java：Arrays类

//public static String toString(数组) //将参数数组变为字符串
//public static void sort(数组)   //将数组进行升序排序

//将字符串转换为数组在进行排序
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入一串字符:");
        String s=sc.next();
        //将字符串变为数组
        char[] ch=s.toCharArray();
        //进行升序排序
        Arrays.sort(ch);
        System.out.println("排序前:");
        for (int i = 0; i < ch.length; i++) {
            System.out.print(ch[i]+"\t");
        }
        System.out.println("降序排序后:");
        for (int i = ch.length - 1; i >= 0; i--) {
            System.out.print(ch[i]+"\t");
        }

https://www.cnblogs.com/xudong-bupt/p/3168618.html