Rx java 如何基于列表项中以前的发射删除重复项

我有一个

可观察的
列表
：

Observable<List<String>> source = Observable.just(
        List.of("a", "c", "e"),
        List.of("a", "b", "c", "d"),
        List.of("d", "e", "f")
);

我可以累积以前的排放量，只需要像上面那样进行转换
 我使用
scan
操作符和助手类实现它，该类存储当前值和以前的值：

static class Distinct {
    final HashSet<String> previous;
    final List<String> current;

    public Distinct(HashSet<String> previous, List<String> current) {
        this.previous = previous;
        this.current = current;
    }
}

Observable<List<String>> source = Observable.just(
        List.of("a", "c", "e"),
        List.of("a", "b", "c", "d"),
        List.of("d", "e", "f")
);

source.scan(new Distinct(new HashSet<>(), new ArrayList<>()), (acc, item) -> {
    var newItem = new ArrayList<String>();
    item.forEach(i -> {
        if (acc.previous.add(i))
            newItem.add(i);
    });
    return new Distinct(acc.previous, newItem);
})
        .skip(1)
        .map(md -> md.current)
        .subscribe(System.out::println);

static class Distinct {
    final HashSet<String> previous;
    final List<String> current;

    public Distinct(HashSet<String> previous, List<String> current) {
        this.previous = previous;
        this.current = current;
    }
}

Observable<List<String>> source = Observable.just(
        List.of("a", "c", "e"),
        List.of("a", "b", "c", "d"),
        List.of("d", "e", "f")
);

source.scan(new Distinct(new HashSet<>(), new ArrayList<>()), (acc, item) -> {
    var newItem = new ArrayList<String>();
    item.forEach(i -> {
        if (acc.previous.add(i))
            newItem.add(i);
    });
    return new Distinct(acc.previous, newItem);
})
        .skip(1)
        .map(md -> md.current)
        .subscribe(System.out::println);

[a, c, e]
[b, d]
[f]