Could not read JSON Can not deserialize instance of hello Country out of START OBJECT token

Question

I have rest url that gives me all countries - http   api geonames org countryInfoJSON username volodiaL   I use RestTemplate from spring 3 to parse returned json into java objects   RestTemplate restTemplate   new RestTemplate    Country   countries   restTemplate getForObject  http   api geonames org countryInfoJSON username volodiaL  Country   class     When I run this code I get an exception   Caused by  com fasterxml jackson databind JsonMappingException  Can not deserialize instance of hello Country   out of START OBJECT token  at  Source  sun net www protocol http HttpURLConnection HttpInputStream 1846149  line  1  column  1      at com fasterxml jackson databind JsonMappingException from JsonMappingException java 164      at com fasterxml jackson databind DeserializationContext mappingException DeserializationContext java 691      at com fasterxml jackson databind DeserializationContext mappingException DeserializationContext java 685      at com fasterxml jackson databind deser std ObjectArrayDeserializer handleNonArray ObjectArrayDeserializer java 222      at com fasterxml jackson databind deser std ObjectArrayDeserializer deserialize ObjectArrayDeserializer java 133      at com fasterxml jackson databind deser std ObjectArrayDeserializer deserialize ObjectArrayDeserializer java 18      at com fasterxml jackson databind ObjectMapper  readMapAndClose ObjectMapper java 2993      at com fasterxml jackson databind ObjectMapper readValue ObjectMapper java 2158      at org springframework http converter json MappingJackson2HttpMessageConverter readJavaType MappingJackson2HttpMessageConverter java 225          7 more   Finally my Country class   import com fasterxml jackson annotation JsonIgnoreProperties    JsonIgnoreProperties ignoreUnknown   true  public class Country       private String countryName      private long geonameId       public String getCountryName             return countryName             public long getGeonameId             return geonameId              Override     public String toString             return countryName            The problem is that returned json contains root element  geonames  which contains array of country elements like so      geonames                    continent    EU            capital    Andorra la Vella            languages    ca            geonameId   3041565           south   42 42849259876837           isoAlpha3    AND            north   42 65604389629997           fipsCode    AN            population    84000            east   1 7865427778319827           isoNumeric    020            areaInSqKm    468 0            countryCode    AD            west   1 4071867141112762           countryName    Andorra            continentName    Europe            currencyCode    EUR              How to tell RestTemplate to convert each element of array into Country object

User · Answer

For Spring-boot 1 3 3 the method exchange   for List is working as in the related answer  Spring Data Rest -  links

User · Answer

If you want to avoid using an extra Class and List lt Object gt  genomes you could simply use a Map   The data structure translates into Map lt String  List lt Country gt  gt     String resourceEndpoint    http   api geonames org countryInfoJSON username volodiaL    Map lt String  List lt Country gt  gt  geonames   restTemplate getForObject resourceEndpoint  Map class    List lt Country gt  countries   geonames get  geonames

User · Answer

You need to do the following   public class CountryInfoResponse        JsonProperty  geonames      private List lt Country gt  countries         getter - setter    RestTemplate restTemplate   new RestTemplate    List lt Country gt  countries   restTemplate getForObject  http   api geonames org countryInfoJSON username volodiaL  CountryInfoResponse class  getCountries      It would be great if you could use some kind of annotation to allow you to skip levels  but it s not yet possible  see this and this

User · Answer

In my case  I was getting value of  lt input type  text  gt  with JQuery and I did it like this   var newUserInfo      lastName   inputLastName 0  value   userName   inputUsername 0  value    firstName   inputFirstName 0     email   inputEmail 0  value    And I was constantly getting this exception     com fasterxml jackson databind JsonMappingException  Can not deserialize instance of java lang String out of START OBJECT token    at  Source  java io PushbackInputStream 39cb6c98  line  1  column  54   through reference chain  com springboot domain User  firstName       And I banged my head for like an hour until I realised that I forgot to write  value after this firstName   inputFirstName 0    So  the correct solution was   var newUserInfo      lastName   inputLastName 0  value   userName   inputUsername 0  value    firstName   inputFirstName 0  value    email   inputEmail 0  value    I came here because I had this problem and I hope I save someone else hours of misery   Cheers

User · Answer

Another solution   public class CountryInfoResponse     private List lt Object gt  geonames      Usage of a generic Object-List solved my problem  as there were other Datatypes like Boolean too

[java] Could not read JSON: Can not deserialize instance of hello.Country[] out of START_OBJECT token

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