Converting an Arraylist<Object> method into RxJava Observable

Question

I came across RxJava for android and it's a good library. I'm a beginner and i understand how it works but i have some trouble converting my old codes to RxJava style programming.

Below is my old code I'm using to populate my arraylist of objects.

public ArrayList<AppModel> getMyAppList(PackageManager pm, List<ApplicationInfo> list){
        ArrayList<AppModel> temp = new ArrayList<>();


        for(int d=0;d<list.size();d++){
            ApplicationInfo infos = list.get(d);
            AppModel model = new AppModel();
            model.set_id(d);
            model.setApp_name(""+infos.loadLabel(pm));
            model.setPackage_name(""+infos.packageName);
            model.setIcon(infos.loadIcon(pm));
            //Log.e("resolve "," "+infos.loadIcon(pm));
            temp.add(model);
        }

        return temp;
    }

What I want is to convert this method into an Observable and to take advantage of RxJava features.

public Observable<AppModel> getMyAppList(PackageManager pm, List<ApplicationInfo> list){



        return Observable
                .from(list)
                .subscribeOn(Schedulers.computation())
                .doOnNext(new Action1<ApplicationInfo>() {
                    @Override
                    public void call(ApplicationInfo applicationInfo) {
                        AppModel mm = new AppModel();
                        mm.set_id(applicationInfo.hashCode());
                        mm.setApp_name(""+applicationInfo.loadLabel(pm));
                        mm.setPackage_name(""+applicationInfo.packageName);
                        mm.setIcon(applicationInfo.loadIcon(pm));


                        //add the models to a list

                    }
                }).//return as Observable<AppModel>
    }

I'm currently stuck how to return the object into Observable or should be my method return an Observable<ArrayList<AppModel>>> instead.

should my method return an Observable<ArrayList<AppModel>>> instead - yes, likely. Observable is not a replacement for arraylist — Tim
– Tim, Commented Jan 15, 2018 at 15:57
You can use toList() at the end to convert it to a List<AppModel> — dazza5000
– dazza5000, Commented Jan 15, 2018 at 16:00
Hi @TimCastelijns thanks for the edit. Can't Observable behave as a list instead? Since Observable<AppModel> iterates objects using doOnNext methods. — cattarantadoughan
– cattarantadoughan, Commented Jan 15, 2018 at 16:02
Hi @dazza5000, using toList returns it as an Observable<ApplicationInfo > instead. — cattarantadoughan
– cattarantadoughan, Commented Jan 15, 2018 at 16:05
then you probably need to use a flatMap to get it into the type you want or have the method except a list of ApplicationInfo — dazza5000
– dazza5000, Commented Jan 15, 2018 at 16:06

Siavash Abdoli · Accepted Answer · 2018-01-15 16:19:03Z

3

you should use map instead of doOnNext

public Observable<AppModel> getMyAppList(final PackageManager pm, List<ApplicationInfo> list){



    return Observable
            .from(list)
            .subscribeOn(Schedulers.computation())
            .map(new Func1<ApplicationInfo, AppModel >() {
                @Override
                public AppModel call(ApplicationInfo applicationInfo) {
                    AppModel mm = new AppModel();
                    mm.set_id(applicationInfo.hashCode());
                    mm.setApp_name(""+applicationInfo.loadLabel(pm));
                    mm.setPackage_name(""+applicationInfo.packageName);
                    mm.setIcon(applicationInfo.loadIcon(pm));

                    return mm;
                }
            });
}

and if you want to return list instead of emit each item add this after map:

.toList();

edited Jan 15, 2018 at 16:19

answered Jan 15, 2018 at 16:11

Siavash Abdoli

1,8613 gold badges22 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

cattarantadoughan Over a year ago

Thanks man! this is what i need. I didn't know map will have 2 params that i can use. Very appreciated! @Siavash

Collectives™ on Stack Overflow

Converting an Arraylist<Object> method into RxJava Observable

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related