序列化为日期时间、对象

Question

I have map in this format,

HashMap<String, Object> map = {"RequestsServed":{"2019-06-28T00:00:00Z":0.0},"PullRequests":{"2019-06-28T00:00:00Z":0.0}} 

My intension is to do map.get("RequestsServed") and get a map of {"2019-06-28T00:00:00Z":0.0} irrespective of number of key, value pair in it.

I tried using,

HashMap<DateTime, Object> result = new ObjectMapper().readValue(SerializationUtils.toJson(map.get("RequestsServed").toString()), HashMap.class);

and failed. please help. Thanks

Answer 1

I was so dumb asking this question...

map.get("RequestsServed") is gonna give me a LinkedTreeMap. I just have to parse it into a HashMap of my choice.

serialising map.get("RequestsServed") to a json and parse the resultant value to HashMap will give me the required result easily.

Thank you all for your time.

Answer 2

I have written a dummy class for testing purpose:

public class TempObject {
    private String date;
    private Double value;

    public TempObject(String date, Double value) {
        this.date = date;
        this.value = value;
    }

    public String getDate() {
        return date;
    }

    public Double getValue() {
        return value;
    }
}

And here is your solution:

// Initializing the Map (I'm using LinkedHashMap here for a reason)
Map<String, Object> map = new LinkedHashMap<>();
map.put("RequestsServed", new TempObject("2019-06-28T00:00:00Z", 0.0));
map.put("PullRequests", new TempObject("2019-06-28T00:00:00Z", 0.1));

// Using Collectors.toMap() with mergeFunction (to handle duplicate keys)
Map<String, Object> result = map.values().stream().map(object -> (TempObject) object).collect(Collectors.toMap(TempObject::getDate, TempObject::getValue, (existingValue, newValue) -> newValue));

System.out.println(result); // printing the value of result map: {2019-06-28T00:00:00Z=0.1}

You can also parse this String value to LocalDateTime .