CODEWITHSUNDEEP
androidandroid-asynctaskrx-java
panbacuh
panbacuh

Reputation: 632

AndroidRX - run method in background

I created simple activity with infinity progres bar, and I'am trying to run time consuming method using RxJava to prevent UI thread from blocking, but everytime UI thread is blocked. I think my solution has problem with emitting Observable. Can anyone help me? I'am begginer in RX. 

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

public void doSomething(View view) {
    doHeavyStuff()
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .doOnNext(new Action1() {
                @Override
                public void call(Object o) {
                    Toast.makeText(getApplicationContext(), "FINISHED", Toast.LENGTH_SHORT).show();
                }
            })
            .subscribe();
}

private Observable doHeavyStuff() {
    for (int i = 0; i < 999999999; i++) {
        for (int j = 0; j < 2; j++) {
        }
    }
    return Observable.just(1);

}

Upvotes: 23

Views: 16179

Answers (5)

vovahost
vovahost

Reputation: 36049

With RxJava2 a possible solution is:

Version with lambdas:

Single.fromCallable(() -> loadInBackground())
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe((resultObject) -> { updateUi(resultObject) });

Version without lambdas:

Single.fromCallable(new Callable<Object>() {
    @Override
    public Object call() throws Exception {
        return loadInBackground();
    }
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<Object>() {
    @Override
    public void accept(Object resultObject) throws Exception {
        updateUi(resultObject);
    }
 });

Example methods used above:

private Object loadInBackground() {
    // some heavy load code
    return resultObject;
}

private void updateUi(Object resultObject) {
    // update your Views here
}

Upvotes: 36

Jaydeep Khambhayta
Jaydeep Khambhayta

Reputation: 5329

kotlin use below code to work in background 

 Single.fromCallable {
                  // method that run in background

          }
           .subscribeOn(Schedulers.io())
           .observeOn(AndroidSchedulers.mainThread())
           .subscribe()

Upvotes: 12

krp
krp

Reputation: 2247

Your doHeavyStuff() executes computation on calling thread, you just wrap your result into Observable. In order to wrap computation into observable you should use defer 

Observable.defer(new Func0<Observable<Integer>>() {
    @Override
    public Observable<Integer> call() {
        return Observable.just(doHeavyStuff());
    }
});

then you can specify threads by subscribeOn and observeOn methods

Upvotes: 10

Mikelis Kaneps
Mikelis Kaneps

Reputation: 4584

According to docs

Deprecated: fromFunc0 Unnecessary now that Func0 extends Callable. Just call fromCallable(java.util.concurrent.Callable) instead.

So you could make the call in this way:

Observable.fromCallable(new Callable<Object>() {
            @Override
            public Object call() throws Exception {
                return someMethod();
            }
        }).subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread()).subscribe(new Action1<Object>() {
                    @Override
                    public void call(Object object) {

                    }
                });

Upvotes: 11

Danila Grigorenko
Danila Grigorenko

Reputation: 423

Also, you can use RxJavaAsyncUtil:

compile 'io.reactivex:rxjava-async-util:0.21.0'

Code:

Observable.fromFunc0(() -> doHeavyStuff())

Upvotes: 1

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