List<int[]>示例:https://blog.csdn.net/Awt_FuDongLai/article/details/115827705
list<list<string>>:不存在?
>>ArrayList<ArrayList<String>>格式转换成 二维数组?:https://zhidao.baidu.com/question/373288648056920644.html
String[][] array_2=(String[][]) arraylist.toArray(new String[0][0]);
>>ArrayList<String[]> array_list 我想把它转换成一个二维字符串数组:https://www.coder.work/article/3543766
public static void main( String[] args ){ String[] s1 = new String[]{ "11", "12", "13" }; String[] s2 = new String[]{ "21", "22" }; List<String[]> list = new ArrayList<String[]>(); list.add(s1); list.add(s2); String[][] ss = list.toArray(new String[0][0]); }