I’m trying to deserialize a nested array from a JSON response. It’s the first time I’ve ever gotten an array of arrays and I’m not quite sure how to structure my class to handle it.

{
"prices": [
            [
                1641670404234,
                0.01582586939240936
            ],
            [
                1641674037525,
                0.015999047707867396
            ],
            [
                1641677655158,
                0.016072905257982606
            ]
            
            ...
         ],
}

If the brackets were { instead of [

{
"prices": {
            {
                1641670404234,
                0.01582586939240936
            },
            {
                1641674037525,
                0.015999047707867396
            },
            {
                1641677655158,
                0.016072905257982606
            }
           }
            ...
}

I could use

@SerializedName("prices")
private List<Price> prices;

public class Price {
    private long date;
    private BigDecimal price;
}

However since it is [ instead, I am quite unsure how to structure it.

I’ve tried adding another List wrapper to it but that throws an error

@SerializedName("prices")
private List<List<Price>> prices;

IllegalStateException: Expected BEGIN_OBJECT but was NUMBER at line 1 column 26 path $.prices[0][0]

I’ve also tried wrapping it with a JSONArray

 @SerializedName("prices")
private List<JSONArray<Price>> prices;

but that’s not quite right

I’ve tried searching other SO answers but I could not find any examples where it’s two consecutive [ [ brackets.

They are all { [ or [ {.

What’s the correct way to do it?

>Solution :

Assuming this is the correct JSON:

{
    "prices": [
        [
            1641670404234,
            0.01582586939240936
        ],
        [
            1641674037525,
            0.015999047707867396
        ],
        [
            1641677655158,
            0.016072905257982606
        ]
    ]
}

Then you can use this model to deserialize data to:

JAVA:

public class PricesModel {
    public ArrayList<ArrayList<double>> prices;
}

KOTLIN:

data class PricesModel (

  @SerializedName("prices" ) var prices : ArrayList<ArrayList<Int>> = arrayListOf()

)

Handy JSON converters to Java and Kotlin.