So I'm trying to get my head around the webclient, but I keep getting a nullpointerexception, though my test work fine and say that object is not null. I also see my console making connection to the api. But when I ask the value, I get null.
Here are the two objects I use for it:
import com.fasterxml.jackson.annotation.JsonProperty;
public class Data {
@JsonProperty("message")
private String message;
@JsonProperty("status")
private String status;
public String getMessage() {
return message;
}
public String getStatus() {
return status;
}
}
public class Foto {
private Data data;
public Data getData() {
return data;
}
}
and then here I have my api call, I've put in my psvm to get console results:
try {
var test = client.get()
.uri("https://dog.ceo/api/breeds/image/random")
.retrieve()
.bodyToMono(Foto.class)
.block();
System.out.println(test.getData().getMessage());
} catch (WebClientResponseException.NotFound ex) {
ex.getMessage();
}
}
But as a console output for the system.out.println I keep receiving: Exception in thread "main" java.lang.NullPointerException: Cannot invoke "be.hi10.apiesTest.domain.Data.getMessage()" because the return value of "be.hi10.apiesTest.domain.Foto.getData()" is null at be.hi10.apiesTest.ApiesTestApplication.main(ApiesTestApplication.java:31)
What am I doing wrong here? I should be receiving a String representing a url to an image.
CodePudding user response:
Notice that your api returns response like this :
{
"message": "https://images.dog.ceo/breeds/collie-border/n02106166_346.jpg",
"status": "success"
}
Since you are trying to convert your response to Foto class which looks like this :
public class Foto {
private Data data;
public Data getData() {
return data;
}
}
For that to work your JSON should have to look like this :
"data":{
"message": "https://images.dog.ceo/breeds/collie-border/n02106166_346.jpg",
"status": "success"
}
but it doesnt and thats why your deserilization fails and you are getting NullPointerException
.
To make this work, change response type to Data
:
var test = client.get()
.uri("https://dog.ceo/api/breeds/image/random")
.retrieve()
.bodyToMono(Data.class)
.block();