Integer 类型
        ArrayList<Integer> Mlist = new ArrayList<Integer>();
     
        Scanner scM = new Scanner(new File("D://m.txt"));
　　　　　
　　　　　while (scM.hasNextInt()) {
            int i = scM.nextInt();
              Mlist.add(i);
            }
　　　

/*将list转为数组*/
       Integer[] Marray = new Integer[Mlist.size()];
       Marray = (Integer[])Mlist.toArray(Marray);

String 类型
ArrayList<String> Nlist = new ArrayList<String>();

Scanner scN = new Scanner(new File("D://n.txt"));

 while (scN.hasNextLine()) {
	          String i = scN.nextLine();
	          Nlist.add(i);
	        }

/*将list转为数组*/
      String[] Narray = new String[Nlist.size()];
       Narray = (String[])Nlist.toArray(Narray);

/*数组转List*/

String[] userid = {"aa","bb","cc"};
List list = new ArrayList(Arrays.asList(userid));