🐻 🙎🏿 🥃 Java 15 e IntelliJ IDEA 🛢️ 👩🏻‍🤝‍👨🏾 🚓

Java 15 introdujo clases selladas e interfaces selladas , con la ayuda de las cuales fue posible restringir la jerarquía de clases e interfaces a nivel de sintaxis del lenguaje. Las posibles jerarquías ahora se definen de forma declarativa. Esta funcionalidad todavía se presenta en modo de vista previa .

También en Java 15, hay cambios en los registros que se introdujeron en Java 14. Y la coincidencia de patrones, por ejemplo, vino en Java 15 como una segunda vista previa sin cambios. Los bloques de texto de Java 13 se incluyen en Java 15 como una construcción de lenguaje estándar. No hay cambios en ellos en comparación con Java 14.

En este artículo, lo guiaré a través de todas las construcciones del lenguaje Java 15 nuevas y actualizadas, cómo pueden serle útiles y cómo usarlas en IntelliJ IDEA. Empecemos.

Clases e interfaces selladas

sealed, , . , , , — . ?

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class Plant {}
class Herb extends Plant {}
class Shrub extends Plant {}
class Climber extends Plant{}
class Cucumber extends Climber {}

, Gardener

() :

public class Gardener {
   int process(Plant plant) {
       if (plant instanceof Cucumber) {
           return harvestCucumber();
       } else if (plant instanceof Climber) {
           return sowClimber();
       } else if (plant instanceof Herb) {
           return sellHerb();
       } else if (plant instanceof Shrub) {
           return pruneShrub();
       } else {
           System.out.println("Unreachable CODE. Unknown Plant type");
           return 0;
       }
   }

   private int pruneShrub() { .. }
   private int sellHerb() { .. }
   private int sowClimber() { .. }
   private int harvestCucumber() { .. }
}

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sealed public class Plant permits Herb, Shrub, Climber {
}

final class Herb extends Plant {}
non-sealed class Shrub extends Plant {}
sealed class Climber extends Plant permits Cucumber{}

final class Cucumber extends Climber {}

, (accessibility) (extensibility). sealed- , . , , package-private . . sealed- .

permitted- (reflection) Class.permittedSubclasses()

. sealed- .

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IntelliJ IDEA

Java 15 IntelliJ IDEA 2020.2, 2020 . Java 15 "Project SDK" "15", "Project language level" — "15 (Preview) – Sealed types, records, patterns, local enums and interfaces".

Java 15 IntelliJ IDEA. "Project Structure" "Platform Settings" "SDKs", "+" "Download JDK". (Vendor), (Version) JDK.

Plant Gardener

sealed- - . else

process()

Gardener

. - else

- return

.

, Java 14 instanceof, Java switch

. switch

. " " , Plant

:

//      Java 15.
//       Java 
//   type-test-pattern  switch 
int processInAFutureJavaVersion(Plant plant) {
   return switch (plant) {
       case Cucumber c -> c.harvestCucumber();
       case Climber cl -> cl.sowClimber();
       case Herb h -> h.sellHerb();
       case Shrub s -> s.pruneShrub();
   }
}

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, , Plant

grow()

. Herb

final-, grow()

. Non-sealed Shrub

grow()

. Sealed- Climber

grow()

:

sealed abstract public class Plant permits Herb, Shrub, Climber {
   abstract void grow();
}
final class Herb extends Plant {
   @Override
   void grow() {
   }
}
non-sealed abstract class Shrub extends Plant {}
sealed class Climber extends Plant permits Cucumber{
   @Override
   void grow() {
   }
}
final class Cucumber extends Climber {}

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non-sealed

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sealed public interface Move permits Athlete, Person, Jump, Kick {
}
final class Athlete implements Move {}
record Person(String name, int age) implements Move {}
non-sealed interface Jump extends Move {}
sealed interface Kick extends Move permits Karate {}
final class Karate implements Kick {}

Java 15 – (record).

(records)

(records) - (value object). Java 14, Java 15 — .

IntelliJ IDEA, Java 14 IntelliJ IDEA. IntelliJ IDEA , .

Java 15 Java 14.

Java 15 . getTopPerformingStocks()

(stock), , .

List<String> getTopPerformingStocks(List<Stock> allStocks, LocalDate date) {
   // TopStock -   (Record)
   record TopStock(Stock stock, double stockValue) {}
   return allStocks.stream()
              .map(s -> new TopStock(s, getStockValue(s, date)))
              .sorted((s1, s2) -> Double.compare(s1.stockValue(), s2.stockValue()))
              .limit(2)
              .map(s -> s.stock.getName())
              .collect(Collectors.toList());
}

Java 15 . -.

public void createLocalInterface() {
   interface LocalInterface {
       void aMethod();
   }
   // ,  LocalInterface
}

public void createLocalEnum() {
   enum Color {RED, YELLOW, BLUE}
   // ,  enum Color
}

. , FOO

BAR

:

void test(int input) {
   enum Data {
       FOO(input), BAR(input*2); // .    input
       private final int i;
       Data(int i) {
           this.i = i;
       }
   }
}

(pattern matching) instanceof

Java- instanceof

. true, , . : - ifTrue - .

Java 14 instanceof

. , .

instanceof

( Java 14 ).

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. IntelliJ IDEA.

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Java 15 e IntelliJ IDEA