Observables

Operators

Subjects

Schedulers

Miscellaneous

RxJava Useful Resources

RxJava - Filtering Operators

Quiz

Following are the operators which are used to selectively emit item(s) from an Observable.

Sr.No.	Operator & Description
1	debounce Emits items only when timeout occurs without emiting another item.
2	distinct Emits only unique items.
3	elementAt emit only item at n index emitted by an Observable.
4	filter Emits only those items which pass the given predicate function.
5	first Emits the first item or first item which passed the given criteria.
6	ignoreElements Do not emits any items from Observable but marks completion.
7	last Emits the last element from Observable.
8	sample Emits the most recent item with given time interval.
9	skip Skips the first n items from an Observable.
10	skipLast Skips the last n items from an Observable.
11	take takes the first n items from an Observable.
12	takeLast takes the last n items from an Observable.

Example - Taking First two items

ObservableTester.java

package com.tutorialspoint;

import io.reactivex.rxjava3.core.Observable;

// Using take operator to filter items
public class ObservableTester  {
   public static void main(String[] args) { 
      String[] letters = {"a", "b", "c", "d", "e", "f", "g"};
      final StringBuilder result = new StringBuilder();
      Observable<String> observable = Observable.fromArray(letters);
      observable
         .take(2)
         .subscribe( letter -> result.append(letter));
      System.out.println(result);
   }
}

Output

Compile and Run the code to verify the following output −

ab

Example - Skipping First two items

ObservableTester.java

package com.tutorialspoint;

import io.reactivex.rxjava3.core.Observable;

//Using map operator to tranform an item emitted
public class ObservableTester  {
   public static void main(String[] args) { 
      String[] letters = {"a", "b", "c", "d", "e", "f", "g"};
      final StringBuilder result = new StringBuilder();
      Observable<String> observable = Observable.fromArray(letters);
      observable
         .skip(2)
         .subscribe( letter -> result.append(letter));
      System.out.println(result);
   }
}

Output

Compile and Run the code to verify the following output −

cdefg

Print Page