If you want to parse unknown json, you should use something like this:

Iterator<?> iterator = jsonObject.keys();
while (iterator.hasNext()) {
   String key = (String)iterator.next();
   //do what you want with the key.                 
}  

I’m working on project in which I have to implement on API. This API repsonse is objects of ArrayList. Can you please help me with how to access the sub-arraylist. I’m using retrofit2 & GSON.

As shown in following JSON schema, brand names will be added in brandsonly by admin, and it will be added in allorders as a arraylist which have multiple sub-objects.

Like, if admin add Redmi in the brandsonly then it will create Redmi[] in the allorders.

{
    "status": "success",
    "brandsonly": [
        {
            "_id": "",
            "brandname": "SAMSUNG"
        },
        {
            "_id": "",
            "brandname": "VIVO"
        },
        {
            "_id": "",
            "brandname": "NOKIA"
        },
        {
            "_id": "",
            "brandname": "IPHONE"
        }
    ],
    "allorders": {
        "SAMSUNG": [],
        "VIVO": [],
        "NOKIA": [],
        "IPHONE": [
            {
                "_id": "",
                "order_id": "",
                "__v": 0,
                "adminconfirmation": 1,
                "finalpricetodeduct": 30950
            },
            {
                "_id": "",
                "order_id": "",
                "__v": 0,
                "adminconfirmation": 1,
                "finalpricetodeduct": 30950
            }
        ]
    }
}

My Retrofit call from activity:

final AllOrdersResponse allOrdersResponse = new AllOrdersResponse(userID);
Call<AllOrdersResponse> responseCall = retrofit_interface.allOrderResponse(allOrdersResponse, "Bearer " + AuthToken);

    responseCall.enqueue(new Callback<AllOrdersResponse>() {
    @Override
    public void onResponse(@NotNull Call<AllOrdersResponse> call, @NotNull Response<AllOrdersResponse> response) {
        AllOrdersResponse response1 = response.body();

    }

    @Override
    public void onFailure(@NotNull Call<AllOrdersResponse> call, @NotNull Throwable t) {
        if (t instanceof SocketTimeoutException)
           Toast.makeText(context, "Socket Time out. Please try again.", Toast.LENGTH_LONG).show();
        else
            Toast.makeText(context, t.toString(), Toast.LENGTH_LONG).show();
    }
});

AllOrdersResponse POJO Class.

public class AllOrdersResponse {

    @SerializedName("status")
    public String status;
    @SerializedName("allorders")
    public Allorders allorders;
    public List<Brandsonly> brandsonly;

    public String getStatus() {
        return status;
    }

    public Allorders getAllorders() {
        return allorders;
    }

    public List<Brandsonly> getBrandsonly() {
        return brandsonly;
    }
}

Also created the BrandResponse POJO class for each brand response.

public class BrandResponse{

    @SerializedName("_id")
    public String ID;
    public String order_id;
    public String __v;
    public String adminconfirmation;
    public String finalpricetodeduct;

    //And getters also there
}