我正在使用对象实例来创建构建器实例，然后使用构建方法来创建新实例。原始对象有一个列表，新对象是引用了同一列表还是它的副本？toBuilder()
@Getter
@Setter
@AllArgsConstructor
public class Library {
private List<Book> books;
@Builder(toBuilder=true)
public Library(final List<Book> books){
this.books = books;
}
}
Library lib2 = lib1.toBuilder().build();
lib2 书籍会引用与 lib1 书籍相同的列表吗？
是的，批注不会执行对象的深层复制，而只会复制字段的引用。@Builder(toBuilder=true)
List<Book> books = new ArrayList<>();
Library one = new Library(books);
Library two = one.toBuilder().build();
System.out.println(one.getBooks() == two.getBooks()); // true, same reference
您可以使用一个简单的技巧手动制作集合的副本：
List<Book> books = new ArrayList<>();
Library one = new Library(books);
Library two = one.toBuilder()
.books(new ArrayList<>(one.getBooks))
.build();
System.out.println(one.getBooks() == two.getBooks()); // false, different refs
