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import java.util.List;
import java.util.Locale;
aspect SwitchPatternPreview3Aspect {
Object around(Object o) : execution(* doSomethingWithObject(*)) && args(o) {
System.out.println(switch (o) {
case null -> "null";
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
case Double d -> String.format(Locale.ENGLISH, "double %f", d);
case String s -> String.format("String %s", s);
default -> o.toString();
});
return proceed(o);
}
before(Shape s) : execution(* doSomethingWithShape(*)) && args(s) {
System.out.println(switch (s) {
case Circle c when (c.calculateArea() > 100) -> "Large circle";
case Circle c -> "Small circle";
default -> "Non-circle";
});
}
after(S s) : execution(* doSomethingWithSealedClass(*)) && args(s) {
System.out.println(switch (s) {
case A a -> "Sealed sub-class A";
case B b -> "Sealed sub-class B";
case C c -> "Sealed sub-record C";
});
}
Object around(Integer i): execution(* doSomethingWithInteger(*)) && args(i) {
// This used to work in preview 4 (Java 20), but fails during runtime with
// java.lang.IndexOutOfBoundsException: Index 4 out of bounds for length 4
// in ECJ 3.36.0-SNAPSHOT with Java 21.
// See:
// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/1466.
//
// TODO: Activate when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/1466 is fixed.
/*
System.out.println(
switch (i) {
case null -> "value unavailable: " + i;
case -1, 1 -> "absolute value 1: " + i;
case Integer value when value > 0 -> "positive integer: " + i;
default -> "other integer: " + i;
}
);
*/
return proceed(i);
}
}
class Shape {}
class Rectangle extends Shape {}
class Circle extends Shape {
private final double radius;
public Circle(double radius) { this.radius = radius; }
double calculateArea() { return Math.PI * radius * radius; }
}
sealed interface S permits A, B, C {}
final class A implements S {}
final class B implements S {}
record C(int i) implements S {} // Implicitly final
class Application {
public static void main(String[] args) {
doSomethingWithObject(null);
doSomethingWithObject(123);
doSomethingWithObject(999L);
doSomethingWithObject(12.34);
doSomethingWithObject("foo");
doSomethingWithObject(List.of(123, "foo", 999L, 12.34));
doSomethingWithShape(new Rectangle());
doSomethingWithShape(new Circle(5));
doSomethingWithShape(new Circle(6));
doSomethingWithSealedClass(new A());
doSomethingWithSealedClass(new B());
doSomethingWithSealedClass(new C(5));
doSomethingWithInteger(-1);
doSomethingWithInteger(0);
doSomethingWithInteger(42);
doSomethingWithInteger(-99);
doSomethingWithInteger(Integer.valueOf(123));
doSomethingWithInteger(null);
}
public static Object doSomethingWithObject(Object o) { return o; }
public static void doSomethingWithSealedClass(S s) {}
public static void doSomethingWithShape(Shape s) {}
public static Object doSomethingWithInteger(Integer o) { return o; }
}
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