JSON - Iterate through JSONArray

Question

I have a JSON file with some arrays in it  I want to iterate through the file arrays and get their elements and their values   This is how my file looks like      JObjects          JArray1                            A    a                B    b                C    c                                    A    a1                B    b2                C    c3                D    d4               E    e5                                    A    aa                B    bb                C    cc                D    dd                                 This is how far I have come   JSONObject object   new JSONObject  json-file json    JSONObject getObject   object getJSONObject  JObjects    JSONArray getArray   getObject getJSONArray  JArray1     for int i   0  i  lt  getArray size    i            JSONObject objects   getArray getJSONArray i           Iterate through the elements of the array i          Get thier value          Get the value for the first element and the value for the last element      Is it possible to do something like this   The reason I want to do it like this is because the arrays in the file have a different number of elements

User · Answer

for  int i   0  i  lt  getArray length    i                  JSONObject objects   getArray getJSONObject i               Iterator key   objects keys                while  key hasNext                      String k   key next   toString                    System out println  Key       k      value                               objects getString k                                 System out println objects toString                 System out println  -----------                 Hope this helps someone

User · Answer

JsonArray jsonArray  Iterator lt JsonElement gt  it   jsonArray iterator    while it hasNext         System out println it next

User · Answer

You could try my   heavily borrowed from various sites  recursive method to go through all JSON objects and JSON arrays until you find JSON elements   This example actually searches for a particular key and returns all values for all instances of that key    searchKey  is the key you are looking for   ArrayList lt String gt  myList   new ArrayList lt String gt     myList   findMyKeyValue yourJsonPayload null  A      if you only wanted to search for A s values      private ArrayList lt String gt  findMyKeyValue JsonElement element  String key  String searchKey           OBJECT     if element isJsonObject              JsonObject jsonObject   element getAsJsonObject               loop through all elements in object          for  Map Entry lt String JsonElement gt  entry   jsonObject entrySet                  JsonElement array   entry getValue                findMyKeyValue array  entry getKey    searchKey                     ARRAY       else if element isJsonArray                when an array is found keep  key  as that is the array s name i e  pass it down          JsonArray jsonArray   element getAsJsonArray               loop through all elements in array         for  JsonElement childElement   jsonArray                findMyKeyValue childElement  key  searchKey                    NEITHER       else              System out println  SKey      searchKey     Key      key                 if  key equals searchKey                    listOfValues add element getAsString                             return listOfValues

User · Answer

Change  JSONObject objects   getArray getJSONArray i     to  JSONObject objects   getArray getJSONObject i     or to  JSONObject objects   getArray optJSONObject i     depending on which JSON-to from-Java library you re using    It looks like getJSONObject will work for you    Then  to access the string elements in the  objects  JSONObject  get them out by element name   String a   objects get  A      If you need the names of the elements in the JSONObject  you can use the static utility method JSONObject getNames JSONObject  to do so   String   elementNames   JSONObject getNames objects         Get the value for the first element and the value for the last element     If  element  is referring to the component in the array  note that the first component is at index 0  and the last component is at index getArray length   - 1        I want to iterate though the objects in the array and get thier component and thier value  In my example the first object has 3 components  the scond has 5 and the third has 4 components  I want iterate though each of them and get thier component name and value    The following code does exactly that   import org json JSONArray  import org json JSONObject   public class Foo     public static void main String   args  throws Exception         String jsonInput       JObjects      JArray1       A     a     B     b     C     c       A     a1     B     b2     C     c3     D     d4     E     e5       A     aa     B     bb     C     cc     D     dd                  I want to iterate though the objects in the array         JSONObject outerObject   new JSONObject jsonInput       JSONObject innerObject   outerObject getJSONObject  JObjects        JSONArray jsonArray   innerObject getJSONArray  JArray1        for  int i   0  size   jsonArray length    i  lt  size  i                JSONObject objectInArray   jsonArray getJSONObject i                 and get thier component and thier value         String   elementNames   JSONObject getNames objectInArray         System out printf   d ELEMENTS IN CURRENT OBJECT  n   elementNames length         for  String elementName   elementNames                  String value   objectInArray getString elementName           System out printf  name  s  value  s n   elementName  value                 System out println                   OUTPUT  3 ELEMENTS IN CURRENT OBJECT  name A  value a name B  value b name C  value c  5 ELEMENTS IN CURRENT OBJECT  name D  value d4 name E  value e5 name A  value a1 name B  value b2 name C  value c3  4 ELEMENTS IN CURRENT OBJECT  name D  value dd name A  value aa name B  value bb name C  value cc

User · Answer

for int i   0  i  lt  getArray size    i           Object object   getArray get i            now do something with the Object     You need to check for the type      The values can be any of these types  Boolean  JSONArray  JSONObject    Number  String  or the JSONObject NULL object   Source    In your case  the elements will be of type JSONObject  so you need to cast to JSONObject and call JSONObject names   to retrieve the individual keys

[java] JSON - Iterate through JSONArray

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