I am trying to parse huge JSON data. I can't give the JSON content here in this question. But you can see actual data at this link:-
https://drive.google.com/file/d/1p3lfaQ_k3C9DB3qA3W72IGiefwLUhCzm/view
I know there popular libraries like GSON and Jackson. I tired GSON as:-
JsonParser jsonParser = new JsonParser();
JsonElement element = jsonParser.parse(line); // line contains all json data
But JsonElement has no suitable method to get data by json key.
My intentions is to parse the data which is a array in the json data. How can I do it?
JsonElement is the parent class for all nodes that the GSON parser returns. In your case the root node is a JsonObject, so it's safe to cast the element to that or use the convenience accessor getAsJsonObject.
JsonObject has the API you need for field access, and JsonArray has the API for array access:
JsonElement root = new JsonParser()
.parse(new FileReader("data.json"));
JsonArray data = root.getAsJsonObject()
.getAsJsonObject("dataset_data")
.getAsJsonArray("data");
System.out.println(data.size());
You can use this simple json library
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20180130</version>
</dependency>
It has user friendly interface that you are require if I understood you correctly like this
JSONObject obj = new JSONObject("jsoncontent");
JSONArray arr = obj.getJSONArray("arraykey");
Integer i=obj.getInt("someintegerfield");
JSONObject aob = obj.getJSONObject("anotherobject");
Related
This question already has answers here:
How to parse json parsing Using GSON in android
(5 answers)
Closed 2 years ago.
Context: I'm having trouble getting a value out of a JSON returned by OpenWeatherMap's API via Android.
My JSON looks like this:
{"coord":{"lon":-78.32,"lat":38.55},"weather":[{"id":802,"main":"Clouds","description":"scattered clouds","icon":"03n"}],"base":"stations","main":{"temp":269.05,"feels_like":265.34,"temp_min":267.59,"temp_max":270.37,"pressure":1010,"humidity":78},"visibility":10000,"wind":{"speed":1.25,"deg":293},"clouds":{"all":25},"dt":1607493640,"sys":{"type":3,"id":2006561,"country":"US","sunrise":1607516385,"sunset":1607550737},"timezone":-18000,"id":4744896,"name":"Ashbys Corner","cod":200}
It is stored in a JsonObject (Part of GSON, not to be confused with JSONObject) from a URL like so:
URLConnection requestWeather = weatherUrl.openConnection();
requestWeather.connect(); // connect to the recently opened connection to the OpenWeatherMaps URL
JsonElement parsedJSON = JsonParser.parseReader(new InputStreamReader((InputStream) requestWeather.getContent())); //Convert the input stream of the URL into JSON
JsonObject fetchedJSON = parsedJSON.getAsJsonObject(); // Store the result of the parsed json locally as a json object
Problem: I want to get the value associated with "main" out of the JSON (which in this case should be "Clouds").
Attempted Solution: I've attempted to get the value of main out like this:
String weatherType = fetchedJSON.get("weather").getAsString();
but this throws a java.lang.UnsupportedOperationException: JsonObject exception.
Question: How do I get the value of "main"?
You can use JACKSON or GSON library for fast parsing of Json data using model class.
JACKSON and GSON are dedicated to processing (serializing/deserializing) JSON data.
Raw Parsing via GSON
JsonObject fetchedJSON = parsedJSON.getAsJsonObject();
//weather is an array so get it as array not as string
JsonArray jarray = fetchedJSON.getAsJsonArray("weather");
// OR you use loop if you want all main data
jobject = jarray.get(0).getAsJsonObject();
String main= jobject.get("main").getAsString();
Although if you want raw parsing then you can do like ::
JSONObject obj = new JSONObject(yourString);
JSONArray weather = obj.getJSONArray("weather");
for (int i = 0; i < arr.length(); i++)
{
String main= arr.getJSONObject(i).getString("main");
......
}
I have a goal to verify that certain JSON that I've got from RabbitMQ corresponds to one of expected JSONs in an array in a single file.
In other words, I need to verify that this JSON:
{
"networkCode":"network",
"programId":"92000"
}
is present in this JSON array:
[
{
"networkCode":"network",
"programId":"92000"
},
{
"networkCode":"network",
"programId":"92666"
}
]
Thank you very much for help!
Some part of my code
//GET DESIRABLE JSON
String message = new String(delivery.getBody(), StandardCharsets.UTF_8);
JSONObject myJSON= new JSONObject(message);
//GET THE JSON ARRAYS FROM FILE
JSONParser parser = new JSONParser();
Object expectedJSONs= parser.parse(new FileReader("C:\\amqpclient\\src\\test\\java\\tradeDoubler\\ExpectedDTO.json"));
JSONArray expectedArray = (JSONArray) expectedJSONs;
JSONAssert.assertEquals(
myJSON, expectedArray , JSONCompareMode.LENIENT);
Compilation says that cannot resolve this
Exception in thread "main" java.lang.AssertionError: Expecting a JSON array, but passing in a JSON object
Org.json library is quite easy to use.
