أنواع مختومة في جافا

record Person(String name, int age) { }

sealed interface Color permits BiColor, TriColor { }
	
record BiColor(int r, int g, int b) implements Color {}
record TriColor(int r, int g, int b) implements Color {}

PermittedSubtypes_attribute {
	u2 attribute_name_index;
	u4 attribute_length;
	u2 permitted_subtypes_count;
	u2 classes[permitted_subtypes_count];
}

java.lang.constant.ClassDesc<?>[] getPermittedSubtypes()
boolean isSealed()

var result = switch (color) {
	case BiColor bc -> 0x1;
	case TriColor tc -> 0x2;
}

sealed class Color
	
data class BiColor(val r: Int, val g: Int, val b: Int) : Color 
data class TriColor(val r: Int, val g: Int, val b: Int) : Color

public abstract class Color {
	private Color() {}
	
	public static class BiColor(int r, int g, int b) extends Color {}
	public static class TriColor(int r, int g, int b) extends Color {}
}

 matches(color).as(
       Color.BiColor.class,  bc -> System.out.println("bi color:  " + bc),
       Color.TriColor.class, tc -> System.out.println("tri color:  " + tc)
 );

 public static <V, T1, T2>
 void matches(V value,
                Class<T1> firstClazz,  Consumer<T1> firstBranch,
                Class<T2> secondClazz, Consumer<T2> secondBranch) {
        verifyExhaustiveness(value, new Class<?>[]{ firstClazz, secondClazz });
        Class<?> valueClass = value.getClass();

        if (firstClazz == valueClass) {
            firstBranch.accept((T1) value);
        } else if (secondClazz == valueClass) {
            secondBranch.accept((T2) value);
        }
}

public static <V> void verifyExhaustiveness(V value, Class<?>[] inputClasses) {
        SealedAttribute data = cacheSubclasses.computeIfAbsent(value.getClass(), SealedAttribute::new);
        Class<?>[] subClasses = data.getSubClasses();
        StringBuilder builder = new StringBuilder();
        boolean flag = false;

        if (subClasses.length != inputClasses.length) {
            throw new PatternException("Require " + inputClasses.length + " subclasses. " +
                                       "But checked class has " + subClasses.length + " subclasses.");
        }

        for (Class<?> subClass : subClasses) {
            for (Class<?> inputClass : inputClasses) {
                if (subClass == inputClass) {
                    flag = true;
                    break;
                }
            }

            if (!flag) {
                builder.append(subClass).append(",");
            }

            flag = false;
        }

        if (builder.length() >= 1) {
            throw new PatternException("Must to be exhaustive, add necessary " + builder.toString() +
                                       " branches or else branch instead");
        }
}

public final class SealedAttribute {
    private Class<?>[] subClasses;

    public SealedAttribute(Class<?> clazz) {
        Class<?> sealedClass = clazz.getSuperclass();

        if (!sealedClass.isAnnotationPresent(Sealed.class)) {
            throw new PatternException("Checked class must to be mark as sealed");
        }

        if (!Modifier.isAbstract(sealedClass.getModifiers())) {
            throw new PatternException("Checked class must to be abstract");
        }

        try {
            final Constructor<?> constructor = sealedClass.getDeclaredConstructor();

            if (!Modifier.isPrivate(constructor.getModifiers())) {
                throw new PatternException("Default constructor must to be private");
            }

            this.subClasses = sealedClass.getClasses();

            if (subClasses.length == 0) {
                throw new PatternException("Checked class must to has one or more visible subClasses");
            }

            for (Class<?> subclass : subClasses) {
                if (!Modifier.isStatic(subclass.getModifiers())) {
                    throw new PatternException("Subclass must to be static");
                }

                if (subclass.getSuperclass() != sealedClass) {
                    throw new PatternException("Subclass must to inherit from checked class");
                }
            }
        } catch (NoSuchMethodException e) {
            throw new PatternException("Checked class must to has default constructor " + e.getMessage());
        }
    }

    public Class<?>[] getSubClasses() {
        return subClasses;
    }
}

@Warmup(iterations = 3, time = 1)
@Measurement(iterations = 3, time = 1)
@Fork(3)
@State(Scope.Thread)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class UnionPatternBenchmark {
     private BiColor biColor;
	
    @Setup
    public void setup() {
        biColor = new BiColor.Red();
    }

    @Benchmark
    public int matchesSealedBiExpressionPlain() {
        if (biColor instanceof BiColor.Red) {
               return 0x1;
        } else if (biColor instanceof BiColor.Blue) {
               return 0x2;
        }

        return 0x0;
    }

    @Benchmark
    public int matchesSealedBiExpressionReflective() {
        return matches(biColor).as(
                BiColor.Red.class,  r -> 0x1,
                BiColor.Blue.class, b -> 0x2
        );
    }
}	

UnionPatternBenchmark.matchesSealedBiExpressionPlain           avgt    9   5,992 ±  0,332  ns/op
UnionPatternBenchmark.matchesSealedTriExpressionPlain          avgt    9   7,199 ±  0,356  ns/op

UnionPatternBenchmark.matchesSealedBiExpressionReflective      avgt    9  45,192 ± 11,951  ns/op
UnionPatternBenchmark.matchesSealedTriExpressionReflective     avgt    9  43,413 ±  0,702  ns/op