map添加元素保持添加时顺序不变

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要用LinkedHashMap

Map map=new LinkedHashMap();

invoicesdismap.put("a","1");
invoicesdismap.put("b","2");
invoicesdismap.put("c","3");

Set<String> key_set = null;
if (list_map.size() >= 1) {
    key_set = list_map.get(0).keySet();
}

for (int i = 0; i < map.size(); i++) {
    Map<String, Object> map1 = map.get(i);

String line = "";
for (String key : key_set) {
    String content = String.valueOf(map1.get(key));
    line = line + ((StringUtils.isBlank(content) || content == null || "null".equals(content)) ? "" : content) + split_mark;
}

}

这样line="1,2,3"