Kotlin三层嵌套ExpandableListView子项重复、二级子项不显示问题咨询

问题1：父列表子视图全部相同、groupPosition始终为0修复 #

该问题核心是父适配器的子项计数逻辑错误：你需要为每个Leg（父列表组项）仅创建1个子项承载对应的内层ExpandableListView，而非每个Step创建1个重复的内层列表。
修改JourneyLegExpandableListAdapter的getChildrenCount方法：

override fun getChildrenCount(groupPosition: Int): Int {
    // 每个Leg仅对应1个内层ExpandableListView子项
    return 1
}

问题2：子列表子视图不显示修复 #

该问题由两个原因导致：布局高度配置错误、嵌套滚动组件高度未正确测量，按以下步骤修改：

1. 修正所有嵌套层级布局的高度配置
   所有ExpandableListView及其父容器的android:layout_height属性改为wrap_content，禁止在可滚动容器内使用match_parent：

• leg_detail_group_view根节点MaterialCardView高度改为wrap_content
• steps_nested_list_view根LinearLayout和内部ExpandableListView高度改为wrap_content
• steps_nested_group_view根节点MaterialCardView高度改为wrap_content
• step_detail_view根节点MaterialCardView和内部RelativeLayout高度改为wrap_content

2. 新增动态测量内层ExpandableListView高度的工具方法
   避免滚动冲突导致内层列表高度被压缩为0：

private fun setNestedExpandableHeight(listView: ExpandableListView) {
    val adapter = listView.adapter ?: return
    var totalHeight = 0
    val widthSpec = View.MeasureSpec.makeMeasureSpec(listView.width, View.MeasureSpec.EXACTLY)
    // 累加所有组项高度
    for (i in 0 until adapter.groupCount) {
        val groupView = adapter.getGroupView(i, listView.isGroupExpanded(i), null, listView)
        groupView.measure(widthSpec, View.MeasureSpec.UNSPECIFIED)
        totalHeight += groupView.measuredHeight
        // 累加展开状态的子项高度
        if (listView.isGroupExpanded(i)) {
            for (j in 0 until adapter.getChildrenCount(i)) {
                val childView = adapter.getChildView(i, j, j == adapter.getChildrenCount(i)-1, null, listView)
                childView.measure(widthSpec, View.MeasureSpec.UNSPECIFIED)
                totalHeight += childView.measuredHeight
            }
        }
        // 累加分割线高度
        totalHeight += listView.dividerHeight * (adapter.getChildrenCount(i) + 1)
    }
    // 重新设置列表高度
    val params = listView.layoutParams
    params.height = totalHeight + listView.paddingTop + listView.paddingBottom
    listView.layoutParams = params
    listView.requestLayout()
}

3. 内层列表设置适配器后触发高度计算，同步监听展开/折叠状态更新高度
   修改JourneyLegExpandableListAdapter的getChildView方法：

override fun getChildView(
    groupPosition: Int,
    childPosition: Int,
    isLastChild: Boolean,
    convertView: View?,
    parent: ViewGroup?
): View {
    val v: View
    if (convertView == null) {
        v = LayoutInflater.from(con).inflate(R.layout.steps_nested_list_view, parent, false)
    } else {
        v = convertView
    }
    val childList: ExpandableListView = v.findViewById(R.id.steps_nested_expandable_list_view)
    val adapter = StepsExpandableListAdapter(con, parentList.get(groupPosition).steps)
    childList.setAdapter(adapter)
    // 新增部分：计算高度+监听状态更新
    setNestedExpandableHeight(childList)
    childList.setOnGroupExpandListener { setNestedExpandableHeight(childList) }
    childList.setOnGroupCollapseListener { setNestedExpandableHeight(childList) }
    return v
}

4. 修复空指针隐患
   修改StepsExpandableListAdapter的getChildrenCount方法，避免subSteps为空时崩溃：

override fun getChildrenCount(groupPosition: Int): Int {
    return parentList[groupPosition].subSteps?.size ?: 0
}

内容的提问来源于stack exchange，提问作者codeblogger