ForEachExample.java

/*******************************************************************************
 * Copyright (c) 2015 Christos Froussios
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 *******************************************************************************/
package itrx.chapter3.leaving;

import static org.junit.Assert.*;

import java.lang.Thread.State;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

import org.junit.Test;

import rx.Observable;
import rx.schedulers.Schedulers;
import rx.schedulers.TestScheduler;

public class ForEachExample {

	public void exampleObservableForEach() {
		Observable<Long> values = Observable.interval(100, TimeUnit.MILLISECONDS);

		values
		    .take(5)
		    .forEach(
		        v -> System.out.println(v));
		System.out.println("Subscribed");
		
		// Subscribed
		// 0
		// 1
		// 2
		// 3
		// 4
	}
	
	public void exampleBlockingForEach() {
		Observable<Long> values = Observable.interval(100, TimeUnit.MILLISECONDS);

		values
		    .take(5)
		    .toBlocking()
		    .forEach(
		        v -> System.out.println(v));
		System.out.println("Subscribed");
		
		// 0
		// 1
		// 2
		// 3
		// 4
		// Subscribed
	}
	
	public void exampleBlockingForEachError() {
		Observable<Long> values = Observable.error(new Exception("Oops"));

		try {
		    values
		        .take(5)
		        .toBlocking()
		        .forEach(
		            v -> System.out.println(v));
		}
		catch (Exception e) {
		    System.out.println("Caught: " + e.getMessage());
		}
		System.out.println("Subscribed");
		
		// Caught: java.lang.Exception: Oops
		// Subscribed
	}
	
	
	// 
	// Tests
	//
	
	@Test
	public void testObservableForEach() {
		List<Long> received = new ArrayList<>();
		TestScheduler scheduler = Schedulers.test();
		
		Observable<Long> values = Observable.interval(100, TimeUnit.MILLISECONDS, scheduler);

		values
		    .take(5)
		    .forEach(
		        i -> received.add(i));
		received.add(-1L); // Mark that forEach statement returned
		
		assertEquals(received, Arrays.asList(-1L));
		scheduler.advanceTimeBy(1, TimeUnit.SECONDS);
		assertEquals(received, Arrays.asList(-1L, 0L, 1L, 2L, 3L, 4L));
	}
	
	@Test
	public void testBlockingForEach() throws InterruptedException {
		List<Long> received = new ArrayList<>();
		TestScheduler scheduler = Schedulers.test();
		
		Observable<Long> values = Observable.interval(100, TimeUnit.MILLISECONDS, scheduler);

		// Blocking call on new thread
		Thread thread = new Thread(() -> {
			values
			    .take(5)
			    .toBlocking()
			    .forEach(
		    		i -> received.add(i));
			received.add(-1L); // Mark that forEach statement returned
			
		});
		thread.start();
		
		assertEquals(received, Arrays.asList());
		// Wait for blocking call to block before producing values
		while (thread.getState() != State.WAITING)
			Thread.sleep(1);
		scheduler.advanceTimeBy(1, TimeUnit.SECONDS);
		// Wait for processing to complete
		thread.join(50);
		assertEquals(received, Arrays.asList(0L, 1L, 2L, 3L, 4L, -1L));
	}
	
	@Test(expected = Exception.class)
	public void testBlockingForEachError() {
		Observable<Long> values = Observable.error(new Exception("Oops"));

	    values
	        .take(5)
	        .toBlocking()
	        .forEach(
	            v -> {});
	}

}