Kotlin ExpandableListView可擴展二級串列

1.Kotlin 實作可擴展二級串列效果如下

......
        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/mRecyclerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/bgColorSecondary"
            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
......

3.MainActivity.kt

......
        var nodeAdapter = StatisticsAdapter()
        mRecyclerView.adapter = nodeAdapter
        nodeAdapter.setList(nodelist)
......
        var groups = getGroups()
        groups.forEach {
            //設定item node
            setItemNode(it)
        }
......
    private fun setItemNode(groupName: String) {
        val items: MutableList<BaseNode> = mutableListOf()
        if (groupName.contains("統計1")) {
            var s = StatisticsNode("辦公室統計", "1", null)
            items.add(s);
            s = StatisticsNode("宿舍統計", "2", null)
            items.add(s)
            s = StatisticsNode("教室統計", "3", null)
            items.add(s)
            val entity = RootNode(items, groupName)
            nodelist.add(entity)
        }
        if (groupName.contains("統計2")) {
            var s = StatisticsNode("食堂統計", "4", null)
            items.add(s);
            s = StatisticsNode("超市統計", "5", null)
            items.add(s);
            s = StatisticsNode("物業室統計", "6", null)
            items.add(s);
            val entity = RootNode(items, groupName)
            nodelist.add(entity)
        }
    }

    private fun getGroups(): ArrayList<String> {
        var groupName = arrayListOf<String>()
        groupName.add("統計1")
        groupName.add("統計2")
        return groupName
    }
......

3.1 StatisticsAdapter.kt

3.1.1 RootNodeProvider.kt，點擊item

    override fun onClick(helper: BaseViewHolder, view: View, data: BaseNode, position: Int) {
        getAdapter()!!.expandOrCollapse(position)
    }

3.1.2 StatisticsNodeProvider.kt

    override fun onClick(helper: BaseViewHolder, view: View, data: BaseNode, position: Int) {
        val entity: StatisticsNode = data as StatisticsNode
        if ("2" == entity.classity) {
            val intent = Intent(MyApplication.context, StatisticsActivity::class.java)
            context?.startActivity(intent)
        }
    }

4.activity_expandable_listview.xml，這是擴展二級串列的

......
        <ExpandableListView
            android:id="@+id/elvContent"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:groupIndicator="@null" />
......

5.StatisticsActivity.kt
5.1

    fun initView() {
        adapter = DetailExpandableListAdapter(this)
        elvContent.setAdapter(adapter)
    }

5.2 可以自己設定資料，注意：必須要有規律,代碼(注釋說明)如下

        fun initDatas() {
            //"1"表示標題
            var sc = SitCode(1, "1", "一棟宿舍");list.add(sc)
            //"1A"表示第一組
            sc = SitCode(2, "1A", "宿舍2001");list.add(sc)
            //"1AA","1AB","1AC","1AD"表示子選項
            sc = SitCode(3, "1AA", "小紅");list.add(sc)
            sc = SitCode(4, "1AB", "小彬");list.add(sc)
            sc = SitCode(5, "1AC", "小強");list.add(sc)
            sc = SitCode(6, "1AD", "小紅");list.add(sc)
            //"1B"表示第二組
            sc = SitCode(7, "1B", "宿舍2002");list.add(sc)
            //"1BA","1BB"表示子選項
            sc = SitCode(8, "1BA", "小可");list.add(sc)
            sc = SitCode(9, "1BB", "小雪");list.add(sc)
            sc = SitCode(10, "1BC", "小飛");list.add(sc)
            //"1C"表示第三組
            sc = SitCode(11, "1C", "宿舍2003");list.add(sc)
            //"1CA","1CB","1CC"表示子選項
            sc = SitCode(12, "1CA", "小和");list.add(sc)
            sc = SitCode(13, "1CB", "小楊");list.add(sc)
            sc = SitCode(14, "1CC", "小一");list.add(sc)
            //"1D"表示第四組
            sc = SitCode(15, "1D", "宿舍2004");list.add(sc)
            //"2"表示標題
            sc = SitCode(16, "2", "二棟宿舍");list.add(sc)
            //"2A"表示第五組
            sc = SitCode(17, "2A", "宿舍2005");list.add(sc)
            //"2B"表示第六組
            sc = SitCode(18, "2B", "宿舍2006");list.add(sc)
            //"2BA","2BB","1CC"表示子選項
            sc = SitCode(19, "2BA", "小山");list.add(sc)
            sc = SitCode(20, "2BB", "小梅");list.add(sc)
            //"2C"表示第七組
            sc = SitCode(21, "2C", "宿舍2007");list.add(sc)
            //"3"表示標題
            sc = SitCode(22, "3", "三棟宿舍");list.add(sc)
            //"3A"表示第八組
            sc = SitCode(23, "3A", "宿舍2008");list.add(sc)
            //"3B"表示第九組
            sc = SitCode(24, "3B", "宿舍2009");list.add(sc)
            //"3C"表示第十組
            sc = SitCode(25, "3C", "宿舍2010");list.add(sc)
            //"4"表示標題
            sc = SitCode(26, "4", "四棟宿舍");list.add(sc)
......    

