java - 无法从json文件打印json数组的所有键和值

Question

我是 json 新手，我在 google 上搜索了很多，但找不到解决方案。

这是我的 json 文件

{
    "id": 1,
    "firstname": "Katerina",
    "languages": [
        {
          "lang": "en",
          "knowledge": "proficient"
        },
        {
          "lang": "fr",
          "knowledge": "advanced"
        }
    ]
}

我想获取语言数组的键和值并打印它们，如下所示:

key is: lang and value is: en
key is: knowledge and value is: proficient
key is: lang and value is: fr
key is: knowledge and value is: advanced

我使用以下代码来打印:

JSONParser parser = new JSONParser();
File file = new File("/Users/amzadhossain/Documents/jsonfile2.json");
FileReader reader = new FileReader(file);
JSONObject jsonObject = (JSONObject) parser.parse(reader);

JSONArray languages = (JSONArray) jsonObject.get("languages");

Map<String,String> map = new HashMap<String,String>();
List<Map<String, String>> lstmap = new ArrayList<Map<String, String>>();

Iterator<String> iter = null;
Iterator<String> iter2 = null;

for (int i =0; i<languages.size();i++){

    JSONObject firstarr = (JSONObject) languages.get(i);

    iter = firstarr.keySet().iterator();
    iter2 = firstarr.values().iterator();

    while(iter.hasNext()){
        String key = (String)iter.next();
        //String value = firstarr.toJSONString();
        String value = (String)iter2.next();

        map.put(key,value);
        lstmap.add(i, map);
        System.out.println(i+" *****  "+key + "#### " + map.get(key));

    }

}

for(int i=0;i<lstmap.size();i++){

    Map<String,String> mapget = lstmap.get(i);

    for (Map.Entry<String, String> entry : mapget.entrySet()) {
        System.out.println("Key : " + entry.getKey() + " Value : " + entry.getValue());
    }   
}

但问题是它只打印最后一个键和值。请帮忙。我只想通过使用简单的 json 来解决这个问题。

Answer 1

检查下面的代码。

final JSONParser parser = new JSONParser();
final File file = new File("/Users/amzadhossain/Documents/jsonfile2.json");
final FileReader reader = new FileReader(file);
final JSONObject jsonObject = (JSONObject) parser.parse(reader);
final JSONArray languages = (JSONArray) jsonObject.get("languages");
List<Map<String, String>> lstmap = new ArrayList<Map<String, String>>();
        Iterator<String> iter = null;
        for (int i = 0; i < languages.size(); i++) {
            JSONObject firstarr = (JSONObject) languages.get(i);
            iter = firstarr.keySet().iterator();            
            while(iter.hasNext()){
                final Map<String, String> map = new HashMap<String, String>();
                String key = (String)iter.next();
                Object value = firstarr.get(key); 
                map.put(key, value.toString());
                lstmap.add(map);
               System.out.println("key is "+key + " and value is " + value);
            }

        }
        for (Map<String, String> map : lstmap){
            for (Map.Entry<String, String> entry : map.entrySet()) {
                System.out.println("Key : " + entry.getKey() + " Value : " + entry.getValue());
            }
        }