RxJava Tutorial on RxJava Conditional Operators
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following are the operators which evaluates one or multiple observables or items emitted.

sr.no. operator & description
1

all

evaluates all items emitted to meet given criteria.
2

amb

emits all items from the first observable only given multiple observables.
3

contains

checks if an observable emits a particular item or not.
4

defaultifempty

emits default item if observable do not emit anything.
5

sequenceequal

checks if two observables emit the same sequence of items.
6

skipuntil

discards items emitted by first observable until a second observable emits an item.
7

skipwhile

discard items emitted by an observable until a given condition becomes false.
8

takeuntil

discards items emitted by an observable after a second observable emits an item or terminates.
9

takewhile

discard items emitted by an observable after a specified condition becomes false.

conditional operator example

create the following java program using any editor of your choice in, say, c:\> rxjava.

observabletester.java

import io.reactivex.observable;
//using defaultifempty operator to operate on an observable
public class observabletester  {
   public static void main(string[] args) {    
      final stringbuilder result = new stringbuilder();
      observable.empty()
      .defaultifempty("no data")
      .subscribe(s -> result.append(s));
      system.out.println(result);
      string[] letters = {"a", "b", "c", "d", "e", "f", "g"};
      final stringbuilder result1 = new stringbuilder();
      observable.fromarray(letters)
      .firstelement()
      .defaultifempty("no data")   
      .subscribe(s -> result1.append(s));
      system.out.println(result1);
   }
}

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 −

no data
a
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