理解反转偶数二进制表示的函数(Understanding function which inverts binary representation of even number)

 flatMap()运算符采用一个附加参数，即它维护的同时订阅数。 这是一个测试样本： 
 
@Test
public void testStuff() throws Exception {
    Single<String> source;
    PublishSubject<String> src = PublishSubject.create();
    src
            .flatMap( s -> doStuff( s ).toObservable(), 5 )
            .subscribe( v -> { // process v
            } );
}

Single<String> doStuff( String subject ) {
    return Single.just( subject );
}
 
 如果doStuff()返回一个Single ，则必须将其转换为Observable ，因为这是flatMap()工作原理。 

The flatMap() operator takes an additional parameter which is the number of simultaneous subscriptions it maintains. Here is a test sample:
 
@Test
public void testStuff() throws Exception {
    Single<String> source;
    PublishSubject<String> src = PublishSubject.create();
    src
            .flatMap( s -> doStuff( s ).toObservable(), 5 )
            .subscribe( v -> { // process v
            } );
}

Single<String> doStuff( String subject ) {
    return Single.just( subject );
}
 
If doStuff() returns a Single, you have to convert it to an Observable, since that is what flatMap() works with.