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How to parse nested JSON object in java

Here is the sample JSON string. I want to parse this nested JSON object even though nested object have the same name. Some time we may have multiple levels of the nested objects. I tired with Jackson nested objects parsing but that did not work for me. After parsing the object, i want to convert that into a different format.Please help me in parsing this JSON. Thanks in advance.
{
"operator": "and",
"predicates": [
{
"operator": "and",
"predicates": [
{
"columnName": "userName",
"datatype": "string",
"input": "text",
"operand": "equal",
"value": "xxxx"
},
{
"columnName": "Age",
"datatype": "number",
"input": "number",
"operand": "greater_or_equal",
"value": "21"
}
]
},
{
"operator": "and",
"predicates": [
{
"columnName": "userName",
"datatype": "string",
"input": "text",
"operand": "not_equal",
"value": "nnn"
},
{
"columnName": "Birthday",
"datatype": "date",
"input": "date_picker",
"operand": "in",
"value": "2020-07-23,2020-07-24"
}
]
}
]
}
below is the code in java
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonProperty;
public class Predicates {
private String columnName;
private String datatype;
private String input;
private String operator;
private String value;
private String operand;
/**
*
*/
private List<Predicates> predicates;
#JsonProperty("predicates")
private void unpackNested(Map<String,Object> predicates) {
this.columnName = (String)predicates.get("columnName");
this.datatype = (String)predicates.get("datatype");
this.input = (String)predicates.get("input");
this.operator = (String)predicates.get("operator");
this.value = (String)predicates.get("value");
this.operand = (String)predicates.get("operand");
}
public String getColumnName() {
return columnName;
}
public void setColumnName(String columnName) {
this.columnName = columnName;
}
public String getDatatype() {
return datatype;
}
public void setDatatype(String datatype) {
this.datatype = datatype;
}
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
public String getOperator() {
return operator;
}
public void setOperator(String operator) {
this.operator = operator;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
public String getOperand() {
return operand;
}
public void setOperand(String operand) {
this.operand = operand;
}
public List<Predicates> getPredicates() {
return predicates;
}
public void setPredicates(List<Predicates> predicates) {
this.predicates = predicates;
}
}
Parsing
ObjectMapper mapper = new ObjectMapper();
Predicates pr = mapper.readValue(json, Predicates.class);

I don't know what you are trying to achieve with your unpackNested method. Jackson can already bind properties from your JSON to your objects and handles recursive properties just fine.
I simply removed your unpackNested method and ran your code on your provided input:
ObjectMapper mapper = new ObjectMapper();
Predicates pr = mapper.readValue(json, Predicates.class);
The object pr contains the full json including the nested child predicates. (I ran the code with jackson databind 2.11.2).
If your properties are not auto-detected, annotate your getters with #JsonProperty:
class Predicate {
// ..snip..
#JsonProperty("input")
public String getInput() {
return input;
}
#JsonProperty("predicates")
public List<Predicates> getPredicates() {
return predicates;
}
}
But apart from that, no extra steps need to be taken. Jackson can already unpack nested objects, just remove your (weird) unpackNested method and let Jackson do its job.

