按List中的map某个key进行排序

排序：Map<String,List<Map>> list_groupBy = pageList.stream().collect(Collectors.groupingBy(e->getGroupByElement(e)));

排序、求和：Map<String,Integer> asset_count_num = pageList.stream().collect(Collectors.groupingBy(e->getGroupByElement(e),Collectors.summingInt(e->Integer.parseInt(e.get("asset_count")==null?"0":e.get("asset_count").toString()))));

排序、求和：Map<String,Double> init_value_num = pageList.stream().collect(Collectors.groupingBy(e->getGroupByElement(e),Collectors.summingDouble(e->Double.parseDouble(e.get("init_value")==null?"0":e.get("init_value").toString()))));

按List<Map>中map的某个字段进行排序：Collections.sort(listMap , (o1, o2) -> o2.get("code").toString().compareTo(o1.get("code").toString()));

public String getGroupByElement(Map<String,Object>map){

    // 返回排序字段
    String ele =String.valueOf(map.get("isShow"))+","+String.valueOf(map.get("isFrozen"))+","+String.valueOf(map.get("width"));
    return ele;
}