Pretty-Print JSON in Java

Question

I m using json-simple and I need to pretty-print JSON data  make it more human readable    I haven t been able to find this functionality within that library  How is this commonly achieved

User · Answer

If you are using a Java API for JSON Processing (JSR-353) implementation then you can specify the JsonGenerator.PRETTY_PRINTING property when you create a JsonGeneratorFactory.

The following example has been originally published on my blog post.

import java.util.*;
import javax.json.Json;
import javax.json.stream.*;

Map<String, Object> properties = new HashMap<String, Object>(1);
properties.put(JsonGenerator.PRETTY_PRINTING, true);
JsonGeneratorFactory jgf = Json.createGeneratorFactory(properties);
JsonGenerator jg = jgf.createGenerator(System.out);

jg.writeStartObject()                    // {
    .write("name", "Jane Doe")           //    "name":"Jane Doe",
    .writeStartObject("address")         //    "address":{
        .write("type", 1)                //        "type":1,
        .write("street", "1 A Street")   //        "street":"1 A Street",
        .writeNull("city")               //        "city":null,
        .write("verified", false)        //        "verified":false
    .writeEnd()                          //    },
    .writeStartArray("phone-numbers")    //    "phone-numbers":[
        .writeStartObject()              //        {
            .write("number", "555-1111") //            "number":"555-1111",
            .write("extension", "123")   //            "extension":"123"
        .writeEnd()                      //        },
        .writeStartObject()              //        {
            .write("number", "555-2222") //            "number":"555-2222",
            .writeNull("extension")      //            "extension":null
        .writeEnd()                      //        }
    .writeEnd()                          //    ]
.writeEnd()                              // }
.close();

User · Answer

GSON can do this in a nice way   Gson gson   new GsonBuilder   setPrettyPrinting   create    JsonParser jp   new JsonParser    JsonElement je   jp parse uglyJSONString   String prettyJsonString   gson toJson je

User · Answer

My situation is my project uses a legacy  non-JSR  JSON parser that does not support pretty printing  However  I needed to produce pretty-printed JSON samples  this is possible without having to add any extra libraries as long as you are using Java 7 and above   ScriptEngineManager manager   new ScriptEngineManager    ScriptEngine scriptEngine   manager getEngineByName  JavaScript    scriptEngine put  jsonString   jsonStringNoWhitespace   scriptEngine eval  result   JSON stringify JSON parse jsonString   null  2     String prettyPrintedJson    String  scriptEngine get  result

User · Answer

You can use Gson like below  Gson gson   new GsonBuilder   setPrettyPrinting   create    String jsonString   gson toJson object     From the post JSON pretty print using Gson  Alternatively  You can use Jackson like below  ObjectMapper mapper   new ObjectMapper    String perttyStr   mapper writerWithDefaultPrettyPrinter   writeValueAsString object     From the post Pretty print JSON in Java  Jackson   Hope this help

User · Answer

Update   new JsonParser   parse      is  deprecated  Based on the javadoc for Gson 2 8 6   No need to instantiate this class  use the static methods instead   JsonParser static methods  JsonParser parseString  jsonString   JsonParser parseReader  reader     Packages  import com google gson Gson  import com google gson GsonBuilder  import com google gson JsonParser   Example  private Gson GSON   new GsonBuilder   setPrettyPrinting   create    public static String getPerfectJSON String unformattedJSON        String perfectJSON   GSON toJson JsonParser parseString unformattedJSON        return perfectJSON      Google Gson dependency using Maven   lt dependency gt       lt groupId gt com google code gson lt  groupId gt       lt artifactId gt gson lt  artifactId gt       lt version gt 2 8 6 lt  version gt   lt  dependency gt    Reference   JsonParser is deprecated

User · Answer

Following the JSON-P 1 0 specs  JSR-353  a more current solution for a given JsonStructure  JsonObject or JsonArray  could look like this   import java io StringWriter  import java util HashMap  import java util Map   import javax json Json  import javax json JsonStructure  import javax json JsonWriter  import javax json JsonWriterFactory  import javax json stream JsonGenerator   public class PrettyJson        private static JsonWriterFactory FACTORY INSTANCE       public static String toString final JsonStructure status             final StringWriter stringWriter   new StringWriter             final JsonWriter jsonWriter   getPrettyJsonWriterFactory                    createWriter stringWriter            jsonWriter write status           jsonWriter close             return stringWriter toString               private static JsonWriterFactory getPrettyJsonWriterFactory             if  null    FACTORY INSTANCE                final Map lt String  Object gt  properties   new HashMap lt  gt  1               properties put JsonGenerator PRETTY PRINTING  true               FACTORY INSTANCE   Json createWriterFactory properties                     return FACTORY INSTANCE

User · Answer

Pretty printing with GSON in one line   System out println new GsonBuilder   setPrettyPrinting   create   toJson new JsonParser   parse jsonString       Besides inlining  this is equivalent to the accepted answer

User · Answer

In one line   String niceFormattedJson   JsonWriter formatJson jsonString    The json-io libray  https   github com jdereg json-io  is a small  75K  library with no other dependencies than the JDK     In addition to pretty-printing JSON  you can serialize Java objects  entire Java object graphs with cycles  to JSON  as well as read them in

