java-record

问题 I have a record and want to add default constructor to it. public record Record(int recordId) { public Record { } } But it created constructor with int param. public final class Record extends java.lang.Record { private final int recordId; public Record(int); //other method } How can we add a default constructor to a record? 回答1: To split hairs, you cannot ever define a default constructor, because a default constructor is generated by the compiler when there are no constructors defined, thus

问题 I’m hoping that Java 14 records actually use less memory than a similar data class. Do they or is the memory usage the same? 回答1: To add to the basic analysis performed by @lugiorgi and a similar noticeable difference that I could come up with analyzing the byte code, is in the implementation of toString , equals and hashcode . On one hand, previously used class with overridden Object class APIs looking like public class City { private final Integer id; private final String name; // all-args,

问题 I’m hoping that Java 14 records actually use less memory than a similar data class. Do they or is the memory usage the same? 回答1: To add to the basic analysis performed by @lugiorgi and a similar noticeable difference that I could come up with analyzing the byte code, is in the implementation of toString , equals and hashcode . On one hand, previously used class with overridden Object class APIs looking like public class City { private final Integer id; private final String name; // all-args,

问题 I love project Lombok but in these days I'm reading and trying some of the new features of java 14. Inside the new capability, there is the record keyword that allows creating a class with already built-in the following functionality: constructor, private final fields, accessors, equals/hashCode, getters, toString methods. Now my question is: is better to rely on the feature of Lombok or should we start using the record functionality: Is better to use this: record Person (String name, String

问题 I am trying to see if I can replace my existing Pojos with the new Record classes in Java 14. But unable to do so. Getting following error: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of com.a.a.Post (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator) I get that the error is saying the record has no constructors, but from what I see the record class takes care of it in the

问题 I am trying to see if I can replace my existing Pojos with the new Record classes in Java 14. But unable to do so. Getting following error: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of com.a.a.Post (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator) I get that the error is saying the record has no constructors, but from what I see the record class takes care of it in the

问题 I am trying to see if I can replace my existing Pojos with the new Record classes in Java 14. But unable to do so. Getting following error: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of com.a.a.Post (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator) I get that the error is saying the record has no constructors, but from what I see the record class takes care of it in the

问题 I have been working with the following class named City @ToString @AllArgsConstructor public class City { Integer id; String name; } and tried to convert it to a record called CityRecord as record CityRecord(Integer id, String name) {} // much cleaner! But moving to such a representation, one of our unit tests starts failing. The tests internally deal with a list of cities read from a JSON file and mapped to an object further counting the cities while grouping them under into a Map .

问题 Java 14 introduced records feature. Record creates getter with the same name as field, so one would write print(person.name()) for example. But old Java bean convention dictates that one should name this method as getName() . Using both styles in the same code base does not look very nice. Migrating everything to records is not possible, as they are too limited to replace all use-cases. Is there any official or semi-official guidelines how to name getters and setters after Java 14 in new code

问题 Java 14 introduced records feature. Record creates getter with the same name as field, so one would write print(person.name()) for example. But old Java bean convention dictates that one should name this method as getName() . Using both styles in the same code base does not look very nice. Migrating everything to records is not possible, as they are too limited to replace all use-cases. Is there any official or semi-official guidelines how to name getters and setters after Java 14 in new code