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

 package Day28ketangzuoye;

 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Scanner;

 public class DemoChars{

     public static void main(String[] args) {
         Scanner sc=new Scanner(System.in);
         System.out.println("请输入N个字符：");
         String str=sc.next();
         String[] arr=str.split(",");
 //        System.out.println(Arrays.toString(arr)); 

         List<String> list=new ArrayList<String>();
         for(int i=0;i<arr.length;i++){
             list.add(arr[i]);
         }
         System.out.println("原序输出：  "+list); 

         Collections.sort(list);
         System.out.println("升序输出： "+list);

         Collections.sort(list,new Comparator<String>(){
             @Override
             public int compare(String o1, String o2) {
                 return o2.compareTo(o1);
             }});
         System.out.println("降序输出：   "+list);

         Collections.reverse(list);
         System.out.println("反转指定列表中元素的顺序     "+list);

 //        Set set = new ArraySet(list);
 //        HashSet<String> set=new HashSet<String>(list);
 //        System.out.println("无序输出：  "+set);
 //        升序  Collections.sort(list)    降序  Collections.reserve(list)   随机  Collections.shuffle(list)        

     }
 }