jsonArray中按字段排序

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONException;
import com.alibaba.fastjson.JSONObject;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class Demo {
    public static void main(String[] args) {
        String jsonArrStr = "[{\"ID\":\"A01\",\"Name\":\"張三\",\"Score\":88},{\"ID\":\"A02\",\"Name\":\"李四\",\"Score\":99},{\"ID\":\"A01\",\"Name\":\"王五\",\"Score\":77}]";
        System.out.println("排序前：" + jsonArrStr);
        String jsonArraySort = jsonArraySort(jsonArrStr);
        System.out.println("排序后：" + jsonArraySort);
    }


    public static String jsonArraySort(String jsonArrStr) {
        // json字符串轉為JSONArray
        JSONArray jsonArr = JSON.parseArray(jsonArrStr);
        //存放排序結果json數組
        JSONArray sortedJsonArray = new JSONArray();
        // 用於排序的list
        List<JSONObject> list = new ArrayList<JSONObject>();
        //遍歷待排序的json數組，並將數據放入list
        for (int i = 0; i < jsonArr.size(); i++) {
            list.add(jsonArr.getJSONObject(i));
        }

        Collections.sort(list, new Comparator<JSONObject>() {
            //排序字段
            private static final String KEY_NAME1 = "ID";
            private static final String KEY_NAME2 = "Score";

            @Override
            public int compare(JSONObject a, JSONObject b) {
                String valA1 = new String();
                String valA2 = new String();
                String valB1 = new String();
                String valB2 = new String();
                try {
                    valA1 = a.getString(KEY_NAME1);
                    valA2 = b.getString(KEY_NAME1);
                    valB1 = a.getString(KEY_NAME2);
                    valB2 = b.getString(KEY_NAME2);
                } catch (JSONException e) {
                    System.out.println(e);
                }
                // 設置排序規則
                int i = valA1.compareTo(valA2);
                if (i == 0) {
                    int j = valB1.compareTo(valB2);
                    return j;
                }
                return i;
            }
        });
        //將排序后結果放入結果jsonArray
        for (int i = 0; i < jsonArr.size(); i++) {
            sortedJsonArray.add(list.get(i));
        }
        return sortedJsonArray.toString();
    }
}

結果：

排序前：[{"ID":"A01","Name":"張三","Score":88},{"ID":"A02","Name":"李四","Score":99},{"ID":"A01","Name":"王五","Score":77}]
排序后：[{"Score":77,"ID":"A01","Name":"王五"},{"Score":88,"ID":"A01","Name":"張三"},{"Score":99,"ID":"A02","Name":"李四"}]

 

Lambda 表達式

 

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

import java.util.Comparator;

public class Test2 {
    public static void main(String[] args) {
        String str = "[{\"score\":77,\"id\":\"A04\"},{\"score\":88,\"id\":\"A01\"},{\"score\":66,\"id\":\"A01\"}]";
        System.out.println("排序前: " + str);
        JSONArray array = JSON.parseArray(str);

        for (Object arr : array) {
            System.out.println(arr);
        }

        // 方式一
//        array.sort(Comparator.comparing(obj -> ((JSONObject)obj).getInteger("score")));
//        array.sort(Comparator.comparing(e-> ((JSONObject)e).getString("id")));
        // 方式二：單字段排序
//        array.sort((a, b) -> ((JSONObject) a).getString("id").compareTo(((JSONObject) b).getString("id")));
        // 方式二：多字段排序
        array.sort((a, b) -> {
            int i = ((JSONObject) a).getString("id").compareTo(((JSONObject) b).getString("id"));
            if (i == 0) {
                int j = ((JSONObject) a).getInteger("score").compareTo(((JSONObject) b).getInteger("score"));
                return j;
            }
            return i;
        });
        System.out.println("排序后: " + array);

        for (Object arr : array) {
            System.out.println(arr);
        }
    }
}

結果：