how to handle json response (2D array)?

Question

Hé all, I'm trying to solve an api response from: https://api.binance.com/api/v3/klines?symbol=BTCUSDT&interval=1d&limit=2

The response consist an 2D array of the Pojo24 class (see below) I want to fetch te response of the api into the Pojo24.class (getters and setters included). So in the end I want to put it into a database. I tried to use the Gson.class, unfortunately it didnt worked out. Is there somebody who can take me along with the solution? Tnx in advance!

   public class Pojo24{
private Long id;
    private Long openTime;
    private String open;
    private String high;
    private String low;
    private String close;
    private String volume;
    private Long closeTime;
    private String quoteAssesVolume;
    private Long numberOfTrades;
    private String tbbav;  //taker buy base asset volume
    private String tbqav;  //taker buy quote asset volume
    private String ignore;
}

---

package com.example.Binance24hr;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class Binance24hrApplication {

    public static void main(String[] args) {
        SpringApplication.run(Binance24hrApplication.class, args);

        
        String url = "https://api.binance.com/api/v3/klines?symbol=BTCUSDT&interval=1d&limit=2";
        Gson gson = new Gson();
        List<Object[]> result = gson.fromJson(url, new TypeToken<ArrayList<Object[]>>(){}.getType());

        List<Pojo24> pojo24List = result.stream()
                .map(e -> {
                    Pojo24 pojo24 = new Pojo24();
                   // pojo24.setId(new Double((Double) e[0]).longValue());
                    pojo24.setOpenTime(new Double((String) e[1]).longValue());
                    pojo24.setOpen((String) e[2]);
                    pojo24.setHigh((String) e[3]);
                    pojo24.setLow((String) e[4]);
                    pojo24.setClose((String) e[5]);
                    pojo24.setVolume(String.valueOf(e[6]));
                    pojo24.setCloseTime(new Double((String) e[7]).longValue());
                    pojo24.setQuoteAssesVolume(String.valueOf(e[8]));
                    pojo24.setNumberOfTrades(new Double((String) e[9]).longValue());
                    pojo24.setTbbav((String) e[10]);
                    pojo24.setTbqav((String) e[11]);
                    // pojo24.setIgnore((String) e[12])
                    return pojo24;
                })
                .collect(Collectors.toList());
    }
}

When im running this i got the following exception:

2022-01-27 19:33:15.661 INFO 10168 --- [ main] c.e.Binance24hr.Binance24hrApplication: Started Binance24hrApplication in 7.669 seconds (JVM running for 9.848) Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.Gson.fromJson(Gson.java:939) at com.google.gson.Gson.fromJson(Gson.java:892) at com.google.gson.Gson.fromJson(Gson.java:841) at com.example.Binance24hr.Binance24hrApplication.main(Binance24hrApplication.java:20) Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350) at com.google.gson.int ernal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:80) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61) at com.google.gson.Gson.fromJson(Gson.java:927)... 3 more

Answer 1

As I commented under OP, I can only find 12 elements in nested JSON array of given API response, but there are 13 fields in class Pojo24 . So, I assumed that the last field ignore can be ignored and you can first deserialize the response JSON string to a list of Object array, then assign each field to your class Pojo24 as follows:

Gson gson = new Gson();
List<Object[]> result = gson.fromJson(jsonStr, new TypeToken<ArrayList<Object[]>>(){}.getType());

List<Pojo24> pojo24List = result.stream()
        .map(e -> {
            Pojo24 pojo24 = new Pojo24();
            pojo24.setId(new Double((Double) e[0]).longValue());
            pojo24.setOpenTime(new Double((String) e[1]).longValue());
            pojo24.setOpen((String) e[2]);
            pojo24.setHigh((String) e[3]);
            pojo24.setLow((String) e[4]);
            pojo24.setClose((String) e[5]);
            pojo24.setVolume(String.valueOf(e[6]));
            pojo24.setCloseTime(new Double((String) e[7]).longValue());
            pojo24.setQuoteAssesVolume(String.valueOf(e[8]));
            pojo24.setNumberOfTrades(new Double((String) e[9]).longValue());
            pojo24.setTbbav((String) e[10]);
            pojo24.setTbqav((String) e[11]);
            // pojo24.setIgnore((String) e[12])
            return pojo24;
        })
        .collect(Collectors.toList());

Answer 2

package com.example.Binance24hr;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class Binance24hrApplication {

    public static void main(String[] args) {
        SpringApplication.run(Binance24hrApplication.class, args);

        
        String url = "https://api.binance.com/api/v3/klines?symbol=BTCUSDT&interval=1d&limit=2";
        Gson gson = new Gson();
        List<Object[]> result = gson.fromJson(url, new TypeToken<ArrayList<Object[]>>(){}.getType());

        List<Pojo24> pojo24List = result.stream()
                .map(e -> {
                    Pojo24 pojo24 = new Pojo24();
                   // pojo24.setId(new Double((Double) e[0]).longValue());
                    pojo24.setOpenTime(new Double((String) e[1]).longValue());
                    pojo24.setOpen((String) e[2]);
                    pojo24.setHigh((String) e[3]);
                    pojo24.setLow((String) e[4]);
                    pojo24.setClose((String) e[5]);
                    pojo24.setVolume(String.valueOf(e[6]));
                    pojo24.setCloseTime(new Double((String) e[7]).longValue());
                    pojo24.setQuoteAssesVolume(String.valueOf(e[8]));
                    pojo24.setNumberOfTrades(new Double((String) e[9]).longValue());
                    pojo24.setTbbav((String) e[10]);
                    pojo24.setTbqav((String) e[11]);
                    // pojo24.setIgnore((String) e[12])
                    return pojo24;
                })
                .collect(Collectors.toList());
    }
}

When im running this i got the following exception:

2022-01-27 19:33:15.661 INFO 10168 --- [ main] c.e.Binance24hr.Binance24hrApplication: Started Binance24hrApplication in 7.669 seconds (JVM running for 9.848) Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.Gson.fromJson(Gson.java:939) at com.google.gson.Gson.fromJson(Gson.java:892) at com.google.gson.Gson.fromJson(Gson.java:841) at com.example.Binan ce24hr.Binance24hrApplication.main(Binance24hrApplication.java:20) Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $ at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:80) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61) at com.google.gson.Gson.fromJson(Gson.java:927)... 3 more