Parsing and getting nested json objects using gson java

Question

I have this json file:

{
  "Update tree": {
    "average time": 0.01610115085649609,
    "best time": 0.003310859220941582,
    "count": 651,
    "success rate": 100,
    "worst time": 0.621779361692829
  },
  "Update renderables": {
    "average time": 0.1988377572034353,
    "best time": 0.0003510859220941582,
    "count": 649,
    "success rate": 100,
    "worst time": 12.8709652214104
  },
  "Before render": {
    "average time": 0.5206290903024032,
    "best time": 0.01522995241633128,
    "count": 188,
    "success rate": 100,
    "worst time": 81.06473259514415
  },
  "Rendering": {
    "average time": 4.425231035278629,
    "best time": 0.4979532268296139,
    "count": 214,
    "success rate": 100,
    "worst time": 71.34537426614806
  },
  "After render": {
    "average time": 0.06479598048728916,
    "best time": 0.0301288189105684,
    "count": 563,
    "success rate": 100,
    "worst time": 0.6413134310963844
  }
}

where I want to calculate the average of all avergaes in each json object how do I iterate through the json objects?

I am trying to get all avergaes values sum them up and calculate their average

EDIT:

I have this for loop which I want to iterate through each object (and not getting its member name but to actually iterate through the objects and get the values and then sum them up):

for(int i=0; i<json.size(); i++){
            sumAllAverages(json.getAsJsonObject());
        }

private static void sumAllAverages(JsonObject asJsonObject) {
        sum += Float.parseFloat(asJsonObject.get("average time").toString());
    }

I'll edit my question

kim el
– kim el

2020-07-23 07:41:33 +00:00
Commented Jul 23, 2020 at 7:41 — kim el
– kim el, Commented Jul 23, 2020 at 7:41

pirho · Accepted Answer · 2020-07-23 09:27:53Z

With GSON you can just deserialize this to a map like:

Type type = new TypeToken<Map<String, Map<String, Double>>>() {}.getType();
Map<String, Map<String, Double>> map =
        new Gson().fromJson(getResourceStreamReader("file.json"), type);

getResourceStreamReader("file.json") is just a helper method to get your JSON from a resource file. It can be String or any reader.

To have all the average times (for example):

Set<Double> averageTimes = map.values().stream()
    .map(v -> v.get("average time")).collect(Collectors.toSet());

To inspect the averages from this map you can for example do this:

averageTimes.forEach(averageTime -> System.out.println(averageTime));

This produces:

0.01610115085649609
0.1988377572034353
0.5206290903024032
4.425231035278629
0.06479598048728916

Further you can use reduce to sum all the values and get the total average time;

Double totalAverageTime = averageTimes.stream()
            .reduce((a, b) -> a + b).orElse(0D) / averageTimes.size();

Inspect it:

System.out.println(totalAverageTime);

and you will see:

1.0451190028256505

Note: all this calculation may be done with yet fewer lines even in one lambda but for clarity and making it easier to follow I have splitted the phases.

V.C. · Accepted Answer · 2020-07-23 08:36:59Z

-1

This is how I do it in Jackson, gson should be fairly similar.

JsonNode time_Data;
    try {
      time_Data = new ObjectMapper().readTree(jsonTimes); // **this is your file as a string
      double sum = 0.0;
      if(time_Data!= null) {
        for (final JsonNode valuesPacket : time_Data) {
          sum += Double.parseDouble(valuesPacket.get("average time").asText());
        }
      }
      System.out.println("sum is :"+sum);
    } catch (JsonProcessingException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }

edited Jul 23, 2020 at 8:36

answered Jul 23, 2020 at 8:13

V.C.

1011 silver badge8 bronze badges

2 Comments

kim el Over a year ago

what maven dependancy are you using for the second line (e.g. readTree)

V.C. Over a year ago

<dependency>         <groupId>com.fasterxml.jackson.jaxrs</groupId>         <artifactId>jackson-jaxrs-json-provider</artifactId>         <version>2.8.8</version>       </dependency>

Collectives™ on Stack Overflow

Parsing and getting nested json objects using gson java

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related