RxJava - Windowing

Windowing operator works similar to buffer operator but it allows to gather items emitted by an Observable into another observable instead of collection and emit those Observables instead of collections. In the example below, we've created an Observable to emit 9 items and using window operator, 3 Observable will be emitted together.

Example - Usage of Windowing Operator

ObservableTester.java

package com.tutorialspoint;

import java.util.concurrent.TimeUnit;

import io.reactivex.rxjava3.core.Observable;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.schedulers.Schedulers;

public class ObservableTester {
   public static void main(String[] args) throws InterruptedException {
      Observable<Integer> observable = Observable.just(1, 2, 3, 4,
         5, 6, 7, 8, 9);

      observable.subscribeOn(Schedulers.io())
         .delay(2, TimeUnit.SECONDS, Schedulers.io())
         .window(3)
         .subscribe(new Observer<Observable<Integer>>() {
            @Override
            public void onSubscribe(Disposable d) {
               System.out.println("Subscribed");
            }
            @Override
            public void onNext(Observable<Integer> integers) {
               System.out.println("onNext: ");
               integers.subscribe(value -> System.out.println(value));
            }
            @Override
            public void onError(Throwable e) {
               System.out.println("Error");
            }

            @Override
            public void onComplete() {
               System.out.println("Done! ");
            }
         });
      Thread.sleep(3000);
   }
}

Output

Compile and Run the code to verify the following output −

Subscribed
onNext: 
1
2
3
onNext: 
4
5
6
onNext: 
7
8
9
Done!