List<Map<String,Object>> to org.json.JSONObject?
Solution 1
public String listmap_to_json_string(List<Map<String, Object>> list)
{
JSONArray json_arr=new JSONArray();
for (Map<String, Object> map : list) {
JSONObject json_obj=new JSONObject();
for (Map.Entry<String, Object> entry : map.entrySet()) {
String key = entry.getKey();
Object value = entry.getValue();
try {
json_obj.put(key,value);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
json_arr.put(json_obj);
}
return json_arr.toString();
}
alright, try this~ This worked for me :D
Solution 2
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
Map<String, Object> map = new HashMap<String, Object>();
map.put("abc", "123456");
map.put("def", "hmm");
list.add(map);
// it's wrong JSONObject json = new JSONObject(list);
// if u use list to add data u must be use JSONArray
JSONArray json = JSONArray.fromObject(list);
try {
System.err.println(json.toString(2));
} catch (JSONException e) {
e.printStackTrace();
}
Solution 3
You need to end up with a JSONArray (corresponding to the List) of JSONObjects (the Map).
Try declaring the json variable as a JSONArray instead of a JSONObject (I believe the JSONArray constructor will do the right thing).
Solution 4
Also: you could consider using one of other parsers from json.org's list: most of them allow your Json "objects" and "arrays" to map natively to java.util.Maps and java.util.Lists; or in some cases to real Java objects too.
My recommendation would be Jackson, http://jackson.codehaus.org/Tutorial which allows for mapping to List/Map/Integer/String/Boolean/null, as well as to real Beans/POJOs. Just give it the type and it maps data to you, or writes Java objects as Json. Others like "json-tools" from berlios, or google-gson also expose similar functionality.
Solution 5
If you are using org.json.simple.JSONArray
(https://mvnrepository.com/artifact/com.googlecode.json-simple/json-simple/1.1.1)
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
Map<String, Object> map = new HashMap<String, Object>();
map.put("abc", "123456");
map.put("def", "hmm");
list.add(map);
JSONArray jsonArray = new JSONArray();
jsonArray.addAll(listOfMaps);
David N
Updated on March 24, 2020Comments
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David N about 4 years
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); Map<String, Object> map = new HashMap<String, Object>(); map.put("abc", "123456"); map.put("def", "hmm"); list.add(map); JSONObject json = new JSONObject(list); try { System.err.println(json.toString(2)); } catch (JSONException e) { e.printStackTrace(); }
What's wrong with this code?
The output is:
{"empty": false}
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David N over 15 yearsWhat about the case where there is a JavaBean, which contains a collection that contains Map elements, and I would like to new JSONObject(myJavaBean)? I tried and wasn't satisfied.
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Admin over 11 yearsIt's '12 and I'm looking at the answer :) I'm looking at making something very similar to this (particularly an ArrayList of HashMaps) and this is helping out considerably.