Question

i write some jsp to generate a json, but in one case,i meet a problem,
i put order and get order are not same,
i put 1,2,3,4,5 to jsonarray, but it seem return me a wrong order 3,2,5,1,4
that is my code in jsp:

Map map = new LinkedHashMap();  
Iterator itor = listView.getList().iterator();
JSONObject json = new JSONObject();
JSONArray jArray = new JSONArray();

while ( itor.hasNext() ) {
    current = (EvidPackageDao) itor.next();
    map.put("id", current.getPackageId());
    map.put("packno", current.getPackageNo());
    map.put("photocover", current.getPhotoCover());
    map.put("photoback", current.getPhotoBack());
    map.put("evidi", current.getEvidIndentification());
    map.put("type", current.getEvidType());
    map.put("verno", current.getVersionNo());
    map.put("isbn", current.getIsbn());
    map.put("pub", current.getPublisher());
    map.put("distr", current.getDistributor());
    map.put("producer", current.getProducer());
    map.put("cprl", current.getCoptrightLogo());
    map.put("cprt", current.getCopyrightText());
    map.put("reason", current.getIllegalReason());

    Iterator it = map.entrySet().iterator();

    while (it.hasNext()) 
            {
           Map.Entry entry = (Map.Entry) it.next();
        Object key = entry.getKey();
        Object value = entry.getValue();
        System.out.println("key=" + key + ", value=" + value);

    }

            /*
             print:
        key=id, value=81
        key=packno, value=fsdfdsfsdf
        key=photocover, value=null
        key=photoback, value=null
        key=evidi, value=sdfsadf
        key=type, value=dsfsdf
        key=verno, value=sdfasdfl
        key=isbn, value=3224jsfklf
        key=pub, value=fdsjkla
        key=distr, value=lkfjl;dsfklj
        key=producer, value=fdafjdsl;
        key=cprl, value=sdfjadlfkj
        key=cprt, value=sdfadff
        key=reason, value=fdsfdsafasf

            */
    jArray.put(map);
    System.out.println(jArray.toString());
            /*
            print:
               [{"reason":null,"distr":null,"type":null,"pub":null,"verno":null,"id":82,"cprl":null,"isbn":null,"evidi":null,"photoback":null,"producer":null,"packno":null,"photocover":null,"cprt":null},{"reason":"fdsfdsafasf","distr":"lkfjl;dsfklj","type":"dsfsdf","pub":"fdsjkla","verno":"sdfasdfl","id":81,"cprl":"sdfjadlfkj","isbn":"3224jsfklf","evidi":"sdfsadf","photoback":null,"producer":"fdafjdsl;","packno":"fsdfdsfsdf","photocover":null,"cprt":"sdfadff"}]
            */

}

so how can i get the right order same with my put to the hashmap??????? like [{“id”:null, ?

Answer 1

Which library are you using? I am using the json-simple library and the following code worked:

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Map map = new LinkedHashMap();
    JSONArray jArray = new JSONArray();


    map.put("id", "aaaaaa");
    map.put("packno", "bbbbb");
    map.put("photocover", "cccccc");
    map.put("photoback", "ddddd");
    map.put("evidi", "eeeeee");
    map.put("type", "ffffff");


    jArray.add(map);
    System.out.println(jArray.toString());

}

Output:

[{"id":"aaaaaa","packno":"bbbbb","photocover":"cccccc","photoback":"ddddd","evidi":"eeeeee","type":"ffffff"}]