Create a Json Array without the Json Array name

Question

I'm having problems creating a Json output in an array without the array name. Currently when I create one I get the following Json response.

{
  "values": [
    {
      "item1": "",
      "item2": "",
      "item3": "",
      "item4": ""
    }
  ]
}

But I want to remove following:

{
  "values": [
  ]
}

And have the end result look like the following:

[
   {
      "item1": "",
      "item2": "",
      "item3": "",
      "item4": ""
   },
   {
      "item1": "",
      "item2": "",
      "item3": "",
      "item4": ""
   }
]

Here is my code I'm currently using.

JSONArray jsonArray = new JSONArray();
jsonArray.put(new File(getFileName(base64), MimeTypes.ContentType(FileExtension.getType(base64)), folder, convertUriToBase64(), null));

Log.d(TAG, JsonUtil.toJson(jsonArray));

And here is my model class:

public class File {

    String fileName;
    int fileType;
    String fileFolder;
    String base64String;
    byte[] bytes;

    public File(String fileName, int fileType, String fileFolder, String base64String, byte[] bytes){
        this.fileName = fileName;
        this.fileType = fileType;
        this.fileFolder = fileFolder;
        this.base64String = base64String;
        this.bytes = bytes;
    }
}

Any help will be useful thank you!

@digitalbreed Yes and it doesn't return a valid json instead it returns a ["com.package.name.File@d917cac"] — Tihan-Nico Paxton
– Tihan-Nico Paxton, Commented Aug 24, 2021 at 20:39
Well, you put a File into it, which is not a valid JsonElement. — digitalbreed
– digitalbreed, Commented Aug 24, 2021 at 20:41
@digitalbreed I updated the question so you know what I mean — Tihan-Nico Paxton
– Tihan-Nico Paxton, Commented Aug 24, 2021 at 20:47

digitalbreed · Accepted Answer · 2021-08-24 20:57:52Z

1

Don't mix JSON elements with your own model. Here's an example using Gson.toJson which produces the expected result:

package test;

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;

public class GsonTest {

    // Your model class
    public static class Test {
        private int x;
        private int y;
        public Test(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }

    public static void main(String[] args) {
        List<Test> list = new ArrayList<>();
        list.add(new Test(1, 2));
        list.add(new Test(2, 3));
        System.out.println(new Gson().toJson(list));

        // output: [{"x":1,"y":2},{"x":2,"y":3}]

    }

}

answered Aug 24, 2021 at 20:57

digitalbreed

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3 Comments

Tihan-Nico Paxton Over a year ago

it works perfectly thank you, if I may ask how would one go about get lets say 2-10 items in a list. Like for example when you create a post on Facebook you can add a set amount of images to your post how would you go about getting all those images data and adding it an ArrayList?

digitalbreed Over a year ago

@Tihan-NicoPaxton not sure what you mean with "getting all those images data", but if you are asking about building a similar process, with file selection, preview, cropping, uploading, storage, security,... that's probably a bit too much to answer in a single SO question.

Tihan-Nico Paxton Over a year ago

Let's say you wanna post multiple images and upload it to a storage service, how would you go about it getting all those images data and adding it into the Json Arraylist. For example: 'List<Post> posts = new ArrayList(); posts.add(new Post("data"));' but instead of adding add whole time how would you get all them combined and add it as one, if that makes sense?

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