java动态二维数组问题

import java.util.*;
public class test
{
public static void main(String[]args)
{
ArrayList al=new ArrayList();
al.add(new ArrayList());
((ArrayList)al.get(0)).add("1");
((ArrayList)al.get(0)).add("2");
((ArrayList)al.get(0)).add("3");
((ArrayList)al.get(0)).add("4");
((ArrayList)al.get(0)).add("5");
al.add(new ArrayList());
((ArrayList)al.get(1)).add("5");
String bz2= (String)(((ArrayList)al.get(0)).get(4));
System.out.println(al.get(0).size());
}
}

我要查询第一组的长度。 System.out.println(al.get(0).size());这一句怎么改，请指点一下小弟

System.out.println(((ArrayList)al.get(0)).size());

System.out.println(((ArrayList)al.get(0)).size());

你怎么不用泛型