How to convert POJO to JSON and vice versa

Question

I want to know if there is any Java API available to convert a POJO object to a JSON object and vice versa

User · Answer

Use GSON  for converting POJO to JSONObject  Refer here   For converting JSONObject to POJO  just call the setter method in the POJO and assign the values directly from the JSONObject

User · Answer

If you are aware of Jackson 2  there is a great tutorial at mkyong com on how to convert Java Objects to JSON and vice versa  The following code snippets have been taken from that tutorial   Convert Java object to JSON  writeValue        ObjectMapper mapper   new ObjectMapper    Staff obj   new Staff       Object to JSON in file mapper writeValue new File  c   file json    obj      Object to JSON in String String jsonInString   mapper writeValueAsString obj     Convert JSON to Java object  readValue        ObjectMapper mapper   new ObjectMapper    String jsonInString      name     mkyong        JSON from file to Object Staff obj   mapper readValue new File  c   file json    Staff class      JSON from URL to Object Staff obj   mapper readValue new URL  http   mkyong com api staff json    Staff class      JSON from String to Object Staff obj   mapper readValue jsonInString  Staff class     Jackson 2 Dependency    lt dependency gt       lt groupId gt com fasterxml jackson core lt  groupId gt       lt artifactId gt jackson-databind lt  artifactId gt       lt version gt 2 6 3 lt  version gt   lt  dependency gt    For the full tutorial  please go to the link given above

User · Answer

Take below reference to convert a JSON into POJO and vice-versa Let s suppose your JSON schema looks like       quot type quot   quot object quot      quot properties quot          quot dataOne quot            quot type quot    quot string quot              quot dataTwo quot            quot type quot    quot integer quot              quot dataThree quot            quot type quot    quot boolean quot               Then to covert into POJO  your need to decleare some classes as explained in below style                                     package   public class DataOne       private String type       public void setType String type           this type   type            public String getType            return this type                                              package   public class DataTwo       private String type       public void setType String type           this type   type            public String getType            return this type                                              package   public class DataThree       private String type       public void setType String type           this type   type            public String getType            return this type                                              package   public class Properties       private DataOne dataOne       private DataTwo dataTwo       private DataThree dataThree       public void setDataOne DataOne dataOne           this dataOne   dataOne            public DataOne getDataOne            return this dataOne            public void setDataTwo DataTwo dataTwo           this dataTwo   dataTwo            public DataTwo getDataTwo            return this dataTwo            public void setDataThree DataThree dataThree           this dataThree   dataThree            public DataThree getDataThree            return this dataThree                                              package   public class Root       private String type       private Properties properties       public void setType String type           this type   type            public String getType            return this type            public void setProperties Properties properties           this properties   properties            public Properties getProperties            return this properties

User · Answer

We can also make use of below given dependency and plugin in your pom file - I make use of maven  With the use of these you can generate POJO s as per your JSON Schema and then make use of code given below to populate request JSON object via src object specified as parameter to gson toJson Object src  or vice-versa  Look at the code below   Gson gson   new GsonBuilder   create    String payloadStr   gson toJson data getMerchant   getStakeholder list      Gson gson2   new Gson    Error expectederr   gson2 fromJson payloadStr  Error class     And the Maven settings    lt dependency gt       lt groupId gt com google code gson lt  groupId gt       lt artifactId gt gson lt  artifactId gt       lt version gt 1 7 1 lt  version gt   lt  dependency gt    lt plugin gt       lt groupId gt com googlecode jsonschema2pojo lt  groupId gt       lt artifactId gt jsonschema2pojo-maven-plugin lt  artifactId gt       lt version gt 0 3 7 lt  version gt       lt configuration gt           lt sourceDirectory gt   basedir  src main resources schema lt  sourceDirectory gt           lt targetPackage gt com example types lt  targetPackage gt       lt  configuration gt       lt executions gt           lt execution gt               lt phase gt generate-sources lt  phase gt               lt goals gt                   lt goal gt generate lt  goal gt               lt  goals gt           lt  execution gt       lt  executions gt   lt  plugin gt

User · Answer

You can use jackson api for the conversion   lt dependency gt     lt groupId gt com fasterxml jackson core lt  groupId gt     lt artifactId gt jackson-databind lt  artifactId gt     lt version gt 2 9 4 lt  version gt   lt  dependency gt    add above maven dependency in your POM  In your main method create ObjectMapper   ObjectMapper mapper   new ObjectMapper    mapper enable SerializationFeature INDENT OUTPUT     later we nee to add our POJO class to the mapper  String json   mapper writeValueAsString pojo

User · Answer

Take a look at https   www json org   edited  Imagine that you have a simple Java class like this   public class Person        private String name      private Integer age       public String getName     return this name        public void setName  String name     this name   name         public Integer getAge     return this age        public void setAge  Integer age     this age   age         So  to transform it to a JSon object  it s very simple  Like this   import org json JSONObject   public class JsonTest        public static void main  String   args             Person person   new Person            person setName   Person Name             person setAge  333             JSONObject jsonObj   new JSONObject  person            System out println  jsonObj               Hope it helps    edited  Here there is other example  in this case using Jackson  https   brunozambiazi wordpress com 2015 08 15 working-with-json-in-java   Maven    lt dependency gt       lt groupId gt com fasterxml jackson core lt  groupId gt       lt artifactId gt jackson-databind lt  artifactId gt       lt version gt 2 6 1 lt  version gt   lt  dependency gt    And a link  below  to find the latest greatest version   https   search maven org classic  search 7Cga 7C1 7Cg 3A 22com fasterxml jackson core 22 20AND 20a 3A 22jackson-databind 22

[java] How to convert POJO to JSON and vice versa?

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