Cannot deserialize instance of `org.json.JSONObject`

I have a basic SpringBoot 2.1.5.RELEASE app. Using Spring Initializer, JPA, embedded Tomcat, Thymeleaf template engine, and package as an executable JAR file with some RestControllers.
In 1 of the controller this is the body I send:
{
"depositHotel": "xxx",
"destinationHotel": "aaa",
"depositHotelAmount": "0.2",
"destinationHotelAmount": "4",
"destinationAddress": [{
"address": "asdf",
"tag": ""
}],
"refundAddress": [{
"address": "pio",
"tag": ""
}]
}
so I create this class to use it as a RequestBody:
public class HotelswitchHotelOrderRequestBody {
public static class Builder {
private String depositHotel;
private String destinationHotel;
private Float depositHotelAmount;
private Float destinationHotelAmount;
private JSONObject destinationAddress;
private JSONObject refundAddress;
public Builder(String depositHotel, String destinationHotel) {
this.depositHotel = depositHotel;
this.destinationHotel = destinationHotel;
}
public Builder withDepositHotelAmount (Float depositHotelAmount) {
this.depositHotelAmount = depositHotelAmount;
return this;
}
public Builder withDestinationHotelAmount (Float destinationHotelAmount) {
this.destinationHotelAmount = destinationHotelAmount;
return this;
}
public Builder toDestinationAddress (JSONObject destinationAddress) {
this.destinationAddress = destinationAddress;
return this;
}
public Builder toRefundAddress (JSONObject refundAddress) {
this.refundAddress = refundAddress;
return this;
}
public HotelswitchHotelOrderRequestBody build(){
HotelswitchHotelOrderRequestBody order = new HotelswitchHotelOrderRequestBody();
order.depositHotel = this.depositHotel;
order.depositHotelAmount = this.depositHotelAmount;
order.destinationAddress = this.destinationAddress;
order.destinationHotel = this.destinationHotel;
order.destinationHotelAmount = this.destinationHotelAmount;
order.refundAddress = this.refundAddress;
return order;
}
}
private String depositHotel;
private String destinationHotel;
private Float depositHotelAmount;
private Float destinationHotelAmount;
private JSONObject destinationAddress;
private JSONObject refundAddress;
private HotelswitchHotelOrderRequestBody () {
//Constructor is now private.
}
public String getDepositHotel() {
return depositHotel;
}
public void setDepositHotel(String depositHotel) {
this.depositHotel = depositHotel;
}
public String getDestinationHotel() {
return destinationHotel;
}
public void setDestinationHotel(String destinationHotel) {
this.destinationHotel = destinationHotel;
}
public Float getDepositHotelAmount() {
return depositHotelAmount;
}
public void setDepositHotelAmount(Float depositHotelAmount) {
this.depositHotelAmount = depositHotelAmount;
}
public Float getDestinationHotelAmount() {
return destinationHotelAmount;
}
public void setDestinationHotelAmount(Float destinationHotelAmount) {
this.destinationHotelAmount = destinationHotelAmount;
}
public JSONObject getDestinationAddress() {
return destinationAddress;
}
public void setDestinationAddress(JSONObject destinationAddress) {
this.destinationAddress = destinationAddress;
}
public JSONObject getRefundAddress() {
return refundAddress;
}
public void setRefundAddress(JSONObject refundAddress) {
this.refundAddress = refundAddress;
}
}
But I have this error when receiving the object:
JSON parse error: out of START_ARRAY token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `org.json.JSONObject` out of START_ARRAY token

JSONObject's representation in actual JSON is a hash i.e. {...}. In your json data you're providing an array of hashes [{...}] which is not the same. Judging from your domain I don't think it has to be multiple values, so you can just omit [] in your payload and if it does then the fields in your Java class can be defined as JSONArray.
However, I think you should go with defining an Address class and either using
private Address destinationAddress;
private Address refundAddress;
or if it indeed does have to be an object array
private List<Address> destinationAddresses;
private List<Address> refundAddresses;

I had a similar usecase , where I could not define the json to a POJO. Using com.fasterxml.jackson.databind.JsonNode instead of the JSONObject worked.

Jackson Returns empty object

I'm new to Jackson. I've tried to parse Json string to an object but jackson returns an object with all null values. Here is code of my parser:
ObjectMapper mapper = new ObjectMapper();
FullTextRetrievalResponse object =
mapper.readValue(response.getBody().getObject().toString(),
FullTextRetrievalResponse.class);
Here is my FullTextRetrievalResponse class:
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"coredata",
"scopus-id",
"scopus-eid",
"link",
"originalText"
})
public class FullTextRetrievalResponse {
#JsonProperty("coredata")
private Coredata coredata;
#JsonProperty("scopus-id")
private String scopusId;
#JsonProperty("scopus-eid")
private String scopusEid;
#JsonProperty("link")
private Link_ link;
#JsonProperty("originalText")
private OriginalText originalText;
#JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();
#JsonProperty("coredata")
public Coredata getCoredata() {
return coredata;
}
#JsonProperty("coredata")
public void setCoredata(Coredata coredata) {
this.coredata = coredata;
}
#JsonProperty("scopus-id")
public String getScopusId() {
return scopusId;
}
#JsonProperty("scopus-id")
public void setScopusId(String scopusId) {
this.scopusId = scopusId;
}
#JsonProperty("scopus-eid")
public String getScopusEid() {
return scopusEid;
}
#JsonProperty("scopus-eid")
public void setScopusEid(String scopusEid) {
this.scopusEid = scopusEid;
}
#JsonProperty("link")
public Link_ getLink() {
return link;
}
#JsonProperty("link")
public void setLink(Link_ link) {
this.link = link;
}
#JsonProperty("originalText")
public OriginalText getOriginalText() {
return originalText;
}
#JsonProperty("originalText")
public void setOriginalText(OriginalText originalText) {
this.originalText = originalText;
}
#JsonAnyGetter
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}
#JsonAnySetter
public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);
}
and here is part of JSON:
{
"full-text-retrieval-response": {
"coredata": {
"prism:url": "http://api.elsevier.com/content/article/pii/S1751157716302140",
"dc:identifier": "doi:10.1016/j.joi.2016.11.002",
"eid": "1-s2.0-S1751157716302140",
"prism:doi": "10.1016/j.joi.2016.11.002",
"pii": "S1751-1577(16)30214-0",
"dc:title": "The specific shapes of gender imbalance in scientific authorships: A network approach ",
"prism:publicationName": "Journal of Informetrics",
"prism:aggregationType": "Journal",
"prism:issn": "17511577",
"prism:coverDate": "2017-02-28",
"prism:coverDisplayDate": "February 2017",
"openaccess": "0",
"openaccessArticle": false,
"openaccessType": null,
"openArchiveArticle": false,
"openaccessSponsorName": null,
"openaccessSponsorType": null,
"openaccessUserLicense": null,
"link": [
{
"#rel": "self",
"#href": "http://api.elsevier.com/content/article/pii/S1751157716302140",
"#_fa": "true"
},
{
"#rel": "scidir",
"#href": "http://www.sciencedirect.com/science/article/pii/S1751157716302140",
"#_fa": "true"
}
]
}
}
}

The issue is that in your json object you have the field full-text-retrieval-response wrapping all your object, but in your java classes, the FullTextRetrievalResponse is the root.
I think you have 3 options
Change the json structure (supposing you can do that), removing the full-text-retrieval-response label (https://pastebin.com/MtxXSeDW)
Create a new class having an instance of FullTextRetrievalResponse as a json property:
public class FullTextRetrievalResponseWrapper {
#JsonProperty("full-text-retrieval-response")
private FullTextRetrievalResponse fullTextRetrievalResponse;
//setters and getters
}
And then make the serialization using this new class: mapper.readValue(response.getBody().getObject().toString(),
FullTextRetrievalResponseWrapper .class);
Create a custon json deserializer (http://www.baeldung.com/jackson-deserialization) to convert yourself the json object to your class.
Just another quick tip: if you are defining a field as a json property (#JsonProperty), you do not need to define the #JsonSetter, #JsonGetter or even the #JsonProperty in the setters and getters.

Mapping JSON into POJO using Gson

I have the following JSON to represent the server response for a salt request:
{
"USER":
{
"E_MAIL":"email",
"SALT":"salt"
},
"CODE":"010"
}
And i tried to map it with the following POJO:
public class SaltPOJO {
private String code = null;
private User user = null;
#Override
public String toString() {
return this.user.toString();
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public class User {
private String e_mail = null;
private String salt = null;
#Override
public String toString() {
return this.e_mail + ": " + this.salt;
}
public String getE_mail() {
return e_mail;
}
public void setE_mail(String e_mail) {
this.e_mail = e_mail;
}
public String getSalt() {
return salt;
}
public void setSalt(String salt) {
this.salt = salt;
}
}
}
Now everytime i do this:
Gson gson = new Gson();
SaltPOJO saltPojo = gson.fromJson(json.toString(), SaltPOJO.class);
Log.v("Bla", saltPojo.toString());
The saltPojo.toString() is null. How can i map my JSON into POJO using Gson?
Is the order of my variables important for the Gson mapping?

Is the order of my variables important for the Gson mapping?
No, that's not the case.
How can i map my JSON into POJO using Gson?
It's Case Sensitive and the keys in JSON string should be same as variable names used in POJO class.
You can use #SerializedName annotation to use any variable name as your like.
Sample code:
class SaltPOJO {
#SerializedName("CODE")
private String code = null;
#SerializedName("USER")
private User user = null;
...
class User {
#SerializedName("E_MAIL")
private String e_mail = null;
#SerializedName("SALT")
private String salt = null;

You don't have proper mapping between your getter and setter. If you change your json to something like below, it would work:
{
"user":
{
"email":"email",
"salt":"salt"
},
"code":"010"
}
If you are getting json form third party then unfortunately, you would have to change your pojo or you could use adapter.

JSON data binding with custom logic using Jackson

I have defined JSON response which I want to deserialize into Java Objects. I managed to do it "manually" with the Tree Model but if possible I would like to use Data Binding instead. The problem is that I need some custom logic for some parts.
The JSON looks like this:
{
"resourcedescriptions": [
{
"path": "somePath",
"tag_pagetype": "default",
"tag_bookingcenter": [
"bc_ch",
"bc_de"
],
"resources": [
{
"path": "somePathDe.html",
"lang": "de",
"lastmodified": 1399020442914,
"mimetype": "text/html"
},
{
"path": "somePathEn.html",
"lang": "en",
"lastmodified": 1399907224208,
"mimetype": "text/html"
}
],
"lastmodified": 1399907224208
},
{
"path": "someOtherPath",
"tag_pagetype": "special",
"tag_bookingcenter": [
"bc_ch"
],
"resources": [
{
"path": "someOtherPathDe.html",
"lang": "de",
"lastmodified": 1399020442914,
"mimetype": "text/html"
},
{
"path": "someOtherPathEn.html",
"lang": "en",
"lastmodified": 1399907224208,
"mimetype": "text/html"
}
],
"lastmodified": 1399907224208
}
]
}
My Java Classes would be:
public class ResourceDescription {
private String path;
private LocalDateTime lastModified;
private String chartConfig;
private final List<Tag> tags = new ArrayList<Tag>();
private final List<Resource> resources = new ArrayList<Resource>();
}
public class Resource {
private String lang;
private String path;
private String mimeType;
private LocalDateTime lastModified;
}
public class Tag {
private String namespace;
private String name;
}
First question which I still don't fully understand even with reading many posts here. How do I deserialize this array of Resources from the JSON into my List of the ResourceDescription?
Second and most complex question. The JSON properties prefixed with "tag_" need to be transformed into the Tag class, whereas the the property name represents the namespace and the value (single or array) represent the name. So if the pattern is "namespace:name", the first ResourceDescription would have the following tags:
tag_pagetype:default
tag_bookingcenter:bc_ch
tag_bookingcenter:bc_de
Third the "lastmodified" should be transformed into DateTime from Joda-Time.
Is this even possible with data binding or should I stick to the Tree Model?

