@Test public void test01() { List list = new ArrayList(); list.add("张三丰"); list.add(100); System.out.println(list); }
@Test public void test02() { List<String> list = new ArrayList<>(); list.add("张三丰"); list.add(100); //错误,没法向String泛型的集合中添加int元素,编译时就直接没法经过 System.out.println(list); }