Question

我的代码中有Hashmap的ArrayList 我有混淆，我应该使用哪种排序方法？我的代码如下

arraylist = new ArrayList<HashMap<String, String>>();
            // Retrieve JSON Objects from the given URL address
            jsonobject = JSONFunctions
                        .getJSONfromURL("https://api.foursquare.com/v2/venues/search?    client_id=ACAO2JPKM1MXHQJCK45IIFKRFR2ZVL0QASMCBCG5NPJQWF2G&client_secret=YZCKUYJ1W    HUV2QICBXUBEILZI1DMPUIDP5SHV043O04FKBHL&v=20130815&ll=-34.678,138.87&radius=5000&section=coffee");

        try {
            // Locate the array name in JSON
            jsonarray = jsonobject.getJSONObject("response");

            JSONArray jsonSubarray = jsonarray.getJSONArray("venues");
            Log.v("Response Array", String.valueOf(jsonSubarray));



            for (int i = 0; i < jsonSubarray.length(); i++) {
                HashMap<String, String> map = new HashMap<String, String>();

                jsonobject = jsonSubarray.getJSONObject(i);
                // Retrive JSON Objects
                // Retrive JSON Objects

                Log.v("Store name", jsonobject.getString("name"));
                map.put("storeName", jsonobject.getString("name"));

                JSONObject locationObject = jsonobject.getJSONObject("location");
                Log.v("if condition",String.valueOf( locationObject.has("city")));
                if(locationObject.has("city"))
                {
                    map.put("city", locationObject.getString("city"));
                }
                else
                    map.put("city","N/A");

                double km = Double.valueOf(locationObject.getString("distance")) / 1000 ;
                Log.v("distance", String.valueOf(km));
                map.put("distance", String.valueOf(km));

                arraylist.add(map);

            }
        } catch (JSONException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

这是我的JSON数据格式

"id": "4e321829d4c00077f657b8ec",
            "name": "TeAro Estate Wines",
            "contact": {},
            "location": {
                "lat": -34.670859098532766,
                "lng": 138.89067804714347,
                "distance": 2053,
                "cc": "AU",
                "city": "Williamstown",
                "state": "SA",
                "country": "Australia",
                "formattedAddress": [
                    "Williamstown SA",
                    "Australia"
                ]
            },
            "categories": [
                {
                    "id": "4bf58dd8d48988d14b941735",
                    "name": "Winery",
                    "pluralName": "Wineries",
                    "shortName": "Winery",
                    "icon": {
                        "prefix": "https://ss3.4sqi.net/img/categories_v2/food/winery_",
                        "suffix": ".png"
                    },
                    "primary": true
                }
            ],
        {
            "id": "4c454825f0bdd13a65c9cacc",
            "name": "Barossa Dam",
            "contact": {},
            "location": {
                "address": "Dam it",
                "lat": -34.645353,
                "lng": 138.848115,
                "distance": 4150,
                "cc": "AU",
                "city": "Sandy Creek",
                "state": "SA",
                "country": "Australia",
                "formattedAddress": [
                    "Dam it",
                    "Sandy Creek SA",
                    "Australia"
                ]
            },

我想按距离排序请给我一些关于我应该使用什么方法的建议我对数组列表和哈希映射的数组列表感到困惑我如何使用collection.sort对数据进行排序。

我想根据ArrayList中的值进行排序。

Answer 1

使用比较器对其进行排序。

Comparator<HashMap<String, String>> distanceComparator = new Comparator<HashMap<String,String>>() {

    @Override
    public int compare(HashMap<String, String> o1, HashMap<String, String> o2) {
        // Get the distance and compare the distance.
        Integer distance1 = Integer.parseInt(o1.get("distance"));
        Integer distance2 = Integer.parseInt(o2.get("distance"));

        return distance1.compareTo(distance2);
    }
};

// And then sort it using collections.sort().
Collections.sort(arrayList, distanceComparator);

Answer 2

Collections.sort(arrayList, (HashMap<String, String> m1, HashMap<String, String> m2) -> 
            Integer.parseInt(m1.get("distance").compareTo(Integer.parseInt(m2.get("distance")))));

使用java 1.8和Lambda表达式功能的一个想法更简洁。

sort ArrayList <hashmap <string，string =“”>＆gt;使用价值

2 个答案: