@Test
public void testWithNullsLast() {
Long[] a = new Long[] {null, 5L, 1L, 3L, null, 2L, 4L, null};
Arrays.sort(a, Comparators.withNullsLast(new AscendingLongComparator()));
assertArrayEquals(new Long[] {1L, 2L, 3L, 4L, 5L, null, null, null}, a);
}
@Test
public void testNaturalOrder() {
Comparator<Long> natural = Comparators.naturalOrder();
Long[] a = new Long[] {5L, 1L, 3L, 2L, 4L, 1L};
Arrays.sort(a, natural);
assertArrayEquals(new Long[] {1L, 1L, 2L, 3L, 4L, 5L}, a);
}
@Test
public void testCompose() {
Comparator<String> nullsLast = new NullsLastStringComparator();
Comparator<String> alphabetical = new AlphabeticalStringComparator();
String[] a = new String[] {null, "b", "d", null, "a", null, "c"};
Arrays.sort(a, Comparators.compose(nullsLast, alphabetical));
assertArrayEquals(new String[] {"a", "b", "c", "d", null, null, null}, a);
}
@Test
public void testReverse() {
Comparator<Long> ascending = new AscendingLongComparator();
Long[] a = new Long[] {5L, 1L, 3L, 2L, 4L, 1L};
Arrays.sort(a, ascending);
assertArrayEquals(new Long[] {1L, 1L, 2L, 3L, 4L, 5L}, a);
Comparator<Long> descending = Comparators.reverse(ascending);
Arrays.sort(a, descending);
assertArrayEquals(new Long[] {5L, 4L, 3L, 2L, 1L, 1L}, a);
}