Chain google collections

gistfile1.txt

public class T
{
    protected static final Predicate<String> STRING_PREDICATE = new Predicate<String>()
    {
        @Override
        public boolean apply(final String input)
        {
            return !Strings.isNullOrEmpty(input);
        }
    };

    protected static final Function<String, String> STRING_FUNCTION = new Function<String, String>()
    {

        @Override
        public String apply(final String input)
        {
            return input == null ? "" : input.trim();
        }
    };

    public static void main(String[] a)
    {
        final List<String> tokens = Lists.newArrayList(" some ", null, "stuff\t", "", " \nhere");

        final Collection filtered = transform(tokens, STRING_FUNCTION).thenFilter(STRING_PREDICATE);

        // Output, as desired: [some, stuff, here]
        System.out.println(filtered);
    }

    private static Then transform(final List<String> tokens, final Function function)
    {
        final Collection transformedCollection = Collections2.transform(tokens, function);

        return new Then(transformedCollection);
    }

    private static class Then
    {
        private Collection collection;

        public Then(final Collection collection)
        {
            this.collection = collection;
        }

        public Collection thenFilter(Predicate predicate)
        {
            return Collections2.filter(collection, predicate);
        }
    }
}