java.lang.NullPointerException error on Retrofit onResponse

Question

Good day, I'm using Retrofit for the first time and I can't seem to get it to work. working on an app that get crypto currency rates in local currencies, here is the api link, JSON format

{
  "BTC": {
    "USD": 6019.1,
    "EUR": 5139.44,
    "NGN": 2136243.25
  },
  "ETH": {
    "USD": 290.98,
    "EUR": 250.03,
    "NGN": 103031.01
  }
}

Here are my models (from http://www.jsonschema2pojo.org/): UPDATED

public class CryptoCurrency {

@SerializedName("BTC")
@Expose
private BTC BTC;
@SerializedName("ETH")
@Expose
private ETH ETH;

public BTC getBTC() {
    return BTC;
}

public void setBTC(BTC BTC) {
    this.BTC = BTC;
}

public ETH getETH() {
    return ETH;
}

public void setETH(ETH ETH) {
    this.ETH = ETH;
}

public class BTC {

    @SerializedName("USD")
    @Expose
    private Double USD;

    @SerializedName("EUR")
    @Expose
    private Double EUR;

    @SerializedName("NGN")
    @Expose
    private Double NGN;

    public Double getUSD() {
        return USD;
    }

    public void setUSD(Double USD) {
        this.USD = USD;
    }

    public Double getEUR() {
        return EUR;
    }

    public void setEUR(Double EUR) {
        this.EUR = EUR;
    }

    public Double getNGN() {
        return NGN;
    }

    public void setNGN(Double NGN) {
        this.NGN = NGN;
    }


}


public class ETH {

    @SerializedName("USD")
    @Expose
    private Double USD;
    @SerializedName("EUR")
    @Expose
    private Double EUR;
    @SerializedName("NGN")
    @Expose
    private Double NGN;

    public Double getUSD() {
        return USD;
    }

    public void setUSD(Double USD) {
        this.USD = USD;
    }

    public Double getEUR() {
        return EUR;
    }

    public void setEUR(Double EUR) {
        this.EUR = EUR;
    }

    public Double getNGN() {
        return NGN;
    }

    public void setNGN(Double NGN) {
        this.NGN = NGN;
    }

}

}

My interface:

public interface CurrencyInterface {
    @GET("/data/pricemulti/")
    Call<CryptoCurrency.BTC> currency(@Query("crypto") String crypto, @Query("local") String local);
}

my onResponse method:

call.enqueue(new Callback<CryptoCurrency.BTC>() {
        @Override
        public void onResponse(Call<CryptoCurrency.BTC> call, Response<CryptoCurrency.BTC> response) {
            String currency = response.body().toString();
            Toast.makeText(getApplicationContext(), "result " + currency, Toast.LENGTH_LONG).show();
            Log.i("MainActivity", currency);

        }

        @Override
        public void onFailure(Call<CryptoCurrency.BTC> call, Throwable t) {

        }
    });

When I run the code and check my log I get this error:

java.lang.NullPointerException
at com.example.raynold.cryptorates.MainActivity$1.onResponse(MainActivity.java:53)
at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)

UPDATED---------

My MainActivity class

public class MainActivity extends AppCompatActivity {

private RecyclerView mCurrencyRecycler;
private Button mclickMe;
private CurrencyAdapter mCurrencyAdapter;
private List<CryptoCurrency> mCurrencyList;
private CurrencyInterface mCurrencyInterface;
private LinearLayoutManager mLinearLayoutManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mCurrencyRecycler = (RecyclerView) findViewById(R.id.rv_rates);
    mLinearLayoutManager = new LinearLayoutManager(this);
    mCurrencyRecycler.setLayoutManager(mLinearLayoutManager);
    mCurrencyRecycler.setHasFixedSize(true);
    mclickMe = (Button) findViewById(R.id.click_me);

    mCurrencyInterface = ApiClient.getApiClient().create(CurrencyInterface.class);

    Call<CryptoCurrency.BTC> call = mCurrencyInterface.currency("BTC", "NGN");

    call.enqueue(new Callback<CryptoCurrency.BTC>() {
        @Override
        public void onResponse(Call<CryptoCurrency.BTC> call, Response<CryptoCurrency.BTC> response) {
            String currency = response.body().toString();
            Toast.makeText(getApplicationContext(), "result " + currency, Toast.LENGTH_LONG).show();
            Log.i("MainActivity", currency);

        }

        @Override
        public void onFailure(Call<CryptoCurrency.BTC> call, Throwable t) {

        }
    });

    mclickMe.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

}

}

I will also like to know how i can get it to work with a recyclerview since the JSON is of object type not Array.

Possible duplicate of [Retrofit onResponse method not working, throws NullPointerException](https://stackoverflow.com/questions/39027025/retrofit-onresponse-method-not-working-throws-nullpointerexception) — Vishal Yadav, Oct 24 '17 at 05:08
@Vishal before creating this question i went through the answer on that question and it didn't help. — Raynold, Oct 24 '17 at 05:41

HassanUsman · Answer 1 · 2017-10-24T06:58:34.007

0

Change your onResponse method like this:

...........
call.enqueue(new Callback<CryptoCurrency.BTC>() {
        @Override
        public void onResponse(Call<CryptoCurrency.BTC> call, Response<CryptoCurrency.BTC> response) {
            String currency = response.getUSD().toString();
            Toast.makeText(getApplicationContext(), "result " + currency, Toast.LENGTH_LONG).show();
            Log.i("MainActivity", currency);

        }

        @Override
        public void onFailure(Call<CryptoCurrency.BTC> call, Throwable t) {

