绕过泛型，通过反射把 String 添加到 List < Integer > 中

public class ArrayListDemo {
 
    public static void main(String[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        List<Integer> list = new ArrayList<Integer>();
 
        list.add(1);
        // list.add("hello");不能添加
      
        Class clzz = list.getClass();
        Method method = clzz.getMethod("add",Object.class);
        method.invoke(list,"hello");

        System.out.println(list);
    }
}