用简短，易读且有趣的方式编写的Java 8 FizzBu​​zz挑战

#1 楼

#2 楼

interface Substitute {
    Boolean condition(int);
    String transform(int);
}

class Fizzer : implements Substitute {
    Boolean condition(int x) { return x % 3 == 0; }
    String transform(int) { return "fizz"; }
};

class Buzzer : implements Substitute {
    Boolean condition(int x) { return x % 5 == 0; }
    String transform(int) { return "buzz"; }
};

class Mapper {
    List<Substitute> subs;

    void add_sub(Substitute sub) {
        subs.Add(sub);
    }    

    String execute(int input) { 
        String result;
        Boolean use_default = true;

        foreach (sub : subs) {
            if (sub.condition(input)) {
                result += sub.transform(input);
                use_default = false;
            }
        }
        if (use_default) return String.valueOf(input);
        return result;
    }
}

class FizzBuzz {
    static void main() { 
        Mapper map;
        map.add_sub(new Fizzer);
        map.add_sub(new Buzzer);

        for (int i=0; i<100; i++)
           System.out.println(map.execute(i));
    }
}

class DefaultMap : implements Substitute {
    Boolean condition(int) { return true; }
    String transform(int val) { return String.valueOf(val); }
};

// ... in main:
Mapper map;

map.add_sub(new FizzBuzzer);
map.add_sub(new Fizzer);
map.add_sub(new Buzzer);
map.add_sub(new DefaultMap);

for (int i=0; i<100; i++)
    System.out.println(map.execute(i));

#3 楼

String result = "";
if (value % 3 == 0) {
    result = "Fizz";
}
if (value % 5 == 0) {
    result += "Buzz";
}

return (toDefault) ? String.valueOf(value) : stringBuilder.toString();

static Stream<String> fizzBuzz(final int max) {
    return fizzBuzz(1, max);
}

#4 楼

private static String fizzBuzzify(final int value, final int fizzDivisor, final int buzzDivisor) {
  if (value % fizzDivisor == 0) {
    return (value % buzzDivisor == 0) ? "FizzBuzz" : "Fizz";  
  }
  return (value % buzzDivisor == 0) ? "Buzz" : Integer.toString(value);
}

#5 楼

/**
 * @return a function that simply returns its input value, except that it 
 *         returns {@code overWriteValue} each time the function as been
 *         called a multiple of {@code periodicity} times.
 */
public static <T> Function<T, T> overWriter(int periodicity, T overWriteValue) {
    AtomicInteger counter = new AtomicInteger(0);
    return value -> (counter.getAndIncrement() % periodicity) == 0  
                        ? overWriteValue 
                        : value;
}

public static void main(String[] args) {
    Stream<String> ints = IntStream.range(0, 100).mapToObj(Integer::toString);
    Function<String, String> fizzBuzzOverWriter = 
            overWriter(3, "Fizz")
            .andThen(overWriter(5, "Buzz")
            .andThen(overWriter(15, "FizzBuzz")));
    Stream<String> fizzBuzz = ints.map(fizzBuzzOverwriter);
    fizzBuzz.forEach(System.out::println);
}

#6 楼

private static String fizzBuzzify(final int value) {
  if (value % 3 == 0) {
    return (value % 5 == 0) ? "FizzBuzz" : "Fizz";  
  }
  return (value % 5 == 0) ? "Buzz" : Integer.toString(value);
}

#7 楼

private static enum Transformer implements IntFunction<Optional<String>> {
    FIZZ {
        @Override
        public Optional<String> apply(int value) {
            return value % 3 == 0 ? Optional.of("Fizz") : Optional.empty();
        }
    },
    BUZZ {
        @Override
        public Optional<String> apply(int value) {
            return value % 5 == 0 ? Optional.of("Buzz") : Optional.empty();
        }
    };
}

private static String transform(final int i) {
    final StringBuilder sb = Stream.of(Transformer.values()).
            map(t -> t.apply(i)).
            collect(StringBuilder::new, (builder, v) -> v.ifPresent(builder::append), StringBuilder::append);
    if (sb.length() == 0) {
        sb.append(i);
    }
    return sb.toString();
}

private static String transform(final int i) {
    return Stream.of(Transformer.values()).
            map(t -> t.apply(i)).
            filter(Optional::isPresent).
            map(Optional::get).
            collect(collectingAndThen(joining(), s -> s.isEmpty() ? Integer.toString(i) : s));
}

#8 楼

class FizzBuzzConsumer implements IntConsumer {

    @Override
    public void accept(int value) {
        if (value % 3 == 0) {
            System.out.print("Fuzz");
        }
        if (value % 5 == 0) {
            System.out.print("Buzz");
        }
        if (value % 3 != 0 && value % 5 != 0) {
            System.out.print(value);
        }
        System.out.println();
    }
}