Read date values from a JSON file into Java HashMap

I have a JSON file that looks like this:

{
    "calendar": {
        "dateToDayId": {
            "2016-07-14": 290356,
            "2016-08-26": 380486,
            "2016-09-07": 417244,
            "2016-08-15": 354271,
            "2016-07-25": 311762
        },
        "dishIdToMealId": {
            "1228578": 474602,
            "1228585": 474602,
            "1228586": 474602,
        ...... // more fields
}

I'm trying to read the <date, number> pairs under dateToDayId into a HashMap<Date, Long> in java. First I created a JsonInfo class which holds a Calendar class object. The Calendar class object in turns holds all the classes including DateToDayId, DishToMealId and so on. My DateToDayId class looks like this (I'm using Jackson to parse JSON file):

package jsonfields;

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import deserializers.CustomDateDeserializer;

import java.util.Date;
import java.util.TreeMap;

public class DateToDayId {
    @JsonDeserialize(using = CustomDateDeserializer.class)
    private TreeMap <Date, Long> dateToDayMappings;

    public TreeMap<Date, Long> getDateToDayMappings() {
        return dateToDayMappings;
    }

    public void setDateToDayMappings(TreeMap<Date, Long> dateToDayMappings) {
        this.dateToDayMappings = dateToDayMappings;
    }

    @Override
    public String toString() {
        return "DateToDayId{" +
                "dateToDayMappings=" + dateToDayMappings +
                '}';
    }
}

My Main class looks like this:

import java.io.*;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {
    public static void main(String[] args) {
        ObjectMapper objectMapper = new ObjectMapper();
        try {
            InputStreamReader inputStreamReader = new InputStreamReader(new FileInputStream("path\\to\\file\\test.json"));
            JsonInfo jsonInfo = objectMapper.readValue(inputStreamReader, JsonInfo.class);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

When I run it, I get the following exception:

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "2016-07-14" (class jsonfields.DateToDayId), not marked as ignorable (one known property: "dateToDayMappings"])
 at [Source: (InputStreamReader); line: 1, column: 48] (through reference chain: JsonInfo["calendar"]->jsonfields.Calendar["dateToDayId"]->jsonfields.DateToDayId["2016-07-14"])

How can I fix this?

Your class mapping is wrong. You need to have map with variable name dateToDayId in Calendar. Below modified code should work for your need.

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.TreeMap;
public class JSONMapTest {
public static void main(String[] args) {
ObjectMapper objectMapper = new ObjectMapper();
try {
InputStreamReader inputStreamReader = new InputStreamReader(new FileInputStream("C:\\ws\\test\\test.json"));
JsonInfo jsonInfo = objectMapper.readValue(inputStreamReader, JsonInfo.class);
System.out.println(jsonInfo);
} catch (JsonProcessingException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
class JsonInfo{
Calendar calendar;
public Calendar getCalendar() {
return calendar;
}
public void setCalendar(Calendar calendar) {
this.calendar = calendar;
}
}
class Calendar {
private TreeMap <Date, Long> dateToDayId;
public TreeMap<Date, Long> getDateToDayId() {
return dateToDayId;
}
public void setDateToDayId(TreeMap<Date, Long> dateToDayId) {
this.dateToDayId = dateToDayId;
}
@Override
public String toString() {
return "DateToDayId{" +
"dateToDayMappings=" + dateToDayId +
'}';
}
}