Jackson databind read json tri-dimensional array

Question

I want to read a json Array and put it, if possible, into an int tri-dimensional array.

The data will look like this, I can change it's design to suit my needs as it is not done yet. The values are dumb but what is good to know is that (Caution mindf*ck ahead) I have to nest an unknown number of arrays containing integers, two times in an array that is repeated three times or less in the root node.

I.E. int[3 or less][2][unknown int] = val

I wrote the keys to improve readability, they may or may not be part of the actual json.

{
    demand : {
        0 : {
           0 :{
               0 :22,
               1 :32,
               2 :21
            },
            1 :{
               0 :2762,
               1 :352,
               2 :231
            }
        },
        1 :{
            0 :{
               0 :222,
               1 :232,
               2 :621
             },
             1 :{
               0 :272,
               1 :37762,
               2 :261 
             }
         }
     }
}

The point is that the keys and values are all integers and I would like to create an int [][][] with it. I think that the answer is in this doc : Jackson Full Databinding but I do not understand properly how it would work for my data.

I'm thinking about some ObjectMapper.readValue(json, new TypeReference>() { })` and will continue to look into this but I don't have much hope.

Thanks for any help!

Edit Here is the actual valid JSON

[  [   [  22, 32,  21   ],  [ 2762,  352, 231 ] ], [    [  222, 232,  621 ],  [ 272,  37762, 261]] ]

Answer 1

Serializing/Deserializing arrays with Jackson is the same as serializing anything else:

public class App 
{
    public static void main(String[] args) throws JsonProcessingException {

        int[][][] a = new int[2][3][2];
        a[0][2][0] = 3;

        ObjectMapper om = new ObjectMapper();

        // Serialize to JSON
        String json = om.writeValueAsString(a);
        System.out.println(json);

        // deserialize back from JSON
        a = om.readValue(json, int[][][].class);
        System.out.println(a[0][2][0]);

   }
}

output:

[[[0,0],[0,0],[3,0]],[[0,0],[0,0],[0,0]]]
3

That said, unless you know it's always going to be a three dimensional array, you're be better served using Lists

Answer 2

I'm not sure if this answers your question but I think you can always use iterator and split, for instance:

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import net.sf.json.JSONObject;

public class test {
    /**
 * @param args
 */
@SuppressWarnings("unchecked")
public static void main(String[] args) {
    Map <String, Object> map1 = new HashMap<String, Object>();
    Map <String, Object> map2 = new HashMap<String, Object>();
    Map <String, Map> map3 = new HashMap<String, Map>();
    map1.put("0","22,32,21");
    map1.put("1", "2762,352,231");
    map2.put("0", "222,232,621");
    map2.put("1","272,37762,261");
    map3.put("0",map1 );
    map3.put("1",map2);
    JSONObject jsonobj = JSONObject.fromObject(map3);  // creating json object
    Iterator it = jsonobj.keys();
    int maxZ = 0; //find out the length of the last dimension
    while(it.hasNext()) {
        JSONObject jobj = (JSONObject) jsonobj.get(it.next());
        Iterator it2 = jobj.keys();
        while(it2.hasNext()) {
            if(((String)jobj.get(it2.next())).split(",").length > maxZ){
                maxZ= ((String)jobj.get(it2.next())).split(",").length;
                }
        }
    }
    int[][][] result= new int [jsonobj.size()][2][maxZ]; //creating 3D array of the right size
    int x = 0, y = 0, z = 0;
    it = jsonobj.keys();
    while(it.hasNext()) {
        JSONObject jobj = (JSONObject) jsonobj.get(it.next());
        Iterator it2 = jobj.keys();
        y = 0; //reset y
        while(it2.hasNext()) {
            String[]s =((String)jobj.get(it2.next())).split(",");
            z = 0; //reset z
            for (String str : s) {
                result[x][y][z] = Integer.parseInt(str);
                z++;
            }
        y++;
        }
    x++;
    }
    for (int i = 0; i < x; i++) {
        for (int j = 0; j < y; j++) {
            for (int k = 0; k < z; k++) {
                System.out.print(result[i][j][k]);
                System.out.print(" ");
            }
            System.out.println("\n");
            }
        }
    }
}

output:

272 37762 261 

222 232 621 

2762 352 231 

22 32 21 

not sure why this is in the back order, sorry if this doesn't help :P