Example code below:
import org.json.*;
JSONObject obj = new JSONObject(" yourJSONObjectHere ");
JSONArray arr = obj.getJSONArray("networkArray");
for (int i = 0; i < arr.length(); i++)
{
String networkCode = arr.getJSONObject(i).getString("networkCode");
......
}
By iterating on your JSONArray, you can check if each object is equal to your search.
You may find more examples from: Parse JSON in Java
May I suggest you to use the Gson Library?
You can use something like this. But It will throw an exception if the json doesn't match/contains the fields.
Type listType = new TypeToken<ArrayList<YourJavaClassJsonModel>>() {
}.getType();
List<YourJavaClassJsonModel> resultList = gson.fromJson(JsonString, listType);
Hope it may help
You could use a JSON parser to convert the JSON to a Java object (Jackson and GSON are good options), and then check that object.
I am writing a java code in which i need to convert a JSONObject to JsonElement.Is there any way using which i can convert a JSONObject (org.json) to JsonElement(com.google.gson)?
One way that always works is to serialize the object to JSON and then parse it again:
JSONObject myData = ...
Gson gson = new Gson();
JsonElement element = gson.fromJson(myData.toString(), JsonElement.class);
This is probably a quick answer to a very novice question. I am having trouble wrapping my head around how to get JSON text dbpedia extraction server running from a localhost. The server is running fine, I followed the official instructions.
I have read the other StackOverflow questions about parsing JSON in java and what I am having trouble understanding is how to parse the JSON when the schema or structure is unknown.
For example in my code I try to grab the JSON from localhost and put it into a java object. But all the examples of parsing JSON online use a predesigned java object and all the JSON keys are mapped to an object's fields. (ie Employee class: name,job,email,id,phone)
String sURL = "http://localhost:9999/server/extraction/en/extract?title=" + wikipage + "&revid=&format=rdf-json&extractors=custom"; //just a string
URL url = new URL(sURL);
Reader pageReader = new InputStreamReader(url.openConnection().getInputStream());
Gson g = new Gson();
JsonReader jr = new JsonReader(new InputStreamReader((InputStream) request.getContent()));
jr.setLenient(true);
JsonParser jp = new JsonParser();
JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent())); //convert the input stream to a json element
JsonObject rootobj = root.getAsJsonObject(); //may be an array, may be an object.
I now have this "json object" for the film "Blue Velvet" I can parse/iterate with jr.hasNext() or rootobj.getAsJsonArray().
Am I going about this correctly?
I feel like I am reinventing the wheel. Is there a standard way of parsing DBpedia JSON objects in Java?
At least the Jackson JSON library allows you to parse incoming JSON into a Map. If the keys and values of the JSON can be of any type, then you need to use Map<Object, Object>, which is a bit cumbersome, but anyways this should work:
ObjectMapper mapper = new ObjectMapper();
Map<Object, Object> parsedJSON = mapper.readValue(incomingJSON,
mapper.getTypeFactory().constructMapType(
LinkedHashMap.class,
Object.class,
Object.class));
When I use JSONArray and JSONObject to generate a JSON, whole JSON will be generated in one line. How can I have each record on a separate line?
It generates like this:
[{"key1":"value1","key2":"value2"}]
I need it to be like following:
[{
"key1":"value1",
"key2":"value2"
}]
You can use Pretty Print JSON Output (Jackson).
Bellow are some examples
Convert Object and print its output in JSON format.
User user = new User();
//...set user data
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(user));
Pretty Print JSON String
String test = "{\"age\":29,\"messages\":[\"msg 1\",\"msg 2\",\"msg 3\"],\"name\":\"myname\"}";
Object json = mapper.readValue(test, Object.class);
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(json));
Reference : http://www.mkyong.com/java/how-to-enable-pretty-print-json-output-jackson/
You may use of the google-gson library for beautifying your JSON string.
You can download the library from here
Sample code :
Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonParser jp = new JsonParser();
JsonElement je = jp.parse(uglyJSONString);
String prettyJsonString = gson.toJson(je);
OR
you can use org.json
Sample code :
JSONTokener tokener = new JSONTokener(uglyJsonString); //tokenize the ugly JSON string
JSONObject finalResult = new JSONObject(tokener); // convert it to JSON object
System.out.println(finalResult.toString(4)); // To string method prints it with specified indentation.
Refer answer from this post :
Pretty-Print JSON in Java
The JSON.stringify method supported by many modern browsers (including IE8) can output a beautified JSON string:
JSON.stringify(jsObj, null, "\t"); // stringify with tabs inserted at each level
JSON.stringify(jsObj, null, 4); // stringify with 4 spaces at each level
and please refer this : https://stackoverflow.com/a/2614874/3164682
you can also beautify your string online here.. http://codebeautify.org/jsonviewer
For gettting a easy to read json file you can configure the ObjectMapper to Indent using the following:
objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);