how to parse Nested JSONArray in android

Question

This is my json :

{
  "posts": [
    {    
      "id": "c200",
      "title": "erfan",
      "email": "[email protected]",
      "address": "xx-xx-xxxx,x - street, x - country",
      "gender" : "male",
  "attachments":[
  {
    "url":"http://memaraneha.ir/wp-content/uploads/2016/11/light.jpg"
  }]},
  {
    "id": "c201",
    "name": "Johnny Depp",
    "email": "[email protected]",
    "address": "xx-xx-xxxx,x - street, x - country",
    "gender" : "male",
    "attachments":[
    {
      "url":"http://memaraneha.ir/wp-content/uploads/2016/11/renovate-old-home.jpg"}]
    }]
}

I want to get the title and url inside attachments array. I've tried this so far.

try {
    JSONObject jsonObj = new JSONObject(jsonStr);
    jsonContent jsonContent = new jsonContent(); //my class 

    JSONArray posts = jsonObj.getJSONArray("posts");

    for (int i = 0; i < posts.length(); i++) {
        JSONObject c = posts.getJSONObject(i);
        jsonContent.title = c.getString("title");

        JSONArray attachments=c.getJSONArray("attachments");

        for (int j=0;j<attachments.length();j++) {
            JSONObject a=attachments.getJSONObject(j);                     
            jsonContent.imgurl=a.getString("url");
        }

        listcontent.add(jsonContent);    //mylist
    }
} catch(Exception e) {}

Then I show the title and the url in a TextView , ImageView inside a RecyclerView. In card 1, I show the first title and image from the parsed json which works fine. But the problem is in card 2, which shows the title and image of card1 and doesn't matter how many json data we have, it just shows that same title and image in all items of my RecyclerView.

Here's the POJO for parsing the Json response.

public class jsonContent {
    public String title;
    public String imgurl;
}

I don't know what listcontent is, but unless the add method makes a copy of its argument, you need a new jsonContent object for each post element. You're adding the same object for every post. — Ted Hopp
– Ted Hopp, Commented Dec 15, 2016 at 17:25
@PavneetSingh please do not answer if similar question was already answered you have enough rep to mark as duplicate ... and yes, it was bazillion times like here , here — Selvin
– Selvin, Commented Dec 15, 2016 at 17:35
I never said anything about a duplicate. That was Selvin. I suggested moving the line jsonContent jsonContent = new jsonContent(); to inside the for loop. Have you tried that? — Ted Hopp
– Ted Hopp, Commented Dec 15, 2016 at 17:50
Pavneet "please do not answer" part was just a comment for your comment to Ted (which you deleted)... I didn't mean that you should really remove your answer... — Selvin
– Selvin, Commented Dec 15, 2016 at 19:45

Pavneet_Singh · Accepted Answer · 2016-12-15 17:25:31Z

1

you need to create new jsonContent object in every loop because currently you are just changing the values of same object in every iteration and adding it to the list.

 jsonContent jsonContent=null; //my class 

    JSONArray posts = jsonObj.getJSONArray("posts");
    for (int i = 0; i < posts.length(); i++) {
        jsonContent=new jsonContent(); //my class 
        //          ^^^^^^^^  create new object   
        JSONObject c = posts.getJSONObject(i);
        jsonContent.title=c.getString("title");

        JSONArray attachments=c.getJSONArray("attachments");
        for (int j=0;j<attachments.length();j++)
        {
            JSONObject a=attachments.getJSONObject(j);                     
            jsonContent.imgurl=a.getString("url");
        }
        listcontent.add(jsonContent);    //mylist
   }

Improvement : use getter and setter function instead of exposing your class fields as public

answered Dec 15, 2016 at 17:25

Pavneet_Singh

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3 Comments

Ted Hopp Over a year ago

This doesn't explain the behavior OP is reporting. I agree that a new jsonContent is probably needed for each loop, but if that's really the problem, then the list would be filled with the last values read, whereas OP is reporting that only the first values are showing up for all posts.

Pavneet_Singh Over a year ago

@TedHopp could be OP indication was in general that both first and all values are same so this is the only issue with data and clearly indicate the behavior

Erfan Over a year ago

@PavneetSingh just add this line jsonContent=new jsonContent(); in for loop and problem solve . i accept your answer please up vote my question selvin give me negetive vote :|

Reaz Masud · Accepted Answer · 2016-12-15 18:00:30Z

I would suggest using Gson for parsing your json string. Its clean and easy to use.

In your case, you might have to create these classes.

public class jsonContent {
    public String id;
    public String title;
    public String email;
    public String address;
    public String gender;
    public Attachment[] attachments;
}

public class Attachment {
    public String[] url;
}

Now as your POJO are created, you are now set to use Gson to parse the json string you got there.

Gson gson = new Gson();
jsonContent[] postArray = gson.fromJson(jsonStr, jsonContent[].class);

Now pass this postArray to your adapter and iterate through the array to show the proper data in your TextView and ImageView in each item of your RecyclerView.

To add Gson in your Android project, you just have to add the following dependency in your build.gradle.

dependencies {
    compile 'com.google.code.gson:gson:2.4'
}

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