Initialize list if list is null with lombok getter?

Question

I am currently replacing all my standard POJOs to use Lombok for all template code. I find that I am storing getters for lists because I want to return an empty list if the list has not been initialized. That is, I do not want getter to return null. If some kind of Lombok magic that I don’t know about can help me avoid this?

Sample Generated Code

private List<Object> list; public Object getList(){ return list; } 

Instead, I would like to:

 private List<Object> list; public Object getList(){ if (list == null) { return new ArrayList(); } return list; } 

Answer 1

You can achieve this by declaring and initializing the fields. Initialization will be performed upon initialization of the surrounding object.

 private List<Object> list = new ArrayList(); 

Abstract Lomboks @Getter provides a lazy attribute that allows lazy initialization.

  @Getter(lazy=true) private final double[] cached = expensiveInitMethod(); 

Documentation

Answer 2

I had the same questions as this one. While the answers above are useful in some ways, the exact solution is to use the @Builder and @Singular Lombok API annotations, like @Singular below in this code.

This worked perfectly for me.

 @Builder class MyClass{ @Singular private List<Type> myList; } 

This initializes myList with a nonzero List object. Although this question is old. But still posting this answer to help someone like me who will answer this question in the future

Answer 3

That is, I do not want getter to return null. If some kind of Lombok magic that I don’t know about can help me avoid this?

You don't need magic to happen. Just initialize the list .

Answer 4

You can override the recipient for anything using AccessLevel.NONE in the field.

Note that simply initializing the field does not protect you from clients calling the constructor with zero values ​​or calling the setter with zero values ​​(it may still be fine, depending on what you want).

for instance

 @Getter(AccessLevel.NONE) private Map<String, String> params; public Map<String, String> getParams() { return (params == null) ? new HashMap<>() : params; }