连接两个HashMap值

Question

我有这个JSON字符串:

String json = "{"countries":{"2":"China","3":"Russia ","4":"USA"},"capitals":{"2":Beijing,"4":null,"3":Moscow}}";我将string转换为HashMap，使用如下:

HashMap<String,Object> map = new Gson().fromJson(json, new TypeToken<HashMap<String, Object>>(){}.getType());
System.out.println(map.get("countries")+"@@@@@"+map.get("capitals"));

现在输出是:

{2=China, 3=Russia , 4=USA}@@@@@{2=Beijing, 4=null, 3=Moscow}

我想用数字连接这些值。我想创建两个这样的数组列表:

)——(中国、俄罗斯、美国)

B) -(北京、莫斯科、零)

我该怎么做呢?

Answer 1

首先，你需要将map.get("label")转换为LinkedTreeMap<Integer, String>，然后用它的值创建新的ArrayList

String json = "{"countries":{"2":"China","3":"Russia ","4":"USA"},"capitals":{"2":Beijing,"4":null,"3":Moscow}}";
HashMap<String,TreeMap<Integer, String>> map = new Gson().fromJson(json, new TypeToken<HashMap<String, TreeMap<Integer, String>>>(){}.getType());
ArrayList<String> countries = new ArrayList<>(map.get("countries").values());
System.out.println(countries);
ArrayList<String> capitals = new ArrayList<>(map.get("capitals").values());
System.out.println(capitals);

Answer 2

您可以遍历国家键集以填充大写数组:

List<String> countries = new ArrayList<>(countriesMap.values());
List<String> capitals = new ArrayList<>();
for (String countryKey : countriesMap.keySet()) {
capitals.add(capitalsMap.get(countryKey));
}