While programming in Java, I encountered the following problem.
when use Constructor: The following code works fine.
public class Generics<T> {
private T data;
public static <T> Generics<T> of(T data) {
return new Generics<>(data);
}
public Generics(T data) {
this.data = data;
}
}
when use builder: An error occurs saying that the Object type is provided as follows.
I used a builder provided by Project Lombok.
Why doesn’t the builder generic in the code above work?
>Solution :
Evidently Lombok generates a static generic builder() method. You can specify the generic type of a generic static method using <T> before the method name, as in:
return Generics.<T>builder()
.data(data)
.build();
If you don’t specify the generic type when you call builder(), you get a raw type, at which point generic type inference no longer works.