Convert a JSON String to a HashMap

Question

I m using Java  and I have a String which is JSON      name     abc     email id       abc gmail com   def gmail com   ghi gmail com       Then my Map in Java   Map lt String  Object gt  retMap   new HashMap lt String  Object gt       I want to store all the data from the JSONObject in that HashMap   Can anyone provide code for this   I want to use the org json library

User · Answer

This is an old question and maybe still relate to someone.
Let's say you have string HashMap hash and JsonObject jsonObject.

1) Define key-list.
Example:

ArrayList<String> keyArrayList = new ArrayList<>();  
keyArrayList.add("key0");   
keyArrayList.add("key1");

2) Create foreach loop, add hash from jsonObject with:

for(String key : keyArrayList){  
    hash.put(key, jsonObject.getString(key));
}

That's my approach, hope it answer the question.

User · Answer

You can use Jackson API as well for this        final String json        your json          final ObjectMapper mapper   new ObjectMapper        final MapType type   mapper getTypeFactory   constructMapType          Map class  String class  Object class       final Map lt String  Object gt  data   mapper readValue json  type

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Using Gson  you can do the following  Map lt String  Object gt  retMap   new Gson   fromJson      jsonString  new TypeToken lt HashMap lt String  Object gt  gt       getType

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import java util ArrayList  import java util HashMap  import java util Iterator  import java util List  import java util Map   import org json simple JSONArray  import org json simple JSONObject    public class JsonUtils        public static Map lt String  Object gt  jsonToMap JSONObject json            Map lt String  Object gt  retMap   new HashMap lt String  Object gt              if json    null                retMap   toMap json                     return retMap             public static Map lt String  Object gt  toMap JSONObject object            Map lt String  Object gt  map   new HashMap lt String  Object gt              Iterator lt String gt  keysItr   object keySet   iterator            while keysItr hasNext                  String key   keysItr next                Object value   object get key                if value instanceof JSONArray                    value   toList  JSONArray  value                              else if value instanceof JSONObject                    value   toMap  JSONObject  value                             map put key  value                     return map             public static List lt Object gt  toList JSONArray array            List lt Object gt  list   new ArrayList lt Object gt             for int i   0  i  lt  array size    i                  Object value   array get i               if value instanceof JSONArray                    value   toList  JSONArray  value                              else if value instanceof JSONObject                    value   toMap  JSONObject  value                             list add value                     return list

User · Answer

Convert using Jackson    JSONObject obj   new JSONObject   put  abc    pqr   put  xyz   5    Map lt String  Object gt  map   new ObjectMapper   readValue obj toString    new TypeReference lt Map lt String  Object gt  gt

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I just used Gson HashMap lt String  Object gt  map   new Gson   fromJson json toString    HashMap class

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Imagine u have a list of email like below  not constrained to any programming language   emailsList     abc gmail com   def gmail com   ghi gmail com     Now following is JAVA code - for converting json to map  JSONObject jsonObj   new JSONObject   put  name   abc   put  email id  emailsList   Map lt String  Object gt  s   jsonObj getMap

User · Answer

You can use google gson library to convert json object   https   code google com p google-gson    Other librarys like Jackson are also available   This won t convert it to a map  But you can do all things which you want

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Brief and Useful           param jsonThing can be a  lt code gt JsonObject lt  code gt   a  lt code gt JsonArray lt  code gt                          a  lt code gt Boolean lt  code gt   a  lt code gt Number lt  code gt                          a  lt code gt null lt  code gt  or a  lt code gt JSONObject NULL lt  code gt       return  lt i gt Appropriate Java Object lt  i gt   that may be a  lt code gt Map lt  code gt   a  lt code gt List lt  code gt      a  lt code gt Boolean lt  code gt   a  lt code gt Number lt  code gt  or a  lt code gt null lt  code gt       public static Object jsonThingToAppropriateJavaObject Object jsonThing  throws JSONException       if  jsonThing instanceof JSONArray            final ArrayList lt Object gt  list   new ArrayList lt  gt              final JSONArray jsonArray    JSONArray  jsonThing          final int l   jsonArray length            for  int i   0  i  lt  l    i  list add jsonThingToAppropriateJavaObject jsonArray get i             return list             if  jsonThing instanceof JSONObject            final HashMap lt String  Object gt  map   new HashMap lt  gt              final Iterator lt String gt  keysItr     JSONObject  jsonThing  keys            while  keysItr hasNext                  final String key   keysItr next                map put key  jsonThingToAppropriateJavaObject   JSONObject  jsonThing  get key                       return map             if  JSONObject NULL equals jsonThing   return null       return jsonThing        Thank  Vikas Gupta

