Nested Elements in Java JSON with Jackson

I have a JSON string that contains nested values.

It looks something like this:

"[{"listed_count":1720,"status":{"retweet_count":78}}]"

I am interested in extracting the value of retweet_count.

Currently, I am using Jackson to work with this data.

The code snippet below is currently outputting "{retweet_count=78}" instead of just 78. I'm wondering if there is a way to access nested values similar to how it is done in PHP, for example status->retweet_count. Thank you!

import java.io.IOException;
import java.util.List;
import java.util.Map;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class tests {
public static void main(String [] args) throws IOException{
    ObjectMapper mapper = new ObjectMapper();
  List <Map<String, Object>> followers = mapper.readValue("[{\"listed_count\":1720,\"status\":{\"retweet_count\":78}}]]", new TypeReference<List <Map<String, Object>>>() {});
    System.out.println(followers.get(0).get("status"));

    }
}

Answer №1

Understanding the fundamental structure of the data you're working with is crucial for accurate representation. This allows you to access various benefits such as type safety ;)

public static class TweetData {
    public int listed_count;
    public Status status;

    public static class Status {
        public int retweet_count;
    }
}

List<TweetData> td = mapper.readValue(..., new TypeReference<List<TweetData>>() {});
System.out.println(td.get(0).status.retweet_count);

Answer №2

Consider giving this a shot. Implementing JsonNode can simplify your tasks.

JsonNode data = mapper.readValue("[{\"likes\":2020,\"post\":{\"comment_count\":45}}]]", JsonNode.class);

System.out.println(data.findValues("comment_count").get(0).asInt());

Answer №3

Extract the retweet count from your list of maps using this code:

System.out.println(fwers.get(0).get("status").get("retweet_count"));

Edit 1:

Update your code snippet to handle a List<Map<String, Map<String, Object>>> like this:

List<Map<String, Map<String, Object>>> fwers = mapper.readValue(..., new TypeReference<List<Map<String, Map<String, Object>>>>() {});

Then, retrieve the retweet count with

System.out.println(fwers.get(0).get("status").get("retweet_count"));

Remember that you are working with a map of <String, Map<String, Object>> pairs.

Edit 2:

If your data structure includes a list of maps and nested maps, ensure proper casting is applied. You can access the retweet count as follows:

Map m = (Map) fwers.get(0).get("status");
System.out.println(m.get("retweet_count"));

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