The MayBe class represents deferred response. MayBe observable can emit either a single successful value or no value.

Class Declaration

Following is the declaration for io.reactivex.Single<T> class −

public abstract class Maybe<T>
   extends Object
      implements MaybeSource<T>

Protocol

Following is the sequential protocol that MayBe Observable operates −

onSubscribe (onSuccess | onError | OnComplete)?

MayBe Example

Create the following Java program using any editor of your choice in, say, C:> RxJava.

ObservableTester.java

import java.util.concurrent.TimeUnit;

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

public class ObservableTester {
   public static void main(String[] args) throws InterruptedException {
      //Create an observer
      Disposable disposable = Maybe.just("Hello World")
         .delay(2, TimeUnit.SECONDS, Schedulers.io())
         .subscribeWith(new DisposableMaybeObserver<String>() {
         @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);
      //start observing
      disposable.dispose();
   }
}

Verify the Result

Compile the class using javac compiler as follows −

C:RxJava>javac ObservableTester.java

Now run the ObservableTester as follows −

C:RxJava>java ObservableTester

It should produce the following output −

Hello World