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There   s an older answer using javax json posted here  however it only converts JsonArray and JsonObject  but there are still JsonString  JsonNumber  and JsonValue wrapper classes in the output  If you want to get rid of these  here   s my solution which will unwrap everything  Beside that  it makes use of Java 8 streams and is contained in a single method         Convert a JsonValue into a    plain    Java structure  using Map and List           param value The JsonValue  not  lt code gt null lt  code gt       return Map  List  String  Number  Boolean  or  lt code gt null lt  code gt       public static Object toObject JsonValue value        Objects requireNonNull value   quot value was null quot        switch  value getValueType          case ARRAY          return   JsonArray  value                   stream                    map JsonUtils  toObject                   collect Collectors toList         case OBJECT          return   JsonObject  value                   entrySet                    stream                    collect Collectors toMap                          Entry  getKey                          e - gt  toObject e getValue           case STRING          return   JsonString  value  getString        case NUMBER          return   JsonNumber  value  numberValue        case TRUE          return Boolean TRUE      case FALSE          return Boolean FALSE      case NULL          return null      default          throw new IllegalArgumentException  quot Unexpected type   quot    value getValueType

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I wrote this code some days back by recursion   public static Map lt String  Object gt  jsonToMap JSONObject json  throws JSONException       Map lt String  Object gt  retMap   new HashMap lt String  Object gt          if json    JSONObject NULL            retMap   toMap json             return retMap     public static Map lt String  Object gt  toMap JSONObject object  throws JSONException       Map lt String  Object gt  map   new HashMap lt String  Object gt          Iterator lt String gt  keysItr   object keys        while keysItr hasNext              String key   keysItr next            Object value   object get key            if value instanceof JSONArray                value   toList  JSONArray  value                      else if value instanceof JSONObject                value   toMap  JSONObject  value                     map put key  value             return map     public static List lt Object gt  toList JSONArray array  throws JSONException       List lt Object gt  list   new ArrayList lt Object gt         for int i   0  i  lt  array length    i              Object value   array get i           if value instanceof JSONArray                value   toList  JSONArray  value                      else if value instanceof JSONObject                value   toMap  JSONObject  value                     list add value             return list

User · Answer

try this code     Map lt String  String gt  params   new HashMap lt String  String gt                     try                                       Iterator lt   gt  keys   jsonObject keys                         while  keys hasNext                                                  String key    String  keys next                            String value   jsonObject getString key                           params put key  value                                                              catch  Exception xx                                        xx toString

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Here is Vikas s code ported to JSR 353   import java util ArrayList  import java util HashMap  import java util Iterator  import java util List  import java util Map   import javax json JsonArray  import javax json JsonException  import javax json JsonObject   public class JsonUtils       public static Map lt String  Object gt  jsonToMap JsonObject json            Map lt String  Object gt  retMap   new HashMap lt String  Object gt              if json    JsonObject NULL                retMap   toMap json                     return retMap             public static Map lt String  Object gt  toMap JsonObject object  throws JsonException           Map lt String  Object gt  map   new HashMap lt String  Object gt              Iterator lt String gt  keysItr   object keySet   iterator            while keysItr hasNext                  String key   keysItr next                Object value   object get key                if value instanceof JsonArray                    value   toList  JsonArray  value                              else if value instanceof JsonObject                    value   toMap  JsonObject  value                             map put key  value                     return map             public static List lt Object gt  toList JsonArray array            List lt Object gt  list   new ArrayList lt Object gt             for int i   0  i  lt  array size    i                  Object value   array get i               if value instanceof JsonArray                    value   toList  JsonArray  value                              else if value instanceof JsonObject                    value   toMap  JsonObject  value                             list add value                     return list

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Using json-simple you can convert data JSON to Map and Map to JSON   try       JSONObject obj11   new JSONObject        obj11 put 1   Kishan        obj11 put 2   Radhesh        obj11 put 3   Sonal        obj11 put 4   Madhu         Map map   new  HashMap         obj11 toJSONString         map   obj11       System out println map get 1          JSONObject obj12   new JSONObject         obj12    JSONObject  map       System out println obj12 get 1      catch Exception e        System err println  EROR   01    e

