TestSwitchExp.java

/*
javac --release 12 --enable-preview -Xlint:unchecked TestSwitchExp.java
java --enable-preview TestSwitchExp
*/

import java.util.stream.IntStream;

public class TestSwitchExp {
    static class Tuple<X, Y> {
        public final X x;
        public final Y y;
        public Tuple(X x, Y y) {
            this.x = x;
            this.y = y;
        }
    }

    enum FizzBuzzT {
        Fizz,
        Buzz,
        FizzBuzz,
        Number,
    }

    static Tuple<FizzBuzzT, Integer> as_fizzbuzz(int n) {
        var f = (n % 15 == 0) ? FizzBuzzT.FizzBuzz
            : (n % 3 == 0) ? FizzBuzzT.Fizz
            : (n % 5 == 0) ? FizzBuzzT.Buzz
            : FizzBuzzT.Number;
        return new Tuple<FizzBuzzT, Integer>(f, n);
    }
    
    static String fizzbuzz_to_str(Tuple<FizzBuzzT, Integer> t) {
        return switch (t.x) {
            case FizzBuzz -> "FizzBuzz";
            case Fizz -> "Fizz";
            case Buzz -> "Buzz";
            default -> t.y.toString();
        };
    }

    public static void main(String[] args) {
        IntStream.range(1, 101)
            .mapToObj(TestSwitchExp::as_fizzbuzz)
            .map(TestSwitchExp::fizzbuzz_to_str)
            .forEach(System.out::println);
    }
}