升序 Collections.sort(list) 降序 Collections.reserve(list) 随机 Collections.shuffle(list)

 1 package Day28ketangzuoye;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Collections;
 5 import java.util.Comparator;
 6 import java.util.HashSet;
 7 import java.util.List;
 8 import java.util.Scanner;
 9 
10 public class DemoChars{
11 
12     public static void main(String[] args) {
13         Scanner sc=new Scanner(System.in);
14         System.out.println("请输入N个字符：");
15         String str=sc.next();
16         String[] arr=str.split(",");
17 //        System.out.println(Arrays.toString(arr)); 
18         
19         List<String> list=new ArrayList<String>();
20         for(int i=0;i<arr.length;i++){
21             list.add(arr[i]);
22         }
23         System.out.println("原序输出：  "+list); 
24         
25         Collections.sort(list);
26         System.out.println("升序输出： "+list);
27         
28         Collections.sort(list,new Comparator<String>(){
29             @Override
30             public int compare(String o1, String o2) {
31                 return o2.compareTo(o1);
32             }});
33         System.out.println("降序输出：   "+list);
34         
35         Collections.reverse(list);
36         System.out.println("反转指定列表中元素的顺序     "+list);
37         
38 //        Set set = new ArraySet(list);
39 //        HashSet<String> set=new HashSet<String>(list);
40 //        System.out.println("无序输出：  "+set); 
41 //        升序  Collections.sort(list)    降序  Collections.reserve(list)   随机  Collections.shuffle(list)        
42         
43     }
44 }