@Test
    public void cast() {
        System.out.println("######cast#####");
        List<Float> source = new ArrayList<>();
        source.add(199f);
        source.add(102f);
        source.add(100f);
        Flowable flowable = Flowable.fromIterable(source);

        flowable.cast(Number.class).subscribe(new
 
 Consumer<Number>() {
            @Override
            public void accept(Number number) throws Exception {
                System.out.println(number);
            }
        });

    }


測試結果
######cast#####
199.0
102.0
100.0

Process finished with exit code 0