RxJava and Using RxJava

in MVPTOI DUONG VAN (STEVE)

ANDROID DEVELOPER – INNOVATUBE SOLUTION

Definition

RxJava

A library for composing asynchronous and event-base programming using

observable sequences for the JavaVM

A combination from the Observer pattern, the Iterator pattern, and functional

programming

A lot of functions to create, combine and filter any of those streams

Definition

// Convert any object into an Observable that emits that object

Observable.just("Hello world!");

// Converts an Array into an Observable that emits the items in the Array.

Integer[] numbers = {0, 1, 2, 3, 4, 5};

Observable.from(numbers);

// From Retrofit

public Observable<SearchResult> searchRepo(String name, String sort) {

return mGithubService.searchRepo(name, sort);

}

@GET("search/users")

Observable<SearchResult> searchRepo(@Query("q") String name, @Query("sort") String sort);

// Custom from anything

Observable<String> myObservable = Observable.create(new Observable.OnSubscribe<String>() {@Override

public void call(Subscriber<? super String> subscriber) {

try {

String s = doSomething();

subscriber.onNext(s);

subscriber.onCompleted();

} catch (Exception e) {

subscriber.onError(e);

}

}

});

Observable

Scheduler

private void heavyComputationFunction() {

Observable.create(new Observable.OnSubscribe<String>() {

@Override

public void call(Subscriber<? super String> subscriber) {

for (int i = 0; i < 1000000; i++) {

subscriber.onNext(i + "");

}

subscriber.onCompleted();

}

}).subscribeOn(Schedulers.computation()) // Scheduler intended for computational work

.subscribe(s -> {

Log.d(TAG, s);

});

}

Scheduler

private void networkCallGetRepo(String search, String sort) {

mSbuscription = mDataManager.searchRepo(search, sort)

.subscribeOn(Schedulers.io())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Subscriber<Item>() {

@Override

public void onCompleted() {

}

@Override

public void onError(Throwable e) {

e.printStackTrace();

}

@Override

public void onNext(Item item) {

getMvpView().addUser(item);

}

});

}

Operators// Log the length of input string

Observable.just("Hello world")

.map(s -> s.length())

.map(integer -> integer.toString())

.subscribe(string -> {

Log.d(TAG, string);

});

// Log the even number

Integer[] integers = {1, 2, 3, 4, 5, 6, 7, 8};

Observable.from(integers)

.filter(integer -> (integer % 2 == 0))

.map(integer -> integer.toString())

.subscribe(s -> {

Log.d(TAG, s);

});

SchedulerObservable.create(new Observable.OnSubscribe<String>() {

@Override

public void call(Subscriber<? super String> subscriber) {

getActivityComponent().inject(ReposActivity.this);

mReposPresenter.attachView(ReposActivity.this);

subscriber.onCompleted();

}

})

.subscribeOn(Schedulers.io())

.observeOn(Schedulers.io())

.subscribe(new Observer<String>() {

@Override

public void onCompleted() {

getRepos(mRepoUrl);

}

@Override

public void onError(Throwable e) {

e.printStackTrace();

}

@Override

public void onNext(String s) {

}

});

Schedulerpublic void getRepos(String url) {

mSbuscription = mDataManager.getRepos(url)

.filter(repos -> repos != null)

.concatMap(repos -> Observable.from(repos))

.subscribeOn(Schedulers.io())

.observeOn(AndroidSchedulers.mainThread())

.subscribe(new Subscriber<Repo>() {

@Override

public void onCompleted() {

}

@Override

public void onError(Throwable e) {

e.printStackTrace();

}

@Override

public void onNext(Repo repo) {

getMvpView().addRepo(repo);}

});

}

Subscriber

Observable.just("Action1")

.subscribe(new Action1<String>() {

@Override

public void call(String s) {

Log.d(TAG, s);

}

});

Observable.just("Subscriber")

.subscribe(new Subscriber<String>() {

@Override

public void onCompleted() {

}

@Override

public void onError(Throwable e) {

}

@Override

public void onNext(String s) {

Log.d(TAG, s);

}

});

Observable.just("Observer")

.subscribe(new Observer<String>() {

@Override

public void onCompleted() {

}

@Override

public void onError(Throwable e) {

e.printStackTrace();

}

@Override

public void onNext(String s) {

Log.d(TAG, s);

}

});

Subscribers

ConnectableObservable<Integer> connectableObservable = Observable.range(0, 5).publish();connectableObservable.filter(integer -> integer % 2 == 0)

.map(integer -> integer.toString())

.subscribe(string -> {Log.d(TAG, "even " +string);

});

connectableObservable.filter((integer -> (integer % 2 != 0)))

.map(integer -> integer.toString())

.subscribe(new Action1<String>() {@Override

public void call(String s) {

Log.d(TAG, "odd "+s);

}

});

connectableObservable.connect();

Conclusion

The old time

Conclusion

class DownloadTask extends AsyncTask<String, Void, File> {

protected File doInBackground(String... args) {

final String url = args[0];

try {

byte[] fileContent = downloadFile(url);

File file = writeToFile(fileContent);

return file;

} catch (Exception e) {

// How to show alert error to user ???}

}

protected void onPostExecute(File file) {

Context context = getContext(); // Memory leak ???Toast.makeText(context,

"Downloaded: " + file.getAbsolutePath(),

Toast.LENGTH_SHORT)

.show();

}

}

Model View Presenter

Source code

https://github.com/toidv/MVP-Clean-Architecture

Q & A

THANK YOU!