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Converting a JSON String to Map  public static Map lt String  Object gt  jsonString2Map  String jsonString   throws JSONException          Map lt String  Object gt  keys   new HashMap lt String  Object gt               org json JSONObject jsonObject   new org json JSONObject  jsonString       HashMap         Iterator lt   gt  keyset   jsonObject keys       HM          while  keyset hasNext                  String key     String  keyset next                Object value   jsonObject get key               System out print   n Key     key               if   value instanceof org json JSONObject                     System out println  Incomin value is of JSONObject                       keys put  key  jsonString2Map  value toString                    else if   value instanceof org json JSONArray                    org json JSONArray jsonArray   jsonObject getJSONArray key                     JSONArray jsonArray   new JSONArray value toString                     keys put  key  jsonArray2List  jsonArray                   else                   keyNode  value                   keys put  key  value                                    return keys          Converting JSON Array to List  public static List lt Object gt  jsonArray2List  JSONArray arrayOFKeys   throws JSONException          System out println  Incoming value is of JSONArray                        List lt Object gt  array2List   new ArrayList lt Object gt             for   int i   0  i  lt  arrayOFKeys length    i                    if   arrayOFKeys opt i  instanceof JSONObject                     Map lt String  Object gt  subObj2Map   jsonString2Map arrayOFKeys opt i  toString                     array2List add subObj2Map                else if   arrayOFKeys opt i  instanceof JSONArray                     List lt Object gt  subarray2List   jsonArray2List  JSONArray  arrayOFKeys opt i                    array2List add subarray2List                else                   keyNode  arrayOFKeys opt i                     array2List add  arrayOFKeys opt i                                     return array2List                Display JSON of Any Format  public static void displayJSONMAP  Map lt String  Object gt  allKeys   throws Exception          Set lt String gt  keyset   allKeys keySet       HM keyset         if    keyset isEmpty                  Iterator lt String gt  keys   keyset iterator       HM keysIterator             while  keys hasNext                      String key   keys next                    Object value   allKeys get  key                    if   value instanceof Map                         System out println   n Object Key     key                           displayJSONMAP jsonString2Map value toString                                          else if   value instanceof List                         System out println   n Array Key     key                       JSONArray jsonArray   new JSONArray value toString                         jsonArray2List jsonArray                    else                       System out println  key     key   value     value                                                         Google gson to HashMap

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The following parser reads a file  parses it into a generic JsonElement  using Google s JsonParser parse method  and then converts all the items in the generated JSON into a native Java List lt object gt  or Map lt String  Object gt    Note  The code below is based off of Vikas Gupta s answer   GsonParser java  import java io FileNotFoundException  import java io InputStreamReader  import java io UnsupportedEncodingException  import java util ArrayList  import java util HashMap  import java util List  import java util Map  import java util Map Entry   import com google gson GsonBuilder  import com google gson JsonArray  import com google gson JsonElement  import com google gson JsonObject  import com google gson JsonParser  import com google gson JsonPrimitive   public class GsonParser       public static void main String   args            try               print loadJsonArray  data array json   true                print loadJsonObject  data object json   true              catch  Exception e                e printStackTrace                         public static void print Object object            System out println new GsonBuilder   setPrettyPrinting   create   toJson object  toString                public static Map lt String  Object gt  loadJsonObject String filename  boolean isResource              throws UnsupportedEncodingException  FileNotFoundException  JsonIOException  JsonSyntaxException  MalformedURLException           return jsonToMap loadJson filename  isResource  getAsJsonObject                public static List lt Object gt  loadJsonArray String filename  boolean isResource              throws UnsupportedEncodingException  FileNotFoundException  JsonIOException  JsonSyntaxException  MalformedURLException           return jsonToList loadJson filename  isResource  getAsJsonArray                private static JsonElement loadJson String filename  boolean isResource  throws UnsupportedEncodingException  FileNotFoundException  JsonIOException  JsonSyntaxException  MalformedURLException           return new JsonParser   parse new InputStreamReader FileLoader openInputStream filename  isResource    UTF-8                public static Object parse JsonElement json            if  json isJsonObject                  return jsonToMap  JsonObject  json             else if  json isJsonArray                  return jsonToList  JsonArray  json                      return null             public static Map lt String  Object gt  jsonToMap JsonObject jsonObject            if  jsonObject isJsonNull                  return new HashMap lt String  Object gt                        return toMap jsonObject              public static List lt Object gt  jsonToList JsonArray jsonArray            if  jsonArray isJsonNull                  return new ArrayList lt Object gt                        return toList jsonArray              private static final Map lt String  Object gt  toMap JsonObject object            Map lt String  Object gt  map   new HashMap lt String  Object gt              for  Entry lt String  JsonElement gt  pair   object entrySet                  map put pair getKey    toValue pair getValue                         return map             private static final List lt Object gt  toList JsonArray array            List lt Object gt  list   new ArrayList lt Object gt              for  JsonElement element   array                list add toValue element                       return list             private static final Object toPrimitive JsonPrimitive value            if  value isBoolean                  return value getAsBoolean              else if  value isString                  return value getAsString              else if  value isNumber                 return value getAsNumber                       return null             private static final Object toValue JsonElement value            if  value isJsonNull                  return null            else if  value isJsonArray                  return toList  JsonArray  value             else if  value isJsonObject                  return toMap  JsonObject  value             else if  value isJsonPrimitive                  return toPrimitive  JsonPrimitive  value                      return null            FileLoader java  import java io File  import java io FileInputStream  import java io FileNotFoundException  import java io IOException  import java io InputStream  import java io InputStreamReader  import java io Reader  import java io UnsupportedEncodingException  import java net MalformedURLException  import java net URISyntaxException  import java net URL  import java util Scanner   public class FileLoader       public static Reader openReader String filename  boolean isResource  throws UnsupportedEncodingException  FileNotFoundException  MalformedURLException           return openReader filename  isResource   UTF-8               public static Reader openReader String filename  boolean isResource  String charset  throws UnsupportedEncodingException  FileNotFoundException  MalformedURLException           return new InputStreamReader openInputStream filename  isResource   charset              public static InputStream openInputStream String filename  boolean isResource  throws FileNotFoundException  MalformedURLException           if  isResource                return FileLoader class getClassLoader   getResourceAsStream filename                      return new FileInputStream load filename  isResource               public static String read String path  boolean isResource  throws IOException           return read path  isResource   UTF-8               public static String read String path  boolean isResource  String charset  throws IOException           return read pathToUrl path  isResource   charset               SuppressWarnings  resource       protected static String read URL url  String charset  throws IOException           return new Scanner url openStream    charset  useDelimiter    A   next               protected static File load String path  boolean isResource  throws MalformedURLException           return load pathToUrl path  isResource               protected static File load URL url            try               return new File url toURI               catch  URISyntaxException e                return new File url getPath                          private static final URL pathToUrl String path  boolean isResource  throws MalformedURLException           if  isResource                return FileLoader class getClassLoader   getResource path                      return new URL  file      path

