RxJava - Buffering

Buffering operator allows to gather items emitted by an Observable into a list or bundles and emit those bundles instead of items. In the example below, we've created an Observable to emit 9 items and using buffering, 3 items will be emitted together.

Example - Usage of Buffering Operator

ObservableTester.java

package com.tutorialspoint;

import java.util.List;
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())
         .buffer(3)
         .subscribe(new Observer<List<Integer>>() {
            @Override
            public void onSubscribe(Disposable d) {
               System.out.println("Subscribed");
            }
            @Override
            public void onNext(List<Integer> integers) {
               System.out.println("onNext: ");
               for (Integer value : integers) {
                  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!