java-record

问题 I am reading the documentation of Records and don't understand the term "shallowly immutable". What do we mean by shallowly immutable ? And if it's immutable why we need a copy constructor? Why two "Hello Worlds!"? For all record classes, the following invariant must hold: if a record R's components are c1, c2, ... cn, then if a record instance is copied as follows: R copy = new R(r.c1(), r.c2(), ..., r.cn()); // copy constructor ? then it must be the case that r.equals(copy) . 回答1: Shallowly

问题 I really like the addition of records in Java 14, at least as a preview feature, as it helps to reduce my need to use lombok for simple, immutable "data holders". But I'm having an issue with the implementation of nullable components. I'm trying to avoid returning null in my codebase to indicate that a value might not be present. Therefore I currently often use something like the following pattern with lombok. @Value public class MyClass { String id; @Nullable String value; Optional<String>

问题 Using Micronaut bean validation for the record class is not working compile 'io.micronaut:micronaut-validation:2.2.1' Record class @Introspected public record ProductViewModel ( @JsonProperty("id") String id, @JsonProperty("name") @NotBlank @NotNull String name, @JsonProperty("description") @NotBlank String description, @JsonProperty("price") @NotBlank float price ) { } CURL curl --location --request POST 'http://localhost:8084/api/v1/product' \ --header 'Content-Type: application/json' \ -

来源： https://stackoverflow.com/questions/62455515/how-can-i-use-java-records-as-dto-with-modelmapper

来源： https://stackoverflow.com/questions/62455515/how-can-i-use-java-records-as-dto-with-modelmapper

来源： https://stackoverflow.com/questions/62455515/how-can-i-use-java-records-as-dto-with-modelmapper

来源： https://stackoverflow.com/questions/62455515/how-can-i-use-java-records-as-dto-with-modelmapper

问题 I am trying to use the JEP 359: Records (Preview) feature in Java with IntelliJ 2020.1.1 RC. I defined a class like this: package work.basil.example; import java.time.LocalTime; public record LocalTimeRange(LocalTime start , LocalTime stop) { } When I run a main method in another class using this LocalTimeRange class, no problem. When I do a Maven install I get this error: Error:(6,8) java: records are a preview feature and are disabled by default. ➥ How can I help Maven complete its install

问题 I am trying to use the JEP 359: Records (Preview) feature in Java with IntelliJ 2020.1.1 RC. I defined a class like this: package work.basil.example; import java.time.LocalTime; public record LocalTimeRange(LocalTime start , LocalTime stop) { } When I run a main method in another class using this LocalTimeRange class, no problem. When I do a Maven install I get this error: Error:(6,8) java: records are a preview feature and are disabled by default. ➥ How can I help Maven complete its install

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