Java initialize null object with default - object

Question

I am trying to init object with default if not initialized by the user.
I want the user be able not to add params in the request but I will have it with the default value.
I'm not sure what I am missing but I get Null Pointer exception.
Having this object
#Builder
#Data
#Valid
#RequiredArgsConstructor
#AllArgsConstructor
#NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
public class Request {
private final List<Author> authors;
private final Config config;
private Params params;
}
#Builder
#AllArgsConstructor
#NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
#Data
#Setter(AccessLevel.NONE)
public class Params {
#Builder.Default private boolean adultOnly = false;
}
fun main(args: Array<String>) {
val request = Request(
authors,
config(
key,
level
)
)
also using builder throw null exception
val request = QueriesRequest.builder()
.userQueries(userQueries)
.configurationKey(
QueryConfigurationKey(configurationKey,
granularityLevel))
.site(site).build()
request.params.adultOnly // throw NULL , I expected to have the default false.
}
What I am missing?

Answer 1

The params field in the Request class is never initialized and remains null. You could set a default value for it:
#Builder
#Data
#Valid
#RequiredArgsConstructor
#AllArgsConstructor
#NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
public class Request {
private final List<Author> authors;
private final Config config;
#Builder.Default
private Params params = Params.builder().build();
}
I'm using the Params' builder itself to initialize the default value, so that you will get the default values as defined by that builder as well.