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If you hate recursion - using a Stack and javax json to convert a Json String into a List of Maps   import java io InputStream  import java util ArrayList  import java util HashMap  import java util List  import java util Map  import java util Stack  import javax json Json  import javax json stream JsonParser   public class TestCreateObjFromJson       public static List lt Map lt String Object gt  gt  extract InputStream is            List extracted   new ArrayList lt  gt             JsonParser parser   Json createParser is            String nextKey               Object nextval               Stack s   new Stack lt  gt             while parser hasNext                  JsonParser Event event   parser next                switch event                    case START ARRAY    List nextList   new ArrayList lt  gt                                         if  s empty                                                 If this is not the root object  add it to tbe parent object                                         setValue s nextKey nextList                                                                             s push nextList                                       break                  case START OBJECT   Map lt String Object gt  nextMap   new HashMap lt  gt                                         if  s empty                                                 If this is not the root object  add it to tbe parent object                                         setValue s nextKey nextMap                                                                             s push nextMap                                       break                  case KEY NAME   nextKey   parser getString                                    break                  case VALUE STRING   setValue s nextKey parser getString                                         break                  case VALUE NUMBER   setValue s nextKey parser getLong                                         break                  case VALUE TRUE     setValue s nextKey true                                       break                  case VALUE FALSE    setValue s nextKey false                                       break                  case VALUE NULL     setValue s nextKey                                          break                  case END OBJECT                      case END ARRAY      if s size    gt  1                                               If this is not a root object  move up                                         s pop                                           else                                              If this is a root object  add ir ro rhw final                                          extracted add s pop                                                            default             break                                   return extracted             private static void setValue Stack s  String nextKey  Object v            if Map class isAssignableFrom s peek   getClass        Map s peek    put nextKey  v           else   List s peek    add v

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Hope this will work  try this   import com fasterxml jackson databind ObjectMapper  Map lt String  Object gt  response   new ObjectMapper   readValue str  HashMap class     str  your JSON String  As Simple as this  if you want emailid    String emailIds   response get  email id   toString

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You can convert any JSON to map by using Jackson library as below   String json      r n  name       abc     r n  email id         abc gmail com     def gmail com     ghi gmail com    r n    ObjectMapper mapper   new ObjectMapper    Map lt String  Object gt  map   new HashMap lt String  Object gt        convert JSON string to Map map   mapper readValue json  new TypeReference lt Map lt String  Object gt  gt         System out println map     Maven Dependencies for Jackson      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 3 lt  version gt       lt scope gt compile lt  scope gt   lt  dependency 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 3 lt  version gt       lt scope gt compile lt  scope gt   lt  dependency gt    Hope this will help  Happy coding

[java] Convert a JSON String to a HashMap

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