将Object对象toString()再转化成想要的类型最后加减乘除操作一波
List<Map<String, Object>> list...
for (Map<String, Object> map : list) {
JYJG = Integer.parseInt(map.get("JYJG").toString())+JYJG;
...
}
Map<String, Object> map = new HashMap<String, Object>();
map.put("name", "合计");
map.put("JYJG", JYJG);
...
list.add(map);