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RxJava Useful Resources

RxJava - Combining Operators

Quiz

Following are the operators which are used to create a single Observable from multiple Observables.

Sr.No.	Operator & Description
1	and/then/when Combine item sets using Pattern and Plan intermediaries.
2	combineLatest Combine the latest item emitted by each Observable via a specified function and emit resulted item.
3	join Combine items emitted by two Observables if emitted during time-frame of second Observable emitted item.
4	merge Combines the items emitted of Observables.
5	startWith Emit a specified sequence of items before starting to emit the items from the source Observable
6	switch Emits the most recent items emitted by Observables.
7	zip Combines items of Observables based on function and emits the resulted items.

Example - Using combineLatest Operator

ObservableTester.java

package com.tutorialspoint;

import io.reactivex.rxjava3.core.Observable;

//Using combineLatest operator to combine Observables
public class ObservableTester {
   public static void main(String[] args) {    
      Integer[] numbers = { 1, 2, 3, 4, 5, 6};
      String[] letters = {"a", "b", "c", "d", "e", "f", "g"};
      final StringBuilder result = new StringBuilder();
      Observable<String> observable1 = Observable.fromArray(letters);
      Observable<Integer> observable2 = Observable.fromArray(numbers);
      Observable.combineLatest(observable1, observable2, (a,b) -> a + b)
         .subscribe( letter -> result.append(letter));
      System.out.println(result);
   }
}

Output

Compile and Run the code to verify the following output −

g1g2g3g4g5g6

Example - Using concat Operator

ObservableTester.java

package com.tutorialspoint;

import io.reactivex.rxjava3.core.Observable;

//Using concat operator to combine Observables
public class ObservableTester {
   public static void main(String[] args) {    
      Integer[] numbers = { 1, 2, 3, 4, 5, 6};
      String[] letters = {"a", "b", "c", "d", "e", "f", "g"};
      final StringBuilder result = new StringBuilder();
      Observable<String> observable1 = Observable.fromArray(letters);
      Observable<Integer> observable2 = Observable.fromArray(numbers);
      Observable.concat(observable1, observable2)
         .subscribe( letter -> result.append(letter));
      System.out.println(result);
   }
}

Output

Compile and Run the code to verify the following output −

abcdefg123456

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