RxJava - Mathematical Operators

Following are the operators which operates on entire items emitted by an Observable.

Sr.No.	Operator & Description
1	Average Evaluates averages of all items and emit the result.
2	Concat Emits all items from multiple Observable without interleaving.
3	Count Counts all items and emit the result.
4	Max Evaluates max valued item of all items and emit the result.
5	Min Evaluates min valued item of all items and emit the result.
6	Reduce Apply a function on each item and return the result.
7	Sum Evaluates sum of all items and emit the result.

Mathematical Operator Example

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

ObservableTester.java

import io.reactivex.Observable;
//Using concat operator to operate on multiple Observables
public class ObservableTester  {
   public static void main(String[] args)  throws InterruptedException {    
      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);
   }
}

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 −

abcdefg123456