通过龙目岛自定义二传手

Question

Is there a way to modify the @Setter annotation to add some custom logic to all set methods built via lombok.

I have a class with the fields initialized with some default values. Now I only want to set the value in the fields if the value is not null.

Example, something that generates-

 public void setFoo(int foo) {
     if (foo != null) {
         this.foo = foo;
     }
 }

For example, if I am using the @Setter annotation on a Jersey Update Request class, instead of doing things like-

if (request.getFoo() != null) {
    this.foo = request.getFoo();
}

I should be able to directly do-

this.setFoo(request.getFoo());

with some results.

Answer 1

I assume you meant to use Integer instead of int , which does not allow null values and therefore solves your problem :)

In general, I would not recommend to change the logic of setFoo . Silently not setting foo on an arbitrary condition would expose its usage to bugs or at least misunderstandings.

My suggestion is to either use a custom method explicitly named setFooIfNotNull(Integer foo) . A possible alternative solution would be to mark the field foo with the annotation @NonNull to throw a NullPointerException in a case of null values.

From the Lombok @Setter annotation documentation 'small print' :

Any annotations named @NonNull (case insensitive) on the field are interpreted as: This field must not ever hold null. Therefore, these annotations result in an explicit null check in the generated setter.

Answer 2

您可以通过注释lombok的@Setter和@Getter来添加自己的自定义设置器，然后取消注释。否则，您可以使用@ lombok.experimental.Tolerate标记任何方法以将其从lombok中隐藏。

Answer 3

I'm adding this answer since Sumeet's is outdated as of 2019.

You can provide your own getter or setter logic by simply writing your own methods.

package com.example;

import lombok.Getter;

@Getter
public class Foo {

    //Will not generate a getter for 'test'
    private String test;

    //Will generate a getter for 'num' because we haven't provided our own
    private int num;

    public String getTest(){
        if(test == null){
            throw new Exception("Don't mind me, I'm just a silly exception");
        }

        return test;
    }
}