public final class CompositeDisposable
extends Object
implements Disposable, io.reactivex.internal.disposables.DisposableContainer

import io.reactivex.Maybe;
import io.reactivex.Single;
import io.reactivex.disposables.CompositeDisposable;
import io.reactivex.disposables.Disposable;
import io.reactivex.observers.DisposableMaybeObserver;
import io.reactivex.observers.DisposableSingleObserver;
import io.reactivex.schedulers.Schedulers;

import java.util.concurrent.TimeUnit;

public class ObservableTester  {
   public static void main(String[] args)  throws InterruptedException {    
      CompositeDisposable compositeDisposable = new CompositeDisposable();

      //Create an Single observer 
      Disposable disposableSingle = Single.just("Hello World")
      .delay(2, TimeUnit.SECONDS, Schedulers.io())
      .subscribeWith(
      new DisposableSingleObserver() {
         @Override
         public void onError(Throwable e) {
            e.printStackTrace();
         }

         @Override
         public void onSuccess(String value) {
            System.out.println(value);
         }
      }); 

      //Create an observer
      Disposable disposableMayBe = Maybe.just("Hi")
      .delay(2, TimeUnit.SECONDS, Schedulers.io())
      .subscribeWith(new DisposableMaybeObserver() {
         @Override
         public void onError(Throwable e) { 
            e.printStackTrace();
         }

         @Override
         public void onSuccess(String value) {
            System.out.println(value);
         }

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

      Thread.sleep(3000);

      compositeDisposable.add(disposableSingle);
      compositeDisposable.add(disposableMayBe);

      //start observing
      compositeDisposable.dispose();
   }
}

C:\RxJava>javac ObservableTester.java

C:\RxJava>java ObservableTester

Hello World
Hi