问方法assertEquals(Object，Object)对于类型是不明确的？

EN

@Test
public void testAddAndGet1() {
    ArrayList<Integer> list = new ArrayList<Integer>();

    list.add(42);
    list.add(-3);
    list.add(17);
    list.add(99);
    assertEquals(42, list.get(0));
    assertEquals(-3, list.get(1));
    assertEquals(17, list.get(2));
    assertEquals(99, list.get(3));

    assertEquals("second attempt", 42, list.get(0));   // make sure I can get them a second time
    assertEquals("second attempt", 99, list.get(3));
}