5.2.1 我做開發時就用sqlite資料庫上設定資料比較好，需要和SQL Server一致，如下圖

如何用代碼獲取sqlite資料庫的資料，你需要的話，可以點擊
Kotlin開發 如何獲取SQLite資料庫上自己創建規律的可擴展二級串列資料
5.3 代碼(注釋說明)如下

......
            for (sitcode in list) {
                val code = sitcode.code
                //如果code是“1”或者“1A”或者“1AB”
                when (code.length) {
                //組資料給groups,groups包括有標題和組
                    //"1"的長度是1就給groups賦值
                    1 -> groups.add(sitcode)
                    //"1A"的長度是2就給groups賦值
                    2 -> groups.add(sitcode)
                    else -> {
                    //1AB(子選項)的長度是3就給對應的group賦值
                        val groupCode = code.substring(0, 2)
                        var childs = groupChilds[groupCode]
                        if (childs == null) {
                            childs = ArrayList()
                            groupChilds[groupCode] = childs
                        }
                        childs.add(sitcode)
                    }
                }
            }
......

5.4 獲取指定組位置處的組資料

        override fun getGroupView(groupPosition: Int, isExpanded: Boolean, convertView: View?, parent: ViewGroup?): View {
            var convertView = convertView
            var viewHolder: ViewHolder = ViewHolder.getViewHolder(inflater, convertView, parent, R.layout.item_ser_detail)
            val sitCode = getGroup(groupPosition)
            convertView = viewHolder.convertView
            val iv: ImageView = viewHolder.getView(R.id.iv_ser) as ImageView
            //如果sitCode.code=“1A”(組)
            if (sitCode.code.length == 2){
                //如果“1A”有子選項“1AA”
                if (list[sitCode.id].code.length == 3 ){
                     //把箭頭開了
                    iv.visibility = View.VISIBLE
                }
            }else{
                //如果“1A”沒有子選項，箭頭就隱去
                iv.visibility = View.GONE
            }

            iv.setImageResource(R.mipmap.ic_arrow_down)
            if (!isExpanded) {
                iv.setImageResource(R.mipmap.ic_arrow_right)
            }
            convertView.setBackgroundResource(
                if (sitCode.code.length == 1)
                    R.drawable.alert_info_shap
                else
                    R.color.white
            )
            val NameTv: TextView = viewHolder.getView(R.id.tv_ser_name)
            val paddingDip = TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP,
                12f,
                PhoneU.getScreenPix(context)
            ).toInt()
            NameTv.setPadding(paddingDip, paddingDip, paddingDip, paddingDip)
            NameTv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 16f)
            var text = ""
            if (sitCode.code.length == 1) {
                text = sitCode.name
            } else if (sitCode.code.length == 2) {
                text = sitCode.name
            }
            viewHolder.setText(R.id.tv_ser_name, text)
            viewHolder.setTextColor(R.id.tv_ser_name, Color.RED)
            return convertView
        }

5.5 該方法決定每個子選項的外觀

override fun getChildView(groupPosition: Int, childPosition: Int, isLastChild: Boolean,
                                  convertView: View?, parent: ViewGroup?): View {
            var convertView = convertView
            val viewHolder: ViewHolder = ViewHolder.getViewHolder(inflater, convertView, parent, R.layout.item_ser_detail)
            convertView = viewHolder.convertView
            convertView.setBackgroundResource(R.color.white)
            val NameTv: TextView = viewHolder.getView(R.id.tv_ser_name)
            ......
            val Code = getChild(groupPosition, childPosition)
            viewHolder.setText(R.id.tv_ser_name, Code?.name)
            return convertView

        }

5.6 源代碼zip下載：
下載源代碼