How to convert List to Json in Java

Question

How to convert generic list to json in Java I have class like this    public class Output       public int Keyname   get  set        public Object  outputvalue  get  set       outvalue may be even a object collection    List lt Output gt  outputList   new List lt Output gt       I want to convert outputList  into json in Java After converting i will send it to client

User · Answer

For simplicity and well structured sake  use SpringMVC  It s just so simple    RequestMapping   carlist json   public  ResponseBody List lt String gt  getCarList         return carService getAllCars        Reference and credit  https   github com xvitcoder spring-mvc-angularjs

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Look at the google gson library   It provides a rich api for dealing with this and is very straightforward to use

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Use GSONBuilder with setPrettyPrinting and disableHtml for nice output    String json   new GsonBuilder   setPrettyPrinting   disableHtmlEscaping                                create   toJson outputList                         fileOut println json

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Try this   public void test       net sf json JSONObject  net sf json JSONArray      List objList   new ArrayList    objList add  obj1    objList add  obj2    objList add  obj3    HashMap objMap   new HashMap    objMap put  key1    value1    objMap put  key2    value2    objMap put  key3    value3    System out println  JSONArray       JSONArray JSONSerializer toJSON objList    System out println  JSONObject       JSONObject JSONSerializer toJSON objMap        you can find API here

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You need an external library for this   JSONArray jsonA   JSONArray fromObject mybeanList   System out println jsonA     Google GSON is one of such libraries   You can also take a look here for examples on converting Java object collection to JSON string

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Use GSON library for that  Here is the sample code  List lt String gt  foo   new ArrayList lt String gt     foo add  A    foo add  B    foo add  C     String json   new Gson   toJson foo      Here is the maven dependency for Gson   lt dependencies gt       lt  --  Gson  Java to Json conversion -- gt       lt dependency gt           lt groupId gt com google code gson lt  groupId gt           lt artifactId gt gson lt  artifactId gt           lt version gt 2 2 2 lt  version gt           lt scope gt compile lt  scope gt       lt  dependency gt   lt  dependencies gt    Or you can directly download jar from here and put it in your class path  http   code google com p google-gson downloads detail name gson-1 0 jar amp can 4 amp q   To send Json to client you can use spring or in simple servlet add this code     response getWriter   write json

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jackson provides very helpful and lightweight API to convert Object to JSON and vise versa  Please find the example code below to perform the operation  List lt Output gt  outputList   new ArrayList lt Output gt     public static void main String   args        try           Output output   new Output 1  2342            ObjectMapper objectMapper   new ObjectMapper            String jsonString   objectMapper writeValueAsString output           System out println jsonString         catch  JsonProcessingException e            e printStackTrace              there are many other features and nice documentation for Jackson API  you can refer to the links like  https   www journaldev com 2324 jackson-json-java-parser-api-example-tutorial    dependencies to include in the project are        lt  -- Jackson -- gt       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 5 1 lt  version gt       lt  dependency gt       lt dependency gt           lt groupId gt com fasterxml jackson core lt  groupId gt           lt artifactId gt jackson-core lt  artifactId gt           lt version gt 2 5 1 lt  version gt       lt  dependency gt       lt dependency gt           lt groupId gt com fasterxml jackson core lt  groupId gt           lt artifactId gt jackson-annotations lt  artifactId gt           lt version gt 2 5 1 lt  version gt       lt  dependency gt

User · Answer

download java-json jar from Java2s  then use the JSONArray constructor  List myList   new ArrayList lt  gt         JSONArray jsonArray   new JSONArray myList   System out println jsonArray

[java] How to convert List to Json in Java

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