Lombok features - @NonNull

@NonNull

or: How I learned to stop worrying and love the NullPointerException.

@NonNull was introduced in lombok v0.11.10.

Overview

You can use @NonNull on the parameter of a method or constructor to have lombok generate a null-check statement for you.

Lombok has always treated various annotations generally named @NonNull on a field as a signal to generate a null-check if lombok generates an entire method or constructor for you, via for example @Data. Now, however, using lombok's own @lombok.NonNull on a parameter results in the insertion of just the null-check statement inside your own method or constructor.

The null-check looks like if (param == null) throw new NullPointerException("param is marked @NonNull but is null"); and will be inserted at the very top of your method. For constructors, the null-check will be inserted immediately following any explicit this() or super() calls.

If a null-check is already present at the top, no additional null-check will be generated.

With Lombok

import lombok.NonNull; public class NonNullExample extends Something {   private String name;      public NonNullExample(@NonNull Person person) {     super("Hello");     this.name = person.getName();   } }

Vanilla Java

import lombok.NonNull; public class NonNullExample extends Something {   private String name;      public NonNullExample(@NonNull Person person) {     super("Hello");     if (person == null) {       throw new NullPointerException("person is marked @NonNull but is null");     }     this.name = person.getName();   } }