How do I deserialize this array of Resources from the JSON into my
List of the ResourceDescription?
You have to create additional root class which contains resourcedescriptions property. For example:
class Root {
private List<ResourceDescription> resourcedescriptions;
public List<ResourceDescription> getResourcedescriptions() {
return resourcedescriptions;
}
public void setResourcedescriptions(List<ResourceDescription> resourcedescriptions) {
this.resourcedescriptions = resourcedescriptions;
}
#Override
public String toString() {
return String.valueOf(resourcedescriptions);
}
}
The JSON properties prefixed with "tag_" need to be transformed into
the Tag class, whereas the the property name represents the namespace
and the value (single or array) represent the name.
You can handle this case using #JsonAnySetter annotation. You have to add new method to ResourceDescription class which could look like this:
#JsonAnySetter
public void setAnyValues(String propertyName, Object value) {
if (propertyName.startsWith("tag_")) {
if (value instanceof String) {
tags.add(new Tag(propertyName, value.toString()));
} else if (value instanceof List) {
List<?> values = (List<?>) value;
for (Object v : values) {
tags.add(new Tag(propertyName, v.toString()));
}
}
// throw exception?
} else {
// handle another unknown properties
}
}
Third the "lastmodified" should be transformed into DateTime from
Joda-Time.
You can handle JodaTime types by adding jackson-datatype-joda library. When you add it you can register JodaModule module.
mapper.registerModule(new JodaModule());
Additional problem that your JSON contain properties written using lowercase, but your POJO properties are written using camel-case. You can change JSON or POJO or use #JsonProperty("property-name-from-JSON") annotation or implement your own naming strategy. For example:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy.PropertyNamingStrategyBase() {
#Override
public String translate(String propertyName) {
return propertyName.toLowerCase();
}
});
Full Java example how to you can deserialize your JSON:
import java.util.ArrayList;
import java.util.List;
import org.joda.time.LocalDateTime;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.datatype.joda.JodaModule;
public class JacksonProgram {
public static void main(String[] args) throws Exception {
String json = "{ ... }";
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JodaModule());
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy.PropertyNamingStrategyBase() {
#Override
public String translate(String propertyName) {
return propertyName.toLowerCase();
}
});
System.out.println(mapper.readValue(json, Root.class));
}
}
class Root {
private List<ResourceDescription> resourcedescriptions;
public List<ResourceDescription> getResourcedescriptions() {
return resourcedescriptions;
}
public void setResourcedescriptions(List<ResourceDescription> resourcedescriptions) {
this.resourcedescriptions = resourcedescriptions;
}
#Override
public String toString() {
return String.valueOf(resourcedescriptions);
}
}
class ResourceDescription {
private String path;
private LocalDateTime lastModified;
private String chartConfig;
private final List<Tag> tags = new ArrayList<Tag>();
private final List<Resource> resources = new ArrayList<Resource>();
#JsonAnySetter
public void setAnyValues(String propertyName, Object value) {
if (propertyName.startsWith("tag_")) {
if (value instanceof String) {
tags.add(new Tag(propertyName, value.toString()));
} else if (value instanceof List) {
List<?> values = (List<?>) value;
for (Object v : values) {
tags.add(new Tag(propertyName, v.toString()));
}
}
// throw exception?
} else {
// handle another unknown properties
}
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public LocalDateTime getLastModified() {
return lastModified;
}
public void setLastModified(LocalDateTime lastModified) {
this.lastModified = lastModified;
}
public String getChartConfig() {
return chartConfig;
}
public void setChartConfig(String chartConfig) {
this.chartConfig = chartConfig;
}
public List<Tag> getTags() {
return tags;
}
public List<Resource> getResources() {
return resources;
}
#Override
public String toString() {
return "ResourceDescription [path=" + path + ", lastModified=" + lastModified
+ ", chartConfig=" + chartConfig + ", tags=" + tags + ", resources=" + resources
+ "]";
}
}
class Resource {
private String lang;
private String path;
private String mimeType;
private LocalDateTime lastModified;
public String getLang() {
return lang;
}
public void setLang(String lang) {
this.lang = lang;
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public String getMimeType() {
return mimeType;
}
public void setMimeType(String mimeType) {
this.mimeType = mimeType;
}
public LocalDateTime getLastModified() {
return lastModified;
}
public void setLastModified(LocalDateTime lastModified) {
this.lastModified = lastModified;
}
#Override
public String toString() {
return "Resource [lang=" + lang + ", path=" + path + ", mimeType=" + mimeType
+ ", lastModified=" + lastModified + "]";
}
}
class Tag {
private String namespace;
private String name;
public Tag() {
}
public Tag(String namespace, String name) {
this.namespace = namespace;
this.name = name;
}
public String getNamespace() {
return namespace;
}
public void setNamespace(String namespace) {
this.namespace = namespace;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Override
public String toString() {
return "Tag [namespace=" + namespace + ", name=" + name + "]";
}
}
Above program prints:
[ResourceDescription [path=somePath, lastModified=2014-05-12T17:07:04.208, chartConfig=null, tags=[Tag [namespace=tag_pagetype, name=default], Tag [namespace=tag_bookingcenter, name=bc_ch], Tag [namespace=tag_bookingcenter, name=bc_de]], resources=[Resource [lang=de, path=somePathDe.html, mimeType=text/html, lastModified=2014-05-02T10:47:22.914], Resource [lang=en, path=somePathEn.html, mimeType=text/html, lastModified=2014-05-12T17:07:04.208]]], ResourceDescription [path=someOtherPath, lastModified=2014-05-12T17:07:04.208, chartConfig=null, tags=[Tag [namespace=tag_pagetype, name=special], Tag [namespace=tag_bookingcenter, name=bc_ch]], resources=[Resource [lang=de, path=someOtherPathDe.html, mimeType=text/html, lastModified=2014-05-02T10:47:22.914], Resource [lang=en, path=someOtherPathEn.html, mimeType=text/html, lastModified=2014-05-12T17:07:04.208]]]]

You will need to create a custom deserializer for ResourceDescription in order to accomplish what you need to do. The syntax for specifying a custom deserializer for ResourceDescription will look like this:
#JsonDeserialize(using=ResourceDescriptionDeserializer.class)
public class ResourceDescription { ... }
This deserializer will have to iterate through each of the keys for each resource description to see if it begins with "tag_", strip off the prefix and use the remaining for the namespace and populate the name/value for the Tag before adding it to the array of the ResourceDescription being created.
For all other attributes/types I think you can just defer to the default deserialization and set those attributes on their respective fields.
Then, to deserialize the list of ResourceDescriptions you can specify a TypeReference to avoid writing a custom deserializer for ResourceDescriptions. The code will look something like this:
Map<String, List<ResourceDescription>> resultMap =
objectMapper.readValue(JSON, new TypeReference<Map<String, List<ResourceDescription>>>() {});
List<ResourceDescription> descriptions = resultMap.get("resourcedescriptions");
Here's an article that doesn't quite pair with what you're doing but I think will help with the general idea:
Using Jackson to deserialize array nested within array in JSON object