JSONObject jsonObject = new JSONObject();

        JSONArray jsonArray = new JSONArray();

        try {

            jsonObject.put("a","1");

            jsonObject.put("b","2");

            jsonObject.put("c","3");

            jsonObject.put("d","4");

            for(int i=0;i<10;i++){

                JSONObject object = new JSONObject();

                object.put("name",i+"");

                jsonArray.put(object);

            }

            jsonObject.put("abcd",jsonArray);

        } catch (JSONException e) {

            e.printStackTrace();

        }

        Log.e("MainActivity",jsonObject.toString());

        try {

            JSONObject object = new JSONObject(jsonObject.toString());

            Log.e("MainActivity",object.toString());

        } catch (JSONException e) {

            e.printStackTrace();

        }

11-13 14:14:13.846 15433-15433/com.example.apple.demo E/MainActivity:
 {"a":"1","b":"2","c":"3","d":"4","abcd":[{"name":"0"},{"name":"1"},{"name":"2"},{"name":"3"},{"name":"4"},{"name":"5"},{"name":"6"},{"name":"7"},{"name":"8"},{"name":"9"}]}

11-13 14:14:13.846 15433-15433/com.example.apple.demo E/MainActivity: 
{"a":"1","b":"2","c":"3","d":"4","abcd":[{"name":"0"},{"name":"1"},{"name":"2"},{"name":"3"},{"name":"4"},{"name":"5"},{"name":"6"},{"name":"7"},{"name":"8"},{"name":"9"}]}

 HashMap<String,String>map = new HashMap<>();

 map.put("a","1");

 map.put("b","2");

 map.put("c","3");

 String json = JSON.toJSONString(map);//map转String

 JSONObject jsonObject = JSON.parseObject(json);//String转json

 //json转map

  Map<String, String> jsonMap = JSONObject.toJavaObject(jsonObject, Map.class);

  //String转map

  Map<String, String> jsonMap1 = JSONObject.parseObject(json, Map.class);