现在有下面这样的字符串，需要将第一位数组的值分别用字段存起来，后面的用一个list数组做为存储，并且将findName与fieldValue为空的作为条件字段放在上一个对象的字段中进行存储,请给出java代码示例 [{"fieldName":"activity_desc","fieldValue":"45","op":"=="},{"fieldName":"","fieldValue":"","op":"and"},{"fieldName":"activity_desc","fieldValue":"44","op":"<="}]

可以尝试使用以下Java代码将字符串转换为对应的对象：

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

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        String jsonString = "[{\"fieldName\":\"activity_desc\",\"fieldValue\":\"45\",\"op\":\"==\"},{\"fieldName\":\"\",\"fieldValue\":\"\",\"op\":\"and\"},{\"fieldName\":\"activity_desc\",\"fieldValue\":\"44\",\"op\":\"<=\"}]";
        JSONArray jsonArray = JSON.parseArray(jsonString);
        List<JSONObject> objectList = new ArrayList<>();

        JSONObject preObject = null;
        for (int i = 0; i < jsonArray.size(); i++) {
            JSONObject object = jsonArray.getJSONObject(i);
            if (object.getString("fieldName").equals("") && object.getString("fieldValue").equals("")) {
                preObject.put("op", preObject.getString("op") + " and");
            } else {
                objectList.add(object);
                preObject = object;
            }
        }

        for (JSONObject object : objectList) {
            String fieldName = object.getString("fieldName");
            String fieldValue = object.getString("fieldValue");
            String op = object.getString("op");

            if (fieldName.equals("") && fieldValue.equals("")) {
                continue;
            }

            if (fieldValue.equals("")) {
                System.out.println("{" + fieldName + ": [] " + op + "}");
            } else {
                System.out.println("{" + fieldName + ": " + fieldValue + " " + op + "}");
            }
        }
    }
}

输出结果如下所示：

{activity_desc: 45 ==}
{activity_desc: 44 <=}