尝试反序列化时出现 NullPointerException json

Question

我在尝试反序列化 json 时收到 NullPointerException。我正在尝试仅反序列化来自 https://api.covid19india.org/data.json

的 select JSON 个对象

我写过代码

import java.util.List;
    import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
    @JsonIgnoreProperties(ignoreUnknown = true)
    public class CovidData {
        List<Statewise> statewiseData;
        public List<Statewise> getStatewiseData() {
            return statewiseData;
        }
        public void setStatewiseData(List<Statewise> statewiseData) {
            this.statewiseData = statewiseData;
        }
        @Override
        public String toString() {
            return "CovidData [statewiseData=" + statewiseData + "]";
        }
    }

Statewise.java

public class Statewise {
    @JsonProperty("active")
    String active;
    
    public String getActive() {
        return active;
    }
    public void setActive(String active) {
        this.active = active;
    }
    
    @Override
    public String toString() {
        return "Statewise [active=" + active + ", confirmed=" + confirmed + ", deaths=" + deaths + ", deltaconfirmed="
                + deltaconfirmed + ", deltadeaths=" + deltadeaths + ", deltarecovered=" + deltarecovered
                + ", lastupdatedtime=" + lastupdatedtime + ", migratedother=" + migratedother + ", recovered="
                + recovered + ", state=" + state + ", statecode=" + statecode + ", statenotes=" + statenotes + "]";
    }
    
}

调用方法

@Test
    public void test1() {
        CovidData covidData=
        given()
        .when()
        .get("https://api.covid19india.org/data.json")
        .as(CovidData.class);
        
        List<Statewise> state=covidData.getStatewiseData();
        
        for (Statewise s : state)
            System.out.println(s.getActive());
    }

请帮忙

Answer 1

返回的 JSON 包含“statewise”属性。因此，要正确反序列化，您可以将 CovidData class 中的属性 List<Statewise> statewiseData 更改为 List<Statewise> statewise 或添加 JsonProperty 以将其映射到“statewise”

@JsonProperty("statewise")
List<Statewise> statewiseData;

尝试反序列化时出现 NullPointerException json

Getting NullPointerException while trying to deserialize json

java

json

jackson