CODEWITHSUNDEEP
androidrx-java
Vadim Fedchuk
Vadim Fedchuk

Reputation: 85

emitting each item from list

I have a DAO method like this, which is working fine:

@Query("SELECT name FROM Weather")
Single<List<String>> getCity();

And a method in my activity:

mDatabase.getWeatherDao().getCity()
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .flatMap(new Function<List<String>, SingleSource<String>>() {
                @Override
                public SingleSource<String> apply(List<String> strings) throws Exception {
                    return ....; 
                }
            })
            .distinct()

next filter and so on.

How can I emit each item from List<String> strings in apply method, so that I can delete repeating (distinct()) items, filter and then use method toList()

Upvotes: 0

Views: 56

Answers (2)

ror
ror

Reputation: 3500

You could try something like this as well:

mDatabase.getWeatherDao().getCity()
                .toObservable()
                .flatMapIterable(r -> r)
                .distinct()
                .toList()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(..., ...)

This will work "as is" with strings, for more complex objects you'll need to make sure hashes and equals are working correct (of the entities inside the list).

Upvotes: 0

gpunto
gpunto

Reputation: 2852

You have to flatMap an Observable, like this:

.flatMapObservable(new Function<ArrayList<String>, ObservableSource<? extends String>>() {
    @Override
    public ObservableSource<? extends String> apply(ArrayList<String> source) throws Exception {
        return Observable.fromIterable(source);
    }
})

If you can use lambdas and method references you could replace all this ceremony with one of these:

// Lambda version
.flatMapObservable(source -> Observable.fromIterable(source))
// Method reference version
.flatMapObservable(Observable::fromIterable)

Upvotes: 1

Related Questions