使用 JSON-simple 将条目附加到 JSON 数组

Question

我在附加到 JSON 文件时遇到问题。我可以添加新条目，但不能将其插入正确的位置。

代码：

public static void main(String args[]) throws Exception {

    {
        File file = new File("jsonFormatting.json");
        if (!file.exists()) {
            System.out.println("No file");
        } else {
            try {
                JSONParser parser = new JSONParser();
                Object obj = parser.parse(new FileReader("jsonFormatting.json"));
                JSONObject jsonObject = (JSONObject) obj;
                JSONArray jsonItemInfo = (JSONArray) jsonObject.get("itemInfo");

                JSONObject newObject = new JSONObject();

                newObject.put("item", new Integer(10003));
                newObject.put("name", "ID10003");

                StringWriter out = new StringWriter();
                newObject.writeJSONString(out);
                String jsonText = out.toString();
                System.out.println(jsonText);

                jsonItemInfo.add(newObject);

                FileWriter fileToWrite = new FileWriter("jsonFormatting.json", true);
                try {
                    fileToWrite.write(jsonItemInfo.toJSONString());
                } catch (IOException e) {
                    e.printStackTrace();
                }
                fileToWrite.flush();
                fileToWrite.close();

            } catch (IOException | ParseException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

JSON 文件:

"sampleArray": [
    "Element_0",
    "Element_1"
],
"dataPoint_1": 40,
"dataPoint_2": 500,
"dataPoint_3": 650,
"itemInfo": [
    {
        "item": "10001",
        "name": "ID10001",
    },
    {
        "item": "10002",
        "name": "ID10002",
    }
]

我想在 "itemInfo" 中添加以下内容：

    {
        "item": "10003",
        "name": "ID10003",
    }

但是，当我运行我的 Java 代码时，它会将此添加到 JSON 文件的末尾，而不是在原始 2 之后插入新条目：

[{"item":"10001","name":"ID10001"},{"item":"10002","name":"ID10002"},{"item":10003,"name":"ID10003"}]

提前感谢您提供的任何建议！

Answer 1

我运行这段代码，它工作正常，你能在你这边测试一下吗？如果我理解你的问题是正确的。

public static void main(String args[]) throws Exception {

            {
                File file = new File("jsonFormatting.json");
                if (!file.exists()) {
                    System.out.println("No file");
                } else {
                    try {
                        JSONParser parser = new JSONParser();
                        Object obj = parser.parse(new FileReader("jsonFormatting.json"));
                        JSONObject jsonObject = (JSONObject) obj;
                        JSONArray jsonItemInfo = (JSONArray) jsonObject.get("itemInfo");

                        JSONObject newObject = new JSONObject();

                        newObject.put("item", new Integer(10003));
                        newObject.put("name", "ID10003");

                        StringWriter out = new StringWriter();
                        newObject.writeJSONString(out);
                        String jsonText = out.toString();
                        System.out.println(jsonText);

                        jsonItemInfo.add(newObject);
                        jsonObject.put("itemInfo", jsonItemInfo);
                        FileWriter fileToWrite = new FileWriter("jsonFormatting.json", false);
                        try {
                            fileToWrite.write(jsonObject.toJSONString());
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        fileToWrite.flush();
                        fileToWrite.close();

                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }

我的jsonFormatting.json文件数据看起来像

{"sampleArray": [
    "Element_0",
    "Element_1"
],
"dataPoint_1": 40,
"dataPoint_2": 500,
"dataPoint_3": 650,
"itemInfo": [
    {
        "item": "10001",
        "name": "ID10001"
    },
    {
        "item": "10002",
        "name": "ID10002"
    }
]
}

输出为

{
    "sampleArray": [
        "Element_0",
        "Element_1"
    ],
    "itemInfo": [
        {
            "item": "10001",
            "name": "ID10001"
        },
        {
            "item": "10002",
            "name": "ID10002"
        },
        {
            "item": 10003,
            "name": "ID10003"
        }
    ],
    "dataPoint_2": 500,
    "dataPoint_1": 40,
    "dataPoint_3": 650
}

使用 JSON-simple 将条目附加到 JSON 数组

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