One shouldn't use 2 different naming conventions. Either lower_underscore or lowerCamelCase. :)

Yep, this should be mentioned in description.

I agree - lots of kyu 8 kata's were harder than this one.

Thank you for advices. I wanted to try and make any kata just to see how it works. I will read all your advices, see more examples and I will try again in 6 months (I've just started java course so maybe by then I'll be able to do it right).

There's a tiny issue with java tests. The wrong-result-message is reversed. For exemple, if I lose "o" in "Hello", I get a message:
expected:<Hell[] Riley!> but was:<Hell[o] Riley!>
It should be:
expected:<Hell[o] Riley!> but was:<Hell[] Riley!>
isn't it? :)

Dayum, I forgot to delete String allTogether = ""; , it is useless here...

10 months after newsh's post - same story. I noticed that the tests are like this:

assertTrue(Arrays.equals(new int[] {2,4,6}, EvenNumbers.divisibleBy(new int[] {1,2,3,4,5,6},2)));

Method input: (int[], int) Method output: int[];

There was no way to make it work with long values so I did the same as newsh did - I changed all "long" types to "int", to match my method with those tests.

However...
Is it supposed to be a tricky one or is it a mistake?
If it is supposed to be this way - maybe the description should mention that it contains an additional problem to solve?

Awesome! The best example to start "my great regex adventure" - very simple but encourages to go deeper into those mysterious expressions. :)