JSON Array iteration in Android Java

Question

I am building an android app that needs to download and synchronise with an online database  I am sending my query from the app to a php page which returns the relevant rows from a database in JSON format    can someone please tell me the best way to iterate through a JSON array   I receive an array of objects     json object   json object   json object    What is the simplest piece of code I could use to access the JSONObjects in the array   EDIT  now that I think of it the method I used to iterate the loop was   for  String row  json        id   row getInt  id         name   row getString  name         password   row getString  password        So I guess I had was somehow able to turn the returned Json into and iterable array  Any Ideas how I could achieve this   I apologise for my vaguness but I had this working from an example I found on the web and have since been unable to find it

User · Answer

On Arrays  look for    JSONArray menuitemArray   popupObject getJSONArray  menuitem

User · Answer

I think this code is short and clear   int id  String name  JSONArray array   new JSONArray string of json array   for  int i   0  i  lt  array length    i          JSONObject row   array getJSONObject i       id   row getInt  id        name   row getString  name        Is that what you were looking for

User · Answer

I have done it two different ways   1   make a Map          HashMap lt String  String gt  applicationSettings   new HashMap lt String String gt             for int i 0  i lt settings length    i                 String value   settings getJSONObject i  getString  value                String name   settings getJSONObject i  getString  name                applicationSettings put name  value               2   make a JSONArray of names      JSONArray names   json names        JSONArray values   json toJSONArray names       for int i 0  i lt values length    i             if  names getString i  equals  description                 setDescription values getString i                      else if  names getString i  equals  expiryDate                 String dateString   values getString i               setExpiryDate stringToDateHelper dateString                       else if  names getString i  equals  id                 setId values getLong i                      else if  names getString i  equals  offerCode                 setOfferCode values getString i                      else if  names getString i  equals  startDate                 String dateString   values getString i               setStartDate stringToDateHelper dateString                      else if  names getString i  equals  title                 setTitle values getString i

User · Answer

While iterating over a JSON array  org json JSONArray  built into Android   watch out for null objects  for example  you may get  null  instead of a null string   A check may look like   s i    array isNull i    null   array getString i

User · Answer

When I tried  vipw s suggestion  I was faced with this exception   The method getJSONObject int  is undefined for the type JSONArray   This worked for me instead   int myJsonArraySize   myJsonArray size     for  int i   0  i  lt  myJsonArraySize  i          JSONObject myJsonObject    JSONObject  myJsonArray get i           Do whatever you have to do to myJsonObject

User · Answer

Unfortunately   JSONArray doesn t support foreach statements  like    x000D   x000D  for JSONObject someObj   someJsonArray    x000D         do something about someObj x000D           x000D           x000D    x000D   x000D   x000D

User · Answer

You are using the same Cast object for every entry  On each iteration you just changed the same object instead creating a new one   This code should fix it   JSONArray jCastArr   jObj getJSONArray  abridged cast    ArrayList lt Cast gt  castList  new ArrayList lt Cast gt      for  int i 0  i  lt  jCastArr length    i          Cast person   new Cast        create a new object here     JSONObject jpersonObj   jCastArr getJSONObject i        person castId    String  jpersonObj getString  id        person castFullName    String  jpersonObj getString  name         castList add person     details castList   castList

User · Answer

If you re using the JSON org Java implementation  which is open source  you can just make JSONArray implement the Iterable interface and add the following method to the class    Override public Iterator iterator         return this myArrayList iterator        This will make all instances of JSONArray iterable  meaning that the for  Object foo   bar  syntax will now work with it  note that foo has to be an Object  because JSONArrays do not have a declared type   All this works because the JSONArray class is backed by a simple ArrayList  which is already iterable  I imagine that other open source implementations would be just as easy to change

[java] JSON Array iteration in Android/Java

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