Limit a stream by a predicate

Question

Is there a Java 8 stream operation that limits a (potentially infinite) Stream until the first element fails to match a predicate?

In Java 9 we can use takeWhile as in the example below to print all the numbers less than 10.

IntStream
    .iterate(1, n -> n + 1)
    .takeWhile(n -> n < 10)
    .forEach(System.out::println);

As there is no such operation in Java 8, what's the best way of implementing it in a general way?

Answer 1

Operations takeWhile and dropWhile have been added to JDK 9. Your example code

IntStream
    .iterate(1, n -> n + 1)
    .takeWhile(n -> n < 10)
    .forEach(System.out::println);

will behave exactly as you expect it to when compiled and run under JDK 9.

JDK 9 has been released. It is available for download here: JDK 9 Releases.