Reactive Programming on Android with RxJava_468 x 60 copy 2.png

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RxJava

Since its inception in 2012, RxJava has slowly gained in popularity for enabling reactive programming on Android. It is now deemed as the go-to and leading reactive library. Many companies have adopted the reactive way of programming, including Google, with its release of Android Architecture Components, which has many reactive elements in its design.

In this course, you will learn the fundamental principles of RxJava which will serve as a foundation for experienced Android developers who are new to the library and want to start integrating it into their apps.

Reactive Programming with RxJava

Which of the following is the RxJava construct for adding synchronicity?


Which of the following is the RxJava construct for adding synchronicity?

It is advised to place it first in the operator chain.

It affects the upstream source `Observable`.

Which of the following is **true** about the `.observeOn()` operator?

Which of the following is true about the <code>.observeOn()</code> operator?

Which of the following schedulers should replace `X` in the code below if we want to schedule work on the current thread?

```java
Observable<Integer> observable = Observable.create(source -> {
 System.out.println("In subscribe");
 source.onNext(1);
 source.onNext(2);
 source.onNext(3);
 });

observable.subscribeOn(X) // schedule work on current thread
 .subscribe(value -> System.out.println(value));
```

Which of the following schedulers should replace <code>X</code> in the code below if we want to schedule work on the current thread?
<pre><code class="language-java">Observable&lt;Integer&gt; observable = Observable.create(source -&gt; {
 System.out.println(&quot;In subscribe&quot;);
 source.onNext(1);
 source.onNext(2);
 source.onNext(3);
 });

observable.subscribeOn(X) // schedule work on current thread
 .subscribe(value -&gt; System.out.println(value));
</code></pre>

**(True or False)** When using `Observable.create()`, it is valid to call `onNext()`, `onComplete()` or `onError()` from different threads.

(True or False) When using <code>Observable.create()</code>, it is valid to call <code>onNext()</code>, <code>onComplete()</code> or <code>onError()</code> from different threads.

The user's name is displayed on the screen.

The app crashes with a `CalledFromWrongThreadException`.

What is the output of the code below?
```java
// `userObservable` retrieves a User object over the network
Observable<User> userObservable = getUser(123); 
userObservable.subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(user -> textView.setText(user.getName()));
```

What is the output of the code below?
<pre><code class="language-java">// `userObservable` retrieves a User object over the network
Observable&lt;User&gt; userObservable = getUser(123); 
userObservable.subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(user -&gt; textView.setText(user.getName()));
</code></pre>

Take this short quiz to test your understanding of multithreading.

Getting Started

Part 1: RxJava Basics

Reactive Programming

RxJava Core Components

Operators

Multithreading

Part 2: RxJava Advanced

Reactive Modeling on Android

Backpressure

Error Handling

Conclusion

Quiz