CODEWITHSUNDEEP
javarx-javarx-android
535A2
535A2

Reputation: 47

RxJava, get first item if exists

I'm trying to get the first item from a list using RxJava. However, I don't want it to throw an error if the item doesn't exist. Instead I want to be able to handle that myself by providing a default item.

The code I created below works correctly in retrieving the first item in a list. Though I can't figure out how to incorporate .exists() into it.

api.getLibraryEntries(username)
            .observeOn(AndroidSchedulers.mainThread())
            .flatMap(new Func1<List<Entry>, Observable<Entry>>() {
                @Override
                public Observable<Entry> call(List<Entry> Entries) {
                    return Observable.from(Entries);
                }
            })
            .first(new Func1<Entry, Boolean>() {
                @Override
                public Boolean call(Entry entry) {
                    return entry.getId() == id;
                }
            })
            .subscribe(
                    new Action1<Entry>() {
                        @Override
                        public void call(Entry entry) {
                            view.showEntry(entry);
                        }
                    },
                    new Action1<Throwable>() {
                        @Override
                        public void call(Throwable throwable) {
                            view.showError(throwable.getMessage());
                        }
                    });

Any help is appreciated.

Upvotes: 4

Views: 2511

Answers (1)

Egor Neliuba
Egor Neliuba

Reputation: 15054

There is a firstOrDefault operator:

// ...
.firstOrDefault(yourDefaultValue, new Func1<Entry, Boolean>() {
    @Override
    public Boolean call(Entry entry) {
        return entry.getId() == id;
    }
})
// ...

Upvotes: 4

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