Operator - from

From

convert various other objects and data types into Observables

When you work with Observables, it can be more convenient if all of the data you mean to work with can be represented as Observables, rather than as a mixture of Observables and other types. This allows you to use a single set of operators to govern the entire lifespan of the data stream.

Iterables, for example, can be thought of as a sort of synchronous Observable; Futures, as a sort of Observable that always emits only a single item. By explicitly converting such objects to Observables, you allow them to interact as peers with other Observables.

For this reason, most ReactiveX implementations have methods that allow you to convert certain language-specific objects and data structures into Observables.

--> fromIterable

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List<Integer> list2 = new ArrayList<>();

list2.add(1);

list2.add(2);

list2.add(7);

list2.add(8);

    

Observable.fromIterable(list2).subscribe(System.out::println);

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--> fromArray

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Observable.fromArray(list2).subscribe(System.out::println);

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