Generating equals / hashcode / toString using annotation
- by Bruno Bieth
I believe I read somewhere people generating equals / hashcode / toString methods during compile time (using APT) by identifying which fields should be part of the hash / equality test. I couldn't find anything like that on the web (I might have dreamed it ?) ...
That could be done like that :
public class Person {
@Id @GeneratedValue private Integer id;
@Identity private String firstName, lastName;
@Identity private Date dateOfBirth;
//...
}
For an entity (so we want to exlude some fields, like the id).
Or like a scala case class i.e a value object :
@ValueObject
public class Color {
private int red, green, blue;
}
Not only the file becomes more readable and easier to write, but it also helps ensuring that all the attributes are part of the equals / hashcode (in case you add another attribute later on, without updating the methods accordingly).
I heard APT isn't very well supported in IDE but I wouldn't see that as a major issue. After all, tests are mainly run by continuous integration servers.
Any idea if this has been done already and if not why ?
Thanks
