Question

我尝试从Currency api响应中获取，该响应应为我显示用户货币指定的每月值，但是我在进行正确的改造调用时遇到了问题。哪里可能有问题？

我遇到的错误

java.lang.IllegalStateException：预期为字符串，但在第1行第38列$ .rates处为BEGIN_OBJECT。

带有改造调用的方法

String url = "https://api.exchangeratesapi.io/";
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(url)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    Api api = retrofit.create(Api.class);
    Call<testModel> modelCall = api.getMonthTest("2018-01-01", "2018-02-01", "USD");
    modelCall.enqueue(new Callback<testModel>() {
        @Override
        public void onResponse(Call<testModel> call, Response<testModel> response) {
            if (!response.isSuccessful()) {
                textView.setText(response.code());
            }

            List<testModel> models = Collections.singletonList(response.body());
            for (testModel model : models){
                String content = "";
                content += model.testRATES.getUsd();
                textView.append(content);
            }
        }
        @Override
        public void onFailure(Call<testModel> call, Throwable t) {
            textView.setText(t.getMessage());
        }
    });
 }
}

与api方法调用的接口

@GET("history")
Call<testModel> getMonthTest(
        @Query("start_at") String startAt,
        @Query("end_at") String endAt,
        @Query("symbols") String symbol);

POJO clas

public class testModel {

String base;
@SerializedName("end_at")
String endAt;
@SerializedName("start_at")
String startAt;
Map<String, String> rates;

Rates testRATES;

public String getBase() {
    return base;
}

public String getEndAt() {
    return endAt;
}

public String getStartAt() {
    return startAt;
}

public Map<String, String> getRates() {
    return rates;
}

public class Rates{
    @SerializedName("USD")
    Double usd;

    public Double getUsd() {
        return usd;
    }
}

Json回应

{
  "base": "EUR",
  "rates": {
    "2018-01-30": {
      "USD": 1.2421
    },
    "2018-01-15": {
      "USD": 1.2277
    },
    "2018-01-03": {
      "USD": 1.2023
    },
    "2018-02-01": {
      "USD": 1.2459
    },
    "2018-01-26": {
      "USD": 1.2436
    },
    "2018-01-12": {
      "USD": 1.2137
    },
    "2018-01-19": {
      "USD": 1.2255
    },
    "2018-01-16": {
      "USD": 1.223
    },
    "2018-01-22": {
      "USD": 1.2239
    },
    "2018-01-10": {
      "USD": 1.1992
    },
    "2018-01-08": {
      "USD": 1.1973
    },
    "2018-01-25": {
      "USD": 1.2407
    },
    "2018-01-29": {
      "USD": 1.2379
    },
    "2018-01-24": {
      "USD": 1.2352
    },
    "2018-01-11": {
      "USD": 1.2017
    },
    "2018-01-02": {
      "USD": 1.2065
    },
    "2018-01-31": {
      "USD": 1.2457
    },
    "2018-01-05": {
      "USD": 1.2045
    },
    "2018-01-18": {
      "USD": 1.2235
    },
    "2018-01-23": {
      "USD": 1.2249
    },
    "2018-01-04": {
      "USD": 1.2065
    },
    "2018-01-17": {
      "USD": 1.2203
    },
    "2018-01-09": {
      "USD": 1.1932
    }
  },
  "end_at": "2018-02-01",
  "start_at": "2018-01-01"
}

编辑

POJO类

@SerializedName("rates")
Map<String, Rates> rates;

改造电话

List<testModel> models = Collections.singletonList(response.body());
            for (testModel model : models) {
                currencyMap.put("2018-01-19",model.testRATES.getUsd());
                Iterator<Map.Entry<String, Double>> iterator = currencyMap.entrySet().iterator();
                while (iterator.hasNext()) {
                    Map.Entry entry = (Map.Entry) iterator.next();

                    key = (String) entry.getKey();
                    value = (Double) entry.getValue();

                    textView.append(key+"    "+value+"\n");
                }
            }

现在，我收到此错误

Attempt to invoke virtual method 'java.lang.Double com.example.currencyexchange.testModel$Rates.getUsd()' on a null object reference

Answer 1

在您的testModel（应该为TestModel）中，您拥有：

Map<String, String> rates;

在JSON中，有一个包含一些日期和Rates（应为Rate）的地图。日期为键，Rates为值。如果您想将日期反序列化为字符串，请在上方更改为：

Map<String, Rates> rates;

Answer 2

代替

Map<String, String> rates;

你能尝试

@SerializedName("rates")

List<Rates>rates

改装2错误-预期为字符串，但为BEGIN_OBJECT

2 个答案: