java.util.ArrayDeque#iterator ( )源码实例Demo

/**
 * iterator.remove() removes current element
 */
public void testIteratorRemove() {
    final ArrayDeque q = new ArrayDeque();
    final Random rng = new Random();
    for (int iters = 0; iters < 100; ++iters) {
        int max = rng.nextInt(5) + 2;
        int split = rng.nextInt(max - 1) + 1;
        for (int j = 1; j <= max; ++j)
            q.add(new Integer(j));
        Iterator it = q.iterator();
        for (int j = 1; j <= split; ++j)
            assertEquals(it.next(), new Integer(j));
        it.remove();
        assertEquals(it.next(), new Integer(split + 1));
        for (int j = 1; j <= split; ++j)
            q.remove(new Integer(j));
        it = q.iterator();
        for (int j = split + 1; j <= max; ++j) {
            assertEquals(it.next(), new Integer(j));
            it.remove();
        }
        assertFalse(it.hasNext());
        assertTrue(q.isEmpty());
    }
}
 

/**
 * iterator.remove() removes current element
 */
public void testIteratorRemove() {
    final ArrayDeque q = new ArrayDeque();
    final Random rng = new Random();
    for (int iters = 0; iters < 100; ++iters) {
        int max = rng.nextInt(5) + 2;
        int split = rng.nextInt(max - 1) + 1;
        for (int j = 1; j <= max; ++j)
            q.add(new Integer(j));
        Iterator it = q.iterator();
        for (int j = 1; j <= split; ++j)
            assertEquals(it.next(), new Integer(j));
        it.remove();
        assertEquals(it.next(), new Integer(split + 1));
        for (int j = 1; j <= split; ++j)
            q.remove(new Integer(j));
        it = q.iterator();
        for (int j = split + 1; j <= max; ++j) {
            assertEquals(it.next(), new Integer(j));
            it.remove();
        }
        assertFalse(it.hasNext());
        assertTrue(q.isEmpty());
    }
}
 

/**
 * Iterator iterates through all elements
 */
public void testIterator() {
    ArrayDeque q = populatedDeque(SIZE);
    Iterator it = q.iterator();
    int i;
    for (i = 0; it.hasNext(); i++)
        assertTrue(q.contains(it.next()));
    assertEquals(i, SIZE);
    assertIteratorExhausted(it);
}
 

/**
 * Iterator ordering is FIFO
 */
public void testIteratorOrdering() {
    final ArrayDeque q = new ArrayDeque();
    q.add(one);
    q.add(two);
    q.add(three);
    int k = 0;
    for (Iterator it = q.iterator(); it.hasNext();) {
        assertEquals(++k, it.next());
    }

    assertEquals(3, k);
}
 

void checkToArray(ArrayDeque q) {
    int size = q.size();
    Object[] o = q.toArray();
    assertEquals(size, o.length);
    Iterator it = q.iterator();
    for (int i = 0; i < size; i++) {
        Integer x = (Integer) it.next();
        assertEquals((Integer)o[0] + i, (int) x);
        assertSame(o[i], x);
    }
}
 

void checkToArray2(ArrayDeque q) {
    int size = q.size();
    Integer[] a1 = (size == 0) ? null : new Integer[size - 1];
    Integer[] a2 = new Integer[size];
    Integer[] a3 = new Integer[size + 2];
    if (size > 0) Arrays.fill(a1, 42);
    Arrays.fill(a2, 42);
    Arrays.fill(a3, 42);
    Integer[] b1 = (size == 0) ? null : (Integer[]) q.toArray(a1);
    Integer[] b2 = (Integer[]) q.toArray(a2);
    Integer[] b3 = (Integer[]) q.toArray(a3);
    assertSame(a2, b2);
    assertSame(a3, b3);
    Iterator it = q.iterator();
    for (int i = 0; i < size; i++) {
        Integer x = (Integer) it.next();
        assertSame(b1[i], x);
        assertEquals(b1[0] + i, (int) x);
        assertSame(b2[i], x);
        assertSame(b3[i], x);
    }
    assertNull(a3[size]);
    assertEquals(42, (int) a3[size + 1]);
    if (size > 0) {
        assertNotSame(a1, b1);
        assertEquals(size, b1.length);
        for (int i = 0; i < a1.length; i++) {
            assertEquals(42, (int) a1[i]);
        }
    }
}
 

/**
 * Iterator iterates through all elements
 */
public void testIterator() {
    ArrayDeque q = populatedDeque(SIZE);
    Iterator it = q.iterator();
    int i;
    for (i = 0; it.hasNext(); i++)
        assertTrue(q.contains(it.next()));
    assertEquals(i, SIZE);
    assertIteratorExhausted(it);
}
 

/**
 * Iterator ordering is FIFO
 */
public void testIteratorOrdering() {
    final ArrayDeque q = new ArrayDeque();
    q.add(one);
    q.add(two);
    q.add(three);
    int k = 0;
    for (Iterator it = q.iterator(); it.hasNext();) {
        assertEquals(++k, it.next());
    }

    assertEquals(3, k);
}