Pretty printing JSON from Jackson 2 2 s ObjectMapper

Question

Right now I have an instance of org fasterxml jackson databind ObjectMapper and would like to get a String with pretty JSON  All of the results of my Google searches have come up with Jackson 1 x ways of doing this and I can t seem to find the proper  non-deprecated way of doing this with 2 2  Even though I don t believe that code is absolutely necessary for this question  here s what I have right now   ObjectMapper mapper   new ObjectMapper    mapper setSerializationInclusion Include NON NULL   System out println   n n----------REQUEST-----------    StringWriter sw   new StringWriter    mapper writeValue sw  jsonObject      Want pretty version of sw toString   here

User · Answer

According to mkyong  the magic incantation is defaultPrintingWriter to pretty print JSON   Newer versions   System out println mapper writerWithDefaultPrettyPrinter   writeValueAsString jsonInstance      Older versions   System out println mapper defaultPrettyPrintingWriter   writeValueAsString jsonInstance        Seems I jumped the gun a tad quickly  You could try gson  whose constructor supports pretty-printing   Gson gson   new GsonBuilder   setPrettyPrinting   create    String jsonOutput   gson toJson someObject     Hope this helps

User · Answer

You can enable pretty-printing by setting the SerializationFeature INDENT OUTPUT on your ObjectMapper like so   mapper enable SerializationFeature INDENT OUTPUT

User · Answer

the IDENT OUTPUT did not do anything for me  and to give a complete answer that works with my jackson 2 2 3 jars   public static void main String   args  throws IOException    byte   jsonBytes   Files readAllBytes Paths get  C   data  testfiles  single-line json      ObjectMapper objectMapper   new ObjectMapper     Object json   objectMapper readValue  jsonBytes  Object class     System out println  objectMapper writerWithDefaultPrettyPrinter   writeValueAsString  json

User · Answer

If others who view this question only have a JSON string  not in an object   then you can put it into a HashMap and still get the ObjectMapper to work  The result variable is your JSON string   import com fasterxml jackson core JsonParseException  import com fasterxml jackson databind JsonMappingException  import com fasterxml jackson databind ObjectMapper  import java util HashMap  import java util Map      Pretty-print the JSON result try       ObjectMapper objectMapper   new ObjectMapper        Map lt String  Object gt  response   objectMapper readValue result  HashMap class       System out println objectMapper writerWithDefaultPrettyPrinter   writeValueAsString response      catch  JsonParseException e        e printStackTrace      catch  JsonMappingException e        e printStackTrace      catch  IOException e        e printStackTrace

User · Answer

If you d like to turn this on by default for ALL ObjectMapper instances in a process  here s a little hack that will set the default value of INDENT OUTPUT to true   val indentOutput   SerializationFeature INDENT OUTPUT val defaultStateField   indentOutput getClass getDeclaredField   defaultState   defaultStateField setAccessible true  defaultStateField set indentOutput  true

User · Answer

if you are using spring and jackson combination you can do it as following  I m following  gregwhitaker as suggested but implementing in spring style                    lt bean id  objectMapper  class  com fasterxml jackson databind ObjectMapper  gt       lt property name  dateFormat  gt           lt bean class  java text SimpleDateFormat  gt               lt constructor-arg value  yyyy-MM-dd    gt               lt property name  lenient  value  false    gt           lt  bean gt       lt  property gt       lt property name  serializationInclusion  gt           lt value type  com fasterxml jackson annotation JsonInclude Include  gt              NON NULL          lt  value gt       lt  property gt   lt  bean gt    lt bean class  org springframework beans factory config MethodInvokingFactoryBean  gt       lt property name  targetObject  gt           lt ref bean  objectMapper    gt       lt  property gt       lt property name  targetMethod  gt           lt value gt enable lt  value gt       lt  property gt       lt property name  arguments  gt           lt value type  com fasterxml jackson databind SerializationFeature  gt              INDENT OUTPUT          lt  value gt       lt  property gt   lt  bean gt

User · Answer

The jackson API has changed   new ObjectMapper    writer    withDefaultPrettyPrinter    writeValueAsString new HashMap lt String  Object gt

User · Answer

Try this    objectMapper enable SerializationConfig Feature INDENT OUTPUT

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