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I am trying to get a value from a JSON string but I am getting a null value instead.
App2.java :
package JsonExample1;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.map.ObjectMapper;
import java.io.IOException;
import java.io.StringReader;
public class App2 {
private JsonNode rootNode;
public void setup() throws IOException {
String jsonString = "{\n" +
" \"HotelListResponse\" : {\n" +
" \"customerSessionId\" : \"0ABAAA7A-90C9-7491-3FF2-7E2C37496CA2\",\n" +
" \"numberOfRoomsRequested\" : 1,\n" +
" \"moreResultsAvailable\" : true,\n" +
" \"cacheKey\" : \"7790c974:13ff7e2c374:6ccd\",\n" +
" \"cacheLocation\" : \"10.186.170.122:7300\",\n" +
" \"HotelList\" : {\n" +
" \"@activePropertyCount\" : \"223\",\n" +
" \"@size\" : \"1\",\n" +
" \"HotelSummary\" : {\n" +
" \"@order\" : \"0\",\n" +
" \"hotelId\" : 125727,\n" +
" \"name\" : \"Red Lion Hotel on Fifth Avenue\",\n" +
" \"address1\" : \"1415 5th Ave\",\n" +
" \"city\" : \"Seattle\",\n" +
" \"stateProvinceCode\" : \"WA\",\n" +
" \"postalCode\" : 98101,\n" +
" \"countryCode\" : \"US\",\n" +
" \"airportCode\" : \"SEA\",\n" +
" \"supplierType\" : \"E\",\n" +
" \"hotelRating\" : 3.5,\n" +
" \"propertyCategory\" : 1,\n" +
" \"confidenceRating\" : 90,\n" +
" \"amenityMask\" : 7847938,\n" +
" \"tripAdvisorRating\" : 4,\n" +
" \"locationDescription\" : \"Near Pike Place Market\",\n" +
" \"shortDescription\" : \"<p><b>Location. </b> <br />Red Lion Hotel on Fifth Avenue is located close to 5th Avenue Theater, Pike Place Market, and Washington State Convention & Trade Center. Additional points of interest\",\n" +
" \"highRate\" : 149,\n" +
" \"lowRate\" : 126.65,\n" +
" \"rateCurrencyCode\" : \"USD\",\n" +
" \"latitude\" : 47.60985,\n" +
" \"longitude\" : -122.33475,\n" +
" \"proximityDistance\" : 11.168453,\n" +
" \"proximityUnit\" : \"MI\",\n" +
" \"hotelInDestination\" : true,\n" +
" \"thumbNailUrl\" : \"/hotels/1000000/60000/51000/50947/50947_180_t.jpg\",\n" +
" \"deepLink\" : \"http://travel.ian.com/index.jsp?pageName=hotAvail&cid=55505&hotelID=125727&mode=2&numberOfRooms=1&room-0-adult-total=2&room-0-child-total=0&arrivalMonth=8&arrivalDay=4&departureMonth=8&departureDay=5&showInfo=true&locale=en_US&currencyCode=USD\",\n" +
" \"RoomRateDetailsList\" : {\n" +
" \"RoomRateDetails\" : {\n" +
" \"roomTypeCode\" : 253461,\n" +
" \"rateCode\" : 201054304,\n" +
" \"maxRoomOccupancy\" : 2,\n" +
" \"quotedRoomOccupancy\" : 2,\n" +
" \"minGuestAge\" : 0,\n" +
" \"roomDescription\" : \"Classic Single Queen\",\n" +
" \"promoId\" : 202161947,\n" +
" \"promoDescription\" : \"Summer Sale! Save 15%\",\n" +
" \"currentAllotment\" : 0,\n" +
" \"propertyAvailable\" : true,\n" +
" \"propertyRestricted\" : false,\n" +
" \"expediaPropertyId\" : 50947,\n" +
" \"rateKey\" : \"0ABAAA7A-90C9-7491-3FF2-7E2C37496CCE\",\n" +
" \"RateInfo\" : {\n" +
" \"@rateChange\" : \"false\",\n" +
" \"@promo\" : \"true\",\n" +
" \"@priceBreakdown\" : \"true\",\n" +
" \"ChargeableRateInfo\" : {\n" +
" \"@total\" : \"151.23\",\n" +
" \"@surchargeTotal\" : \"24.58\",\n" +
" \"@nightlyRateTotal\" : \"126.65\",\n" +
" \"@maxNightlyRate\" : \"126.65\",\n" +
" \"@currencyCode\" : \"USD\",\n" +
" \"@commissionableUsdTotal\" : \"126.65\",\n" +
" \"@averageRate\" : \"126.65\",\n" +
" \"@averageBaseRate\" : \"149.0\",\n" +
" \"NightlyRatesPerRoom\" : {\n" +
" \"@size\" : \"1\",\n" +
" \"NightlyRate\" : {\n" +
" \"@promo\" : \"true\",\n" +
" \"@rate\" : \"126.65\",\n" +
" \"@baseRate\" : \"149.0\"\n" +
" }\n" +
" },\n" +
" \"Surcharges\" : {\n" +
" \"@size\" : \"1\",\n" +
" \"Surcharge\" : {\n" +
" \"@amount\" : \"24.58\",\n" +
" \"@type\" : \"TaxAndServiceFee\"\n" +
" }\n" +
" }\n" +
" }\n" +
" },\n" +
" \"ValueAdds\" : {\n" +
" \"@size\" : \"1\",\n" +
" \"ValueAdd\" : {\n" +
" \"@id\" : \"2048\",\n" +
" \"description\" : \"Free Wireless Internet\"\n" +
" }\n" +
" }\n" +
" }\n" +
" }\n" +
" }\n" +
" }\n" +
" }\n" +
" }";
rootNode = new ObjectMapper().readTree(new StringReader(jsonString));
}
//other methods
public void basicTreeModelRead()
{
//Just like DOM, our data is in a hierarchy of node (in this case, it is JsonNode)
JsonNode aField = rootNode.get("customerSessionId");
//the customerSessionId has a String value
String myString = aField.asText();
System.out.println("customerSessionId is:" + myString);
}
}
StartHere.java:
package JsonExample1;
import java.io.IOException;
public class StartHere {
public static void main(String[] args) {
App2 myApp = new App2();
try {
myApp.setup();
} catch (IOException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
myApp.basicTreeModelRead();
}
}
After debugging I found that aField value remains null. Any ideas?
372
getJsonString() Method It is used to get the (JsonString)get(name). The method parses an argument name of type String whose related value is to be returned. It returns the String value of the associated mapping for the parsed parameter. It returns null if the object has no mapping for the parameter.
Read Object From JSON via URL ObjectMapper objectMapper = new ObjectMapper(); URL url = new URL("file:data/car. json"); Car car = objectMapper. readValue(url, Car. class);
Your root node doesn't have a customerSessionId, it has a HotelListResponse. Get that first.
//other methods
public void basicTreeModelRead()
{
JsonNode innerNode = rootNode.get("HotelListResponse"); // Get the only element in the root node
// get an element in that node
JsonNode aField = innerNode.get("customerSessionId");
//the customerSessionId has a String value
String myString = aField.asText();
System.out.println("customerSessionId is:" + myString);
}
This prints
customerSessionId is:0ABAAA7A-90C9-7491-3FF2-7E2C37496CA2
Another way to get the inner element, with .at() method:
rootNode.at("/HotelListResponse/customerSessionId")
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