Add Observable.endWith?

I’m using Observable.startWith but would also like to use a new method Observable.endWith say (I suppose concat is not available because of static method with same signature after erasure).

The driver for me is that my code (in java) is heaps uglier without it.

Suppose I have source1, source2 and I want to do some stuff to source1 and then append source2:

I have three options:

Use static concat:

Observable.concat(source1.take(20).buffer(2,1).filter(myFilter), source2);

Use startWith:

source2.startWith(source1.take(20).buffer(2,1).filter(myFilter));

or use a new endWith method:

source1.take(20).buffer(2,1).filter(myFilter).endWith(source2);

The last one is much clearer. Am I overlooking something or can we can add this method to the api?

Perhaps a method like ``append` is better because it might seem strange to see multiple concatenated endWiths:

source1.endWith(source2).endWith(source3);

or

source1.append(source2).append(source3);

[benjchristensen]

We now have concatWith as an instance method.

public final Observable<T> concatWith(Observable<? extends T> t1)

You can now write code like this:

    public static void main(String[] args) {
        Observable<Integer> source1 = Observable.from(1, 2, 3, 4, 5);
        Observable<Integer> source2 = Observable.range(100, 5);
        source1
                .take(20)
                .buffer(2, 1)
                .filter(l -> l.size() == 2)
                .map(l -> l.get(0) + l.get(1))
                .concatWith(source2)
                .forEach(System.out::println);
    }

This outputs:

3
5
7
9
100
101
102
103
104

[dkuteynikov]

Actually, it would be great to also have concatWithItem, because we already have both startWith and startWithItem, while concatWith doesn’t have a similar shortcut to omit writing Observable.just.