Using Lombok library, but how to customize/override the setter method

Question

I use lombok library in my java project.

@Data
public class Score {
   private long grade;
}

With this code, I have getter and setter automatically. e.g.

Score score = new Score();
score.setGrade(10);
// when I call score.getGrade(), I get 10.

But now I want to customize the setter method to introduce additional logics for the grade value. e.g.

public void setGrade(long grade) {
       // so the returned value from getter is always 1 bigger than what has been set.
       this.grade += 1; 
   }

Basically, I want to have score.setGrade(10) but score.getGrade() returns 11. That's override the setter. How to achieve it with lombok in use?

You can just define this method in the class, Lombok will use that then. — daniu, Feb 27 '20 at 14:12
No need to have `@override` annotation? Could you please post an example? — Leem, Feb 27 '20 at 14:14
You've got a good answer, the linked question has some additional related info. Concerning customization: You can't modify what Lombok setter does (e.g., notify observers or alike). All you can do is to stop Lombok from generating the setter and write your own. — maaartinus, Feb 27 '20 at 22:42

score 4 · Accepted Answer · answered Feb 27 '20 at 14:15

You can just write the getter method in the class. Lombok will not override methods. If a method that it should generate is already present, it will skip that one.

So you could do this:

@Data
public class Score {
  private long grade;

  public void setGrade(long grade) {
    this.grade = grade + 1;
  }
}

Or instead just override the getter:

@Data
public class Score {
  private long grade;

  public long getGrade() {
    return this.grade + 1;
  }
}

Edit: To add on your comment: @Override is only required if you override methods from superclasses or interfaces. Lombok injects the method directly into your class, thus no @Override is required (and it will cause an compiler error, because there is nothing that could be overridden).

What if I want to pass additional external parameter to the method, is that fine? — Leem, Feb 27 '20 at 14:20
@Leem that will result in the automatically generated setter with only one argument along the one with the one you declared. — daniu, Feb 27 '20 at 14:27

score 0 · Answer 2 · answered Feb 27 '20 at 14:19

This works fine for me

class Scratch {
    public static void main(String[] args) {
        MyDataClass object = new MyDataClass();
        object.setOverriddenSet("some value");
        if (!"fixed value".equals(object.getOverriddenSet())) {
            throw new RuntimeException();
        }
        System.out.println("all went well.");
    }
}

@Data
class MyDataClass {
    String generated;
    String overriddenSet = "fixed initial value";

    void setOverriddenSet(String setTo) {
        overriddenSet = "fixed value";
    }
}

Using Lombok library, but how to customize/override the setter method

2 Answers2