RxJava examples using Java 8 Lambda. Examples include zip, map, take, filter, reduce

RxJavaExamples.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import rx.Observable;
import rx.Observer;
import rx.functions.Func2;

public class RxJavaExamples {

	public static void main(String[] args) {
        new RxJavaExamples().zip();
        
        new RxJavaExamples().zip2();
        
        new RxJavaExamples().map();	    
        
        new RxJavaExamples().take();		
        
        new RxJavaExamples().filter();
        
        new RxJavaExamples().reduce();	
	}
	
	
	
	
	  //This does not use lambda. See zip2 for use of lambda.
	  public void zip() {
		Observable<Integer> obs1 = Observable.from(Arrays.asList(1, 3, 5, 7, 9));
		Observable<Integer> obs2 = Observable.from(Arrays.asList(2, 4, 6));
		
	    Observable<List<Integer>> obs = Observable.zip(obs1, obs2, new Func2<Integer, Integer, List<Integer>>() {
	        public List<Integer> call(Integer value1, Integer value2) {
	        	List<Integer> list = new ArrayList<Integer>();
	        	list.add(value1);
	        	list.add(value2);
	        	
	        	return list;
	        }
	    });
		
	    obs.subscribe(new Observer<List<Integer>>() {
	    	public void onCompleted() {
	    		System.out.println("completed");
	    	}

		    public void onError(Throwable e) {
		    	System.out.println("failure");
		    }

		    public void onNext(List<Integer> value) {
		    	System.out.println("onnext=" + value);
		    }
	    });
	    
	  }

	  
	  
	  
	   public void zip2() {
	        Observable<Integer> obs1 = Observable.from(1, 3, 5, 7, 9);
	        Observable<Integer> obs2 = Observable.from(2, 4, 6);
	        
	        Observable<List<Integer>> obs = Observable.zip(obs1, obs2, (value1, value2) -> {
                List<Integer> list = new ArrayList<Integer>();
                list.add(value1);
                list.add(value2);
                
                return list;
	        });
	        
	        obs.subscribe((value) -> {
	              System.out.println("SubscribeValue = " + value);            
	        });
	   }
	   
	   
	  
	   
	  // MapValue = 1
	  // SubscribeValue = 1aaa
	  // MapValue = 2
	  // SubscribeValue = 2aaa
	  // MapValue = 3
	  // SubscribeValue = 3aaa
	  private void map() {
	      Observable<Integer> obs = Observable.from(1, 2, 3);
	      
	      Observable<String> map = obs.map(value -> {
              System.out.println("MapValue = " + value);	          
	          return value + "aaa";
	      });
	      
	      map.subscribe((value) -> {
              System.out.println("SubscribeValue = " + value);	          
	      });
	  }
	  
	  
	  
	  
	  
	  

	  //one
	  //two
	  private void take() {
	      Observable<String> obs = Observable.from("one",  "two",  "three");
	      Observable<String> take2 = obs.take(2);
          
          take2.subscribe(arg ->  {
              System.out.println(arg); 
          });	      
	      
	  }
	  
	  

	  
	  //SubscribeValue = 1
	  //SubscribeValue = 2
	  //SubscribeValue = 3
	  private void filter() {
	      Observable.from(1, 2, 3, 4, 5)
          .filter(v -> { 
              return v < 4;
          })
          .subscribe(value -> {
              System.out.println("SubscribeValue: " + value);
          });
	  }
	  

	  
	  
	  
	  // reduce-seed = 1
	  // reduce-value = 2
	  //
	  // reduce-seed = 3 (from 1 + 2)
	  // reduce-value = 3
	  //
	  // reduce-seed = 6 (from 3 + 3)
	  // reduce-value = 4
	  //
	  // reduce-seed = 10 (from 6 + 4)
	  // reduce-value = 5
	  //
	  // map-v = 15 (from 10 + 5)
	  // subscribe-value = MapValue: 15
	  private void reduce() {
	      Observable.from(1, 2, 3, 4, 5)
	      .reduce((seed, value) -> {
	          // sum all values from the sequence
	          System.out.println("reduce-seed = " + seed);
              System.out.println("reduce-value = " + value);	          
	          return seed + value;
	      })
	      .map(v -> {
	          System.out.println("map-v = " + v);
	          return "MapValue: " + v;
	      })
	      .subscribe(value -> {
	          System.out.println("subscribe-value = " + value);
	      });     
	  }
	

}