public void clear() {
        for (int i = 0; i < sections.length; i++) {
            sections[i].clear();
        }
    }
@Test
    public void testClear() {
        ConcurrentLongHashMap<String> map = ConcurrentLongHashMap.<String>newBuilder()
                .expectedItems(2)
                .concurrencyLevel(1)
                .autoShrink(true)
                .mapIdleFactor(0.25f)
                .build();
        assertTrue(map.capacity() == 4);

        assertNull(map.put(1, "v1"));
        assertNull(map.put(2, "v2"));
        assertNull(map.put(3, "v3"));

        assertTrue(map.capacity() == 8);
        map.clear();
        assertTrue(map.capacity() == 4);
    }