Convert LinkedHashMap into custom java object android

Question

I'm using jackson to read and write object into local json file.
It successfully read and write value. But problem is when I read value from file. and assign it to my object it give me an error.

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.testing.FeedItem

I know the reason of error because to read value from file jackons use LinkedHashMap So, LinkedHashMap can not cast to object(FeedItem)

Here is what I'm using.

PostFeed

  public class PostFeed{
       private String name;
       private List<FeedItem> feeditemList;
       // other code getter setter etc
  }

Reading Value from File

ObjectMapper objectMapper = new ObjectMapper();
PostFeed postFeed = objectMapper.readValue(offlinePrivateFeed, PostFeed.class);

FeedItem feedItem = postFeed.getFeedList().get(0); // Error

Update Write Value to local File

     ObjectMapper objectMapper = new ObjectMapper();
     objectMapper.writeValue(Utils.getOutputJsonFile("private-feed"), postFeed);

I found similar question LinkedhashMap can not cast to model Account But this question is not useful in my case, Almost I tried all answer but no one solve my problem.

Can you please let me know how can I solve this ?

Update: FeedItem

  public class FeedItem{
     private String name;
     private int badge;
     private Boolean allow;
     // other code getter setter etc
  }

Update: JSON File

{
 "feedName": "test123",
 "time" : "7-7-1994",
 "feedList": [
  {
   "name": "feedItemName",
   "badge": 4,
   "allow": false
  },
  {
   "name": "feedItemName",
   "badge": 1,
   "allow": true
  },
  {
   "name": "feedItemName",
   "badge": 2,
   "allow": false
  }

  ]

}

Update: Solution

This problem can be slove by converting LinkedHashMap into custom object FeedItem But question is how we can convert LinkedHashMap into Object ?

so, you know the reason of the error ... what more do you want us to explain to you? — Stultuske, Jun 27 '18 at 06:36
I want how can I assign `LinkedHashMap` to my object (FeedItem) ? — Azeem Haider, Jun 27 '18 at 06:42
ehm ... not. you might want to map the contents of your LinkedHashMap — Stultuske, Jun 27 '18 at 06:45
@Stultuske I only want to convert `LinkedHashMap` into object `FeedItem` — Azeem Haider, Jun 27 '18 at 06:57

score 0 · Answer 1 · answered Jun 27 '18 at 06:36

0

LinkedHashMap implements Map not List

https://docs.oracle.com/javase/7/docs/api/java/util/LinkedHashMap.html

Maybe change your feeditemList field type to LinkedHashMap

answered Jun 27 '18 at 06:36

Alays

112
2
19

I can not change it because I'm using Google Cloud Endpoint library and `FeedItem` is auto generated file – Azeem Haider Jun 27 '18 at 06:43

score 0 · Answer 2 · answered Jun 27 '18 at 06:46

0

Try this code if your PostFeed object not null then also feeditemList is not empty then used below code..

    if (postFeed!=null &&  !postFeed.getFeedList().isEmpty()){

        FeedItem feedItem = postFeed.getFeedList().get(0);
    }

answered Jun 27 '18 at 06:46

Bro, if you read my question It's not a `NullPointerExcdption` it's `ClassCastException` – Azeem Haider Jun 27 '18 at 06:47
sorry for that i think error into PostFeed postFeed = objectMapper.readValue(offlinePrivateFeed, PostFeed.class); this line not this line FeedItem feedItem = postFeed.getFeedList().get(0); – Jun 27 '18 at 06:49
you can debug and check it. – Jun 27 '18 at 06:49
I know where the error and what the error is Because problem is I don't know how to solve this – Azeem Haider Jun 27 '18 at 06:51
From local file, I updated my question see how I'm writing value in local file – Azeem Haider Jun 27 '18 at 06:56

score 0 · Answer 3 · answered Jun 27 '18 at 06:48

0

Try using this:

`  public class PostFeed{
       private String name;
       private LinkedHashMap<FeedItem> feeditemList;
//     private Map<FreedItem> freeditemlist
       // or you can also do this
       // other code getter setter etc
  }`

because LinkedHashMap implements Map not List

answered Jun 27 '18 at 06:48

Naman jain

66
11

As I already comment I can not change this file Because it is auto generated file from Google cloud storage – Azeem Haider Jun 27 '18 at 06:52
ok so you have to convert the retrieved data into FeedItem object – Naman jain Jun 27 '18 at 07:19
first try to know what you are getting in postFeed.getFeedList().get(0); by getting it into object type field than you can cast accordingly – Naman jain Jun 27 '18 at 07:25
I'm getting `LinkedHashMap` from `postFeed.getFeedList().get(0)` Cast this to `FeedItem` does not work same error – Azeem Haider Jun 28 '18 at 03:41
And In your code `LinkedHashMap` require two paramters `key` and `value` value type differ for each item. check update – Azeem Haider Jun 28 '18 at 03:44

Convert LinkedHashMap into custom java object android

3 Answers3