        }
    });

Try this solve your issue.

edited Oct 24 '17 at 06:58

answered Oct 24 '17 at 06:13

HassanUsman

1,787
1
20
38

did not work, cant call getJsonArray on response @HassanUsman – Raynold Oct 24 '17 at 06:20
Try `response.body().getJsonArray("BTC");` I updated my ans as well. – HassanUsman Oct 24 '17 at 06:35
can't still call getJsonArray on response.body.getJsonArray – Raynold Oct 24 '17 at 06:52
Now try i changed my code `String currency = response.getUSD().toString();` – HassanUsman Oct 24 '17 at 06:58
@HassanUsman shouldn't it be `String currency = response.body().getUSD().toString();` ? – amzer Oct 24 '17 at 08:01

score 0 · Answer 2 · answered Oct 24 '17 at 06:15

0

You should not use backslash at the start and end of URLs.

Try

@GET("data/pricemulti")

instead of

@GET("/data/pricemulti/")

answered Oct 24 '17 at 06:15

amzer

640
4
16

Lingeshwaran · Accepted Answer · 2017-10-24T10:30:39.627

0

public class CryptoCurrency {

        @SerializedName("BTC")
        @Expose
        private BTC BTC;
        @SerializedName("ETH")
        @Expose
        private ETH ETH;

        public BTC getBTC() {
            return BTC;
        }

        public void setBTC(BTC BTC) {
            this.BTC = BTC;
        }

        public ETH getETH() {
            return ETH;
        }

        public void setETH(ETH ETH) {
            this.ETH = ETH;
        }

    class ETH {
      ...
    }

    class BTC {
       ...
    }

}

In your interface CurrencyInterface use like

@GET("/data/pricemulti")
Call<CryptoCurrency> currency(@Query("fsyms") String crypto, @Query("tsyms") String local);

Handle like

Call<CryptoCurrency> call = mCurrencyInterface.currency("BTC", "NGN");

call.enqueue(new Callback<CryptoCurrency>() {
        @Override
        public void onResponse(Call<CryptoCurrency> call, Response<CryptoCurrency> response) {
            BTC btc = response.body().getBTC();
            Toast.makeText(getApplicationContext(), "result " + btc.getNGN(), Toast.LENGTH_LONG).show();

        }

        @Override
        public void onFailure(Call<CryptoCurrency.BTC> call, Throwable t) {

        }
    });

edited Oct 24 '17 at 10:30

answered Oct 24 '17 at 06:54

Lingeshwaran

579
4
15

please i need more info on this – Raynold Oct 24 '17 at 09:05
@Raynold now understand? – Lingeshwaran Oct 24 '17 at 09:13
"com.example.raynold.cryptorates.model.CryptoCurrency@412052f8". i get this as response – Raynold Oct 24 '17 at 09:55
debug and confirm that your calling url like same as api you like https://min-api.cryptocompare.com/data/pricemulti?fsyms=BTC&tsyms=NGN – Lingeshwaran Oct 24 '17 at 10:14
i changed it to @GET("data/pricemulti") Call currency(@Query("crypto") String crypto, @Query("local") String local); – Raynold Oct 24 '17 at 10:15
change interface as i mention above – Lingeshwaran Oct 24 '17 at 10:18
i have got this, com.example.raynold.cryptorates.model.CryptoCurrency@411ebc00 – Raynold Oct 24 '17 at 10:24
BTC btc = response.body().getBTC(); check it like this you will have content in that object you can use it now – Lingeshwaran Oct 24 '17 at 10:27
got this as response.. 10-24 11:35:33.077 29606-29606/com.example.raynold.cryptorates I/MainActivity retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall@4118a738: com.example.raynold.cryptorates.model.CryptoCurrency@411ed960com.example.raynold.cryptorates.model.CryptoCurrency$BTC@411edac0 – Raynold Oct 24 '17 at 10:39
still need help? local currency what ? – Lingeshwaran Oct 24 '17 at 11:09
the idea of the app is to get the a user create a card showing the user choice of local currency rate.. but i cant do that since it returns an object.. any ideas? – Raynold Oct 24 '17 at 11:13
now you have response which you searched in BTC or ETH you can use getter method to get a value from that object. – Lingeshwaran Oct 24 '17 at 11:16
yes i need help. when i change ("NGN") to ("USD") i get null response – Raynold Oct 24 '17 at 11:30
print the response and check USD have value or not – Lingeshwaran Oct 24 '17 at 11:33
how CryptoCurrency class change like? – Lingeshwaran Oct 24 '17 at 11:34
like from Call call = mCurrencyInterface.currency("BTC", "NGN"); to Call call = mCurrencyInterface.currency("BTC", "USD");. i get a null response – Raynold Oct 24 '17 at 11:42

score 0 · Answer 4 · answered Oct 24 '17 at 07:09

0

check if response.body() not null before this line

String currency = response.body().toString();

if response code not equal 200 your response will be null

answered Oct 24 '17 at 07:09

Nermeen Saleh

137
7

"com.example.raynold.cryptorates.model.CryptoCurrency$BTC@41204318" i get this as response @NermeenSaleh – Raynold Oct 24 '17 at 08:54
@Raynold response contains BTC object ,kindly override to string method on BTC class to return currency. – Nermeen Saleh Oct 24 '17 at 09:08
please can you give more info.. made the changes and got a java.lang.NullPointerException – Raynold Oct 24 '17 at 09:41

java.lang.NullPointerException error on Retrofit onResponse

4 Answers4