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1. Records are reference types (heap allocated), structs are not. C# have structs and will also be getting records with 9.0 2. Yes, you can make records of oth

1. Records are reference types (heap allocated), structs are not. C# have structs and will also be getting records with 9.0 2. Yes, you can make records of other records. 3. Not yet, but Project Valhalla will be bringing inline types to Java https://wiki.openjdk.java.net/display/valhalla/Main https://wiki.openjdk.java.net/display/valhalla/Main

skywhopper 7y ago
What do you mean, "structs are not"? As far as I can tell, structs do not exist in Java?
- kasperni 7y ago
  Structs in other similar languages, for example, C#
- xxs 7y ago
  Mark Valhalla project has been in the minds of people caring about performance for about 16years now... Struct was a suggested name.
- masklinn 7y ago
  What they mean is that `struct` in GC'd heap oriented languages is generally considered an alias for "a value type", that's what it is in C# or Swift. Records are shortcut syntax (and some runtime improvements) for a specific category of simple classes but they remain a heap-allocated reference type so calling records "struct" would be extremely misleading and would preclude (and / or make even weirder) the eventual inclusion of user-defined value types.
buckminster 7y ago
C# records: https://github.com/dotnet/roslyn/blob/features/records/docs/features/records.md https://github.com/dotnet/roslyn/blob/features/records/docs/... It's a struct or class but you only define the data members and the compiler auto-generates boiler plate like constructors, equality tests, etc.
- sk0g 7y ago
  So same as Kotlin Data Class? Records is a weird name, IMO.
  - int_19h 7y ago
    "Record" is what it was called in Algol and Pascal days.
    - riffraff 7y ago
      it's also what's still called by the functional crowd, I believe.
  - rienbdj 7y ago
    They are called records in F# which predates kotlin
xxs 7y ago
Personally I have been wanting to use headerless objects for a long time (pre java7). The best available option is DirectBuffer, still.
BubRoss 7y ago
Aren't classes already allocated on the heap? Why would C# need another type like that?
- UK-Al05 7y ago
  There low overhead data classes. It's takes a lot create a data class correctly. Including implementing equals, hash etc. Plus a good syntax for creating records. And encourages immutability.
- shawnz 7y ago
  The point of both the C# feature and the Java feature is to reduce boilerplate. They are not for improving the performance of apps.
- zamalek 7y ago
  The comment is wrong. Records are syntactical sugar for either value or reference types (depending on the language). They simply automatically implement equality, constructors and so forth.

skywhopper 7y ago

What do you mean, "structs are not"? As far as I can tell, structs do not exist in Java?

kasperni 7y ago
Structs in other similar languages, for example, C#
xxs 7y ago
Mark Valhalla project has been in the minds of people caring about performance for about 16years now... Struct was a suggested name.
masklinn 7y ago
What they mean is that `struct` in GC'd heap oriented languages is generally considered an alias for "a value type", that's what it is in C# or Swift. Records are shortcut syntax (and some runtime improvements) for a specific category of simple classes but they remain a heap-allocated reference type so calling records "struct" would be extremely misleading and would preclude (and / or make even weirder) the eventual inclusion of user-defined value types.

buckminster 7y ago

C# records: https://github.com/dotnet/roslyn/blob/features/records/docs/features/records.md https://github.com/dotnet/roslyn/blob/features/records/docs/... It's a struct or class but you only define the data members and the compiler auto-generates boiler plate like constructors, equality tests, etc.

sk0g 7y ago
So same as Kotlin Data Class? Records is a weird name, IMO.
- int_19h 7y ago
  "Record" is what it was called in Algol and Pascal days.
  - riffraff 7y ago
    it's also what's still called by the functional crowd, I believe.
- rienbdj 7y ago
  They are called records in F# which predates kotlin

xxs 7y ago

Personally I have been wanting to use headerless objects for a long time (pre java7). The best available option is DirectBuffer, still.

BubRoss 7y ago

Aren't classes already allocated on the heap? Why would C# need another type like that?

UK-Al05 7y ago
There low overhead data classes. It's takes a lot create a data class correctly. Including implementing equals, hash etc. Plus a good syntax for creating records. And encourages immutability.
shawnz 7y ago
The point of both the C# feature and the Java feature is to reduce boilerplate. They are not for improving the performance of apps.
zamalek 7y ago
The comment is wrong. Records are syntactical sugar for either value or reference types (depending on the language). They simply automatically implement equality, constructors and so forth.