java 把json数据转成数组进行操作

这里有一个数组，我们要做的先把它转成数组，然后是看他的数据里有没有“date”为12-17的日期，如果没有则新增一条。

[\n" +
                "\n" +
                "{\n" +
                "\"date\":\"12-22\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                " {\n" +
                "\"date\":\"12-17\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                " {\n" +
                "\"date\":\"12-19\",\n" +
                "  \"A\": 1999,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                "{\n" +
                "\"date\":\"12-16\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                "{\n" +
                "\"date\":\"12-19\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " }\n" +
                "]

首先我们先去pom里把这个加进去

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.4</version>
        </dependency>

输入json（记得要加双引号）

public static void main(String[] args) {
        String a = "[\n" +
                "\n" +
                "{\n" +
                "\"date\":\"12-22\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                " {\n" +
                "\"date\":\"12-17\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                " {\n" +
                "\"date\":\"12-19\",\n" +
                "  \"A\": 1999,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                "{\n" +
                "\"date\":\"12-16\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " },\n" +
                "{\n" +
                "\"date\":\"12-19\",\n" +
                "  \"A\": 10,\n" +
                "  \"B\": 13.8,\n" +
                "  \"C\": 16.8\n" +
                " }\n" +
                "]";

然后把json转成数组

JSONArray array=JSON.parseArray(a);

按“date”大小进行排序（前面需要搞一个实体类Getter和Setter还有toString）

 List<StreamTese> list = JSONObject.parseArray(array.toJSONString(),StreamTese.class);
        List streamTese=  list.stream().sorted(Comparator.comparing(StreamTese::getDate).reversed()).collect(toList());
        System.out.println(streamTese);

获取当前时间（下面要做的只是同月不同日的比较，时间格式只取“MM-dd”就可以了）

//获取系统当前时间
 Date date = new Date();
 //时间格式
 SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MM-dd");
 String now=simpleDateFormat.format(date);

继续循环判断

 boolean b=false;
        int i=0;
        for ( i = 0; i <array.size() ; i++) {
            //判断array数组中有没有和系统当前日期一样的数据“date”
            //如果数组中没有等于系统当前时间的date，b为true。
            if(!array.getJSONObject(i).getString("date").equals(now))
            {
             b=!b;
            }
        }
        //如果b为false则新增
        if (b){
            Map<String,Object> map=new HashMap<>();
            map.put("date","12-16");
            map.put("A","10");
            map.put("B","12.3");
            map.put("C","10.6");
            array.add(map);
            System.out.println(streamTese);
        }else {
            //JSONObject  jsonObject=array.getJSONObject(i-1);
            //System.out.println(jsonObject.getString("date"));
            //System.out.println(jsonObject.getString("A"));
            //System.out.println(jsonObject.getString("B"));
            //System.out.println(jsonObject.getString("C"));
            System.out.println(streamTese);
        }
    }
}

打印结果：
[{"date":"12-22","A":10,"B":13.8,"C":16.8},{"date":"12-17","A":10,"B":13.8,"C":16.8},{"date":"12-16","A":1999,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8}]
[{"date":"12-22","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":1999,"B":13.8,"C":16.8},{"date":"12-17","A":10,"B":13.8,"C":16.8},{"date":"12-16","A":10,"B":13.8,"C":16.8}]

如果数组中没有“date”为12-16的数据，则新增

打印结果：
[{"date":"12-22","A":10,"B":13.8,"C":16.8},{"date":"12-17","A":10,"B":13.8,"C":16.8},{"date":"12-16","A":1999,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8}]
[{"date":"12-22","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":10,"B":13.8,"C":16.8},{"date":"12-19","A":1999,"B":13.8,"C":16.8},{"date":"12-17","A":10,"B":13.8,"C":16.8},{"date":"12-17","A":10,"B":13.8,"C":16.8},{"date":"12-16","A":"10","B":"12.3","C":"10.6"}]