User · Answer

This worked for me  using Jackson   mapper writerWithDefaultPrettyPrinter   writeValueAsString JSONString

User · Answer

With Jackson  com fasterxml jackson databind    ObjectMapper mapper   new ObjectMapper    System out println mapper writerWithDefaultPrettyPrinter   writeValueAsString jsonObject     From  How to enable pretty print JSON output  Jackson   I know this is already in the answers  but I want to write it separately here because chances are  you already have Jackson as a dependency and so all you will need would be an extra line of code

User · Answer

In JSONLib you can use this   String jsonTxt   JSONUtils valueToString json  8  4     From the Javadoc

User · Answer

Most of the existing answers either depend on some external library  or requiring a special Java version  Here is a simple code to pretty print a JSON string  only using general Java APIs  available in Java 7 for higher  haven t tried older version although    The basic idea is to tigger the formatting based on special characters in JSON  For example  if a     or     is observed  the code will create a new line and increase the indent level   Disclaimer  I only tested this for some simple JSON cases  basic key-value pair  list  nested JSON  so it may need some work for more general JSON text  like string value with quotes inside  or special characters   n   t etc            A simple implementation to pretty-print JSON file         param unformattedJsonString     return     public static String prettyPrintJSON String unformattedJsonString      StringBuilder prettyJSONBuilder   new StringBuilder      int indentLevel   0    boolean inQuote   false    for char charFromUnformattedJson   unformattedJsonString toCharArray          switch charFromUnformattedJson          case                 switch the quoting status         inQuote    inQuote          prettyJSONBuilder append charFromUnformattedJson           break        case                 For space  ignore the space if it is not being quoted          if inQuote              prettyJSONBuilder append charFromUnformattedJson                     break        case            case                 Starting a new block  increase the indent level         prettyJSONBuilder append charFromUnformattedJson           indentLevel            appendIndentedNewLine indentLevel  prettyJSONBuilder           break        case            case                 Ending a new block  decrese the indent level         indentLevel--          appendIndentedNewLine indentLevel  prettyJSONBuilder           prettyJSONBuilder append charFromUnformattedJson           break        case                 Ending a json item  create a new line after         prettyJSONBuilder append charFromUnformattedJson           if  inQuote              appendIndentedNewLine indentLevel  prettyJSONBuilder                     break        default          prettyJSONBuilder append charFromUnformattedJson               return prettyJSONBuilder toString              Print a new line with indention at the beginning of the new line      param indentLevel     param stringBuilder     private static void appendIndentedNewLine int indentLevel  StringBuilder stringBuilder      stringBuilder append   n      for int i   0  i  lt  indentLevel  i             Assuming indention using 2 spaces     stringBuilder append

User · Answer

Using org json  Reference link  JSONObject jsonObject   new JSONObject obj   String prettyJson   jsonObject toString 4     Using Gson  Reference link  Gson gson   new GsonBuilder   setPrettyPrinting   create    String json   gson toJson obj     Using Jackson  Reference link  ObjectMapper mapper   new ObjectMapper    mapper enable SerializationFeature INDENT OUTPUT   String json   mapper writeValueAsString obj     Using Genson  Reference link   Genson prettyGenson   new GensonBuilder   useIndentation true  create    String prettyJson   prettyGenson serialize obj

User · Answer

I used org json built-in methods to pretty-print the data   JSONObject json   new JSONObject jsonString      Convert text to object System out println json toString 4       Print it with specified indentation   The order of fields in JSON is random per definition  A specific order is subject to parser implementation

User · Answer

It seems like GSON supports this  although I don t know if you want to switch from the library you are using   From the user guide   Gson gson   new GsonBuilder   setPrettyPrinting   create    String jsonOutput   gson toJson someObject

User · Answer

You can use small json library   String jsonstring         JsonValue json   JsonParser parse jsonstring   String jsonIndendedByTwoSpaces   json toPrettyString

User · Answer

Underscore-java has static method U formatJson json   Five format types are supported  2  3  4  tabs and compact  I am the maintainer of the project  Live example  import com github underscore lodash U   import static com github underscore lodash Json JsonStringBuilder Step TABS  import static com github underscore lodash Json JsonStringBuilder Step TWO SPACES   public class MyClass        public static void main String args              String json       Price                        LineItems                            LineItem                                UnitOfMeasure      EACH      Quantity    2    ItemID      ItemID                                                              Currency      USD                      EnterpriseCode      EnterpriseCode                            System out println U formatJson json  TWO SPACES             System out println U formatJson json  TABS               Output        Price          LineItems            LineItem              UnitOfMeasure    EACH            Quantity   2           ItemID    ItemID                      Currency    USD        EnterpriseCode    EnterpriseCode               Price              LineItems                  LineItem                      UnitOfMeasure    EACH                    Quantity   2                   ItemID    ItemID                                    Currency    USD            EnterpriseCode    EnterpriseCode

User · Answer

Now this can be achieved with the JSONLib library   http   json-lib sourceforge net apidocs net sf json JSONObject html  If  and only if  you use the overloaded toString int indentationFactor  method and not the standard toString   method   I have verified this on the following version of the API    lt dependency gt     lt groupId gt org json lt  groupId gt     lt artifactId gt json lt  artifactId gt     lt version gt 20140107 lt  version gt   lt  dependency gt

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