1 import java.util.ArrayList; 2  3 public class Main { 4      5     public static void main(String[] args) { 6         ArrayList<Integer> list = new ArrayList<>(); 7         list.add(1); 8         list.add(2); 9         list.add(3);10         list.add(4);11         12         for(int n:list){13             n = 4;//此种做法不会改变list的元素14             //System.out.println(n);15         }16         /* 增强型for循环*/17         for (int m:list) {18             System.out.print(m + " ");19         }20         System.out.println();21         22         for(int i = 0; i < list.size();i++){23             //list.add(i);24             list.remove(i); //在for循环中，list的大小是不好的做法。25         }26         27         for (int m:list) {28             System.out.print(m+" ");29         }30     }31 }