Java 数字转换成罗马字

青旅半醒 2022-05-22 11:08 301阅读 0赞

***Converter .java***

package main;
    
    /**
     * @author cm_wang
     *
     * 转换工具类
     */
    public class Converter {
    	
    	public static final String[][] str = {  
                {"","I","II","III","IV","V","VI","VII","VIII","IX"},  // 个位数举例
                {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"},  // 十位数举例
                {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"},  // 百位数举例
                {"","M","MM","MMM"}  // 千位数举例
        };  
    	
    	
    	/**
    	 * @param nubmer
    	 * @return
    	 * 
    	 * 思路是：千位先除以1000然后模10，百位先除以100然后模10，十位先除以10然后模10，个位直接模10.
    	 */
    	public static String convert(String strNubmer) {
    		StringBuilder strBuilder = new StringBuilder();
    		int number = Integer.parseInt(strNubmer);
    		
    		strBuilder.append(str[3][number/1000%10]);  
    		strBuilder.append(str[2][number/100%10]);  
    		strBuilder.append(str[1][number/10%10]);  
    		strBuilder.append(str[0][number%10]); 
    		return strBuilder.toString();
    	} 
    }

***InputHelper.java***

package main;
    
    import java.util.regex.Pattern;
    import java.util.regex.Matcher;
    
    /**
     * @author cm_wang
     *
     * 过滤工具类
     */
    public class InputHelper {
    
    	/**
    	 * @param str
    	 * @return 过滤后的数字
    	 * 
    	 * 过滤掉除了数字以外的所有非法字符。
    	 */
    	public static String getNumber(String str) {
    		
            String regEx = "[^0-9]";
            Pattern p = Pattern.compile(regEx);
            Matcher m = p.matcher(str);
            return m.replaceAll("").trim();
    	}
    }

***Roman.java***

package main;
    import static main.Converter.*;
    import static main.InputHelper.*;
    
    import java.util.Scanner;
    
    /**
     * @author cm_wang
     *
     * main class.
     */
    public class Roman {
    
    	@SuppressWarnings("resource")
    	public static void main(String[] args) throws Exception {
    		
    		while(true){
    			System.out.println();  
    	        System.out.print("请输入0~3999的阿拉伯数字：");  
    			Scanner sc = new Scanner(System.in);
                String str = getNumber(sc.nextLine());
                    	
                try {
                	System.out.println("转换后的罗马数字为：" + convert(str));  
                }catch(Exception e) {
                    System.out.println("非法字符，请输入数字！");  
                }
    		}
    	}
    
    }