Learning RxJava - Second Edition

collect()

When none of the collection operators can do what you need, you can always use the collect() operator to specify a different type to collect items into.

For instance, there is no toSet() operator to collect emissions in a Set<T>, but you can quickly use collect(Callable<U> initialValueSupplier, BiConsumer<U,T> collector) to effectively do this.

Let's say you need to collect String values in a Set<String> implementation. To accomplish that, you can specify the first argument—the function that produces an initial value of the Set<String> implementation you would like to use, and the second argument—the function that is going to collect the values (whatever you need to collect) in that Set<String> implementation you have chosen. ...