蓝桥杯 基础练习 十六进制转八进制

import java.util.*;
public class Main {
public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
 String[] st = new String[n];
for (int i = 0; i < n; i++) {
 st[i] = sc.next();
 }
 sc.close();
for (int i = 0; i < n; i++) {
 String str1 = ttos(st[i]);
int len_str1 = str1.length();
 if (len_str1 % 3 == 1) str1 = "00" + str1;
else if (len_str1 % 3 == 2) str1 = "0" + str1;
 ttoe(str1);
 System.out.println();
 }
 }

public static String ttos(String str) {
int len_str = str.length();
 StringBuilder str2 = new StringBuilder();
for (int i = 0; i < len_str; ++i) {
switch (str.charAt(i)) {
case '0':
 str2.append("0000");
break;
case '1':
 str2.append("0001");
break;
case '2':
 str2.append("0010");
break;
case '3':
 str2.append("0011");
break;
case '4':
 str2.append("0100");
break;
case '5':
 str2.append("0101");
break;
case '6':
 str2.append("0110");
break;
case '7':
 str2.append("0111");
break;
case '8':
 str2.append("1000");
break;
case '9':
 str2.append("1001");
break;
case 'A':
 str2.append("1010");
break;
case 'B':
 str2.append("1011");
break;
case 'C':
 str2.append("1100");
break;
case 'D':
 str2.append("1101");
break;
case 'E':
 str2.append("1110");
break;
case 'F':
 str2.append("1111");
break;
default:
break;
 }
 }
return str2.toString();
 }

public static void ttoe(String str2) {
int len = str2.length();
 int a;
 a = (str2.charAt(0) - '0') * 4 + (str2.charAt(1) - '0') * 2 + (str2.charAt(2) - '0');
if (a != 0) System.out.print(a);
for (int i = 3; i <= len - 3; i += 3) {
 a = (str2.charAt(i) - '0') * 4 + (str2.charAt(i + 1) - '0') * 2 + (str2.charAt(i + 2) - '0');
 System.out.print(a);
 }
 }
}

在我解决蓝桥练习的十六进制转八进制的练习中，我想要使用Integer的parseInt方法来实现将16进制的数封装到Integer对象中再输出为8进制。

        Scanner sc = new Scanner(System.in);
        int n = Integer.valueOf(sc.nextLine());
        long[] a = new long[n]; for (int i = 0; i < n; i++) { String s=sc.nextLine(); a[i] = Integer.parseInt(s, 16); } for (long b : a) { System.out.println(Long.toOctalString(b)); } sc.close();

运行小例子没问题，但是送到系统出了错。是parseInt()方法要封装的数值超出了int的范围。

例如：

　　parseInt(“2147483648”, 10) 抛出 NumberFormatException
　　parseInt(“99”, 8) 抛出 NumberFormatException
　　parseInt(“Kona”, 10) 抛出 NumberFormatException

来源：oschina

链接：https://my.oschina.net/u/4323130/blog/4238734