This example will generate odd numbers from a given range. In the snippets below all odd numbers between 1 and 10 will be displayed.
Java 8
The Intstream.rangeClosed will return a range from 1 to 10. Next, a lambda expression will be used to create a java predicate that will return true if the number is odd. Passing it to IntStream.filter it will return all odd numbers for the given range.
@Test
public void generate_odd_numbers_in_range_java8() {
Set<Integer> oddNumbers = IntStream.rangeClosed(1, 10)
.filter(n -> n % 2 != 0).boxed().collect(Collectors.toSet());
logger.info(oddNumbers);
assertThat(
oddNumbers,
contains(new Integer(1), new Integer(3), new Integer(5),
new Integer(7), new Integer(9)));
}Output
[1, 3, 5, 7, 9]Google Guava
Using guava we will create a ContiguousSet passing in a Range from 1 to 10. We then will pass a guava predicate that will return true if the given number is odd to the Iterables.filter method to return all odd numbers within the range.
@Test
public void generate_odd_numbers_in_range_guava() {
Set<Integer> set = ContiguousSet.create(Range.closed(1, 10),
DiscreteDomain.integers());
Iterable<Integer> oddNumbers = Iterables.filter(set,
new Predicate<Integer>() {
@Override
public boolean apply(Integer input) {
return input % 2 != 0;
}
});
logger.info(oddNumbers);
assertThat(
oddNumbers,
contains(new Integer(1), new Integer(3), new Integer(5),
new Integer(7), new Integer(9)));
}Output
[1, 3, 5, 7, 9]