java(StringBuilder)练习

需求:键盘录入一个九位数以下的数字将该数字各数字变为罗马数字。

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import java.util.Scanner; public class Boke {     public static void main(String[] args){         Scanner Sc= new Scanner(System.in);         String x;         while(true){             System.out.println("请输一个小于九位数的数字:");              x = Sc.next();             //判断             boolean agls = Ayue(x);             if(agls){                 break;             }else{                 System.out.println("当前的字符串不符合规则，请重新输入");                 continue;             }         }         StringBuilder sb = new StringBuilder();         for(int i =0;i<x.length();i++){             char c = x.charAt(i); //            System.out.println(c);             int y =c-48;             String s= Luoma(y);             sb.append(s+" ");         }         System.out.println(sb);     }       public static String Luoma(int y){         String arr[] = {" ","I","II","III","IV","V","VI","VII","VIII","IX"};         return arr[y];     }     public static boolean Ayue(String x){         if(x.length()>9){             return false;         }         for (int i = 0; i < x.length(); i++) {             char c = x.charAt(i);             if(c<'0'||c>'9'){                 return false;             }         }         return true;     } }