java 十进制转十六进制

java 十进制转十六进制

第一种方法：Integer.toHexString(a)
这种方法在蓝桥杯练习系统中会判错，但是测试用例输出的确实正确的。输入 15 输出 F。但是会被判错

import java.util.*;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		System.out.println(Integer.toHexString(a));
	}
}

第二种方法
这种方法不会判错

public class Base02 {
// 正十六进制转十进制
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入一个正整数：");
		int a = sc.nextInt();
		
		StringBuffer sbuffer = new StringBuffer();
		while(true) {
			switch(a%16) {
			case 0: sbuffer.append("0"); break;
			case 1: sbuffer.append("1"); break;
			case 2: sbuffer.append("2"); break;
			case 3: sbuffer.append("3"); break;
			case 4: sbuffer.append("4"); break;
			case 5: sbuffer.append("5"); break;
			case 6: sbuffer.append("6"); break;
			case 7: sbuffer.append("7"); break;
			case 8: sbuffer.append("8"); break;
			case 9: sbuffer.append("9"); break;
			case 10: sbuffer.append("A"); break;
			case 11: sbuffer.append("B"); break;
			case 12: sbuffer.append("C"); break;
			case 13: sbuffer.append("D"); break;
			case 14: sbuffer.append("E"); break;
			case 15: sbuffer.append("F"); break;
			}
			
			if(a/16==0) {
				break;
			}
			a /= 16;
		}
		System.out.format("十进制转为十六进制为：%s", sbuffer.reverse().toString());
	}
}

从别的博主看到更简洁的方法

package com.succez.task2;
import java.util.Scanner;
/**
 * 
Copyright: Copyright (c) 2018
 * 
succez
 * @author ZhangJinjin
 * @createdate 2018年5月4日
 */
public class intToHex_Alter {

    /**
     * 这次算法用了StringBuffer效率更好
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        System.out.println("请输入要转换的十进制的数：");
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();        
        System.out.println("转换的十六进制的数为："+intToHex(n));
    }

    private static String intToHex(int n) {
        //StringBuffer s = new StringBuffer();
        StringBuilder sb = new StringBuilder(8);
        String a;
        char []b = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
        while(n != 0){
            sb = sb.append(b[n%16]);
            n = n/16;            
        }
        a = sb.reverse().toString();
        return a;
    }
}