java.util.concurrent.ArrayBlockingQueue#clear ( )源码实例Demo

/**
 * clear removes all elements
 */
public void testClear() {
    int size = ThreadLocalRandom.current().nextInt(1, 5);
    ArrayBlockingQueue q = populatedQueue(size, size, 2 * size, false);
    int capacity = size + q.remainingCapacity();
    q.clear();
    assertTrue(q.isEmpty());
    assertEquals(0, q.size());
    assertEquals(capacity, q.remainingCapacity());
    q.add(one);
    assertFalse(q.isEmpty());
    assertTrue(q.contains(one));
    q.clear();
    assertTrue(q.isEmpty());
}
 

public void clear_willClearItrs() {
    boolean fair = rnd.nextBoolean();
    int capacity = rnd.nextInt(2, 10);
    ArrayBlockingQueue q = new ArrayBlockingQueue(capacity, fair);
    randomizePutIndex(q);
    List<Iterator> its = new ArrayList<>();
    for (int i = 0; i < capacity; i++)
        assertTrue(q.add(i));
    assertNull(itrs(q));
    for (int i = 0; i < capacity; i++) {
        its.add(q.iterator());
        assertEquals(trackedIterators(q), its);
        q.poll();
        q.add(capacity + i);
    }
    q.clear();
    assertNull(itrs(q));
    int j = 0;
    for (Iterator it : its) {
        assertTrue(isDetached(it));
        if (rnd.nextBoolean()) assertTrue(it.hasNext());
        if (rnd.nextBoolean()) {
            assertEquals(it.next(), j);
            assertIteratorExhausted(it);
        }
        j++;
    }
}
 

/**
 * clear removes all elements
 */
public void testClear() {
    ArrayBlockingQueue q = populatedQueue(SIZE);
    q.clear();
    assertTrue(q.isEmpty());
    assertEquals(0, q.size());
    assertEquals(SIZE, q.remainingCapacity());
    q.add(one);
    assertFalse(q.isEmpty());
    assertTrue(q.contains(one));
    q.clear();
    assertTrue(q.isEmpty());
}