DistinctExample.java

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 * Copyright (c) 2015 Christos Froussios
 *
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 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
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package itrx.chapter2.reducing;

import java.util.Arrays;

import org.junit.Test;

import rx.Observable;
import rx.observers.TestSubscriber;

public class DistinctExample {
	
	public void exampleDistinct() {
		Observable<Integer> values = Observable.create(o -> {
		    o.onNext(1);
		    o.onNext(1);
		    o.onNext(2);
		    o.onNext(3);
		    o.onNext(2);
		    o.onCompleted();
		});

		values
		    .distinct()
		    .subscribe(
		        v -> System.out.println(v),
		        e -> System.out.println("Error: " + e),
		        () -> System.out.println("Completed")
		    );
		
		// 1
		// 2
		// 3
		// Completed
	}
	
	public void exampleDistinctKey() {
		Observable<String> values = Observable.create(o -> {
		    o.onNext("First");
		    o.onNext("Second");
		    o.onNext("Third");
		    o.onNext("Fourth");
		    o.onNext("Fifth");
		    o.onCompleted();
		});

		values
		    .distinct(v -> v.charAt(0))
		    .subscribe(
		        v -> System.out.println(v),
		        e -> System.out.println("Error: " + e),
		        () -> System.out.println("Completed")
		    );
		
		// First
		// Second
		// Third
		// Completed
	}
	
	public void exampleDistinctUntilChanged() {
		Observable<Integer> values = Observable.create(o -> {
		    o.onNext(1);
		    o.onNext(1);
		    o.onNext(2);
		    o.onNext(3);
		    o.onNext(2);
		    o.onCompleted();
		});

		values
		    .distinctUntilChanged()
		    .subscribe(
		        v -> System.out.println(v),
		        e -> System.out.println("Error: " + e),
		        () -> System.out.println("Completed")
		    );
		
		// 1
		// 2
		// 3
		// 2
		// Completed
	}
	
	public void exampleDistinctUntilChangedKey() {
		Observable<String> values = Observable.create(o -> {
		    o.onNext("First");
		    o.onNext("Second");
		    o.onNext("Third");
		    o.onNext("Fourth");
		    o.onNext("Fifth");
		    o.onCompleted();
		});

		values
		    .distinctUntilChanged(v -> v.charAt(0))
		    .subscribe(
		            v -> System.out.println(v),
		            e -> System.out.println("Error: " + e),
		            () -> System.out.println("Completed")
		        );
		
		// First
		// Second
		// Third
		// Fourth
		// Completed
	}
	
	
	//
	// Tests
	//

	@Test
	public void testDistinct() {
		TestSubscriber<Integer> tester = new TestSubscriber<Integer>();
		
		Observable<Integer> values = Observable.create(o -> {
		    o.onNext(1);
		    o.onNext(1);
		    o.onNext(2);
		    o.onNext(3);
		    o.onNext(2);
		    o.onCompleted();
		});

		values
		    .distinct()
		    .subscribe(tester);
		
		tester.assertReceivedOnNext(Arrays.asList(1,2,3));
		tester.assertTerminalEvent();
		tester.assertNoErrors();
	}
	
	@Test
	public void testDistinctKey() {
		TestSubscriber<String> tester = new TestSubscriber<String>();
		
		Observable<String> values = Observable.create(o -> {
		    o.onNext("First");
		    o.onNext("Second");
		    o.onNext("Third");
		    o.onNext("Fourth");
		    o.onNext("Fifth");
		    o.onCompleted();
		});

		values
		    .distinct(v -> v.charAt(0))
		    .subscribe(tester);
		
		tester.assertReceivedOnNext(Arrays.asList("First", "Second", "Third"));
		tester.assertTerminalEvent();
		tester.assertNoErrors();
	}
	
	@Test
	public void testDistinctUntilChanged() {
		TestSubscriber<Integer> tester = new TestSubscriber<Integer>();
		
		Observable<Integer> values = Observable.create(o -> {
		    o.onNext(1);
		    o.onNext(1);
		    o.onNext(2);
		    o.onNext(3);
		    o.onNext(2);
		    o.onCompleted();
		});

		values
		    .distinctUntilChanged()
		    .subscribe(tester);
		
		tester.assertReceivedOnNext(Arrays.asList(1,2,3,2));
		tester.assertTerminalEvent();
		tester.assertNoErrors();
	}
	
	@Test
	public void testDistinctUntilChangedKey() {
		TestSubscriber<String> tester = new TestSubscriber<String>();
		
		Observable<String> values = Observable.create(o -> {
		    o.onNext("First");
		    o.onNext("Second");
		    o.onNext("Third");
		    o.onNext("Fourth");
		    o.onNext("Fifth");
		    o.onCompleted();
		});

		values
		    .distinctUntilChanged(v -> v.charAt(0))
		    .subscribe(tester);
		
		tester.assertReceivedOnNext(Arrays.asList("First", "Second", "Third", "Fourth"));
		tester.assertTerminalEvent();
		tester.assertNoErrors();
	}

}