设置子布局String firstItem = firstItems.get(groupPosition);boolean[] selection = secondItemSelection.get(firstItem);boolean isSelect = selection[childPosition];String secondItem = secondItems.get(firstItem).get(childPosition);TextView childText = convertView.findViewById(R.id.item_child_tv);CheckBox childCb = convertView.findViewById(R.id.item_child_cb);childNum = convertView.findViewById(R.id.item_num);childText.setText(secondItem);childCb.setChecked(isSelect);//获取当前子条目在列表中的位置int index = getChildIndex(groupPosition, childPosition);if (index > 0) {childNum.setText(String.valueOf(index));//设置数字角标childNum.setVisibility(View.VISIBLE);childCb.setChecked(true);} else {childNum.setVisibility(View.INVISIBLE);childCb.setChecked(false);}//复选框的监听事件childCb.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {boolean isChecked = childCb.isChecked();selection[childPosition] = isChecked;//处理选中的状态逻辑if (isChecked) {String childItem = secondItems.get(firstItem).get(childPosition);selectChildItems.add(childItem);} else {//子条目取消选中 移除选中的子条目String childItem = secondItems.get(firstItem).get(childPosition);selectChildItems.remove(childItem);}notifyDataSetChanged();List<String> selectChildItems = getSelectChildItems();Log.d(TAG, "getGroupView: " + selectChildItems);}});return convertView;}/*** 获取子条目在列表中的位置** @param groupPosition* @param childPosition* @return*/private int getChildIndex(int groupPosition, int childPosition) {String firstItem = firstItems.get(groupPosition);String secondItem = secondItems.get(firstItem).get(childPosition);int index = selectChildItems.indexOf(secondItem);// 由于索引从0开始，所以需要加1return index + 1;}public void setSelectChildItems(ArrayList<String> selectChildItems) {this.selectChildItems = selectChildItems;
//        for (int i = 0; i < selectChildItems.size(); i++) {
//            String s = selectChildItems.get(i);
//            for (String second : selectChildItems)
//                if (s.equals(second)) {
//
//                }
//        }notifyDataSetChanged();//更新页面显示}//指定位置上的子元素是否可选中@Overridepublic boolean isChildSelectable(int groupPosition, int childPosition) {return true;}//刷新子条目数据public void updateChildData(int groupPosition, List<String> childList) {notifyDataSetChanged();}public void updateChildView() {notifyDataSetChanged();}static class GroupViewHolder {TextView parentTv;}}