java中的进制转换

import java.util.Scanner;

public class JinZhi {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int n,m,a = 0;
        int t;
        int num[];
        num = new int[1000];
        int i = 0;
        int j;
        int w,e;//表示几进制
        int choice;
      Scanner input = new Scanner(System.in);
      while(true)
      {
     
      System.out.print("请输入一个数:");
      n = input.nextInt();
      System.out.print("请输入这个数的进制:");
      w = input.nextInt();
      System.out.print("请输入要转为几进制:");
      e = input.nextInt();
      int c = 0;
      while(n != 0)
      {
          t = n % 10;
          a += t *(Math.pow(w, c));
          c ++;
          n = n / 10;
                  
      }
      m = a;
      while(a != 0)
      {
          t = a % e;
          num[i] = t;
          a = a / e;
          i ++;
      }
      System.out.print(m + "的" + e + "进制:");
      for(j = i - 1;j >= 0 &&num[j] != -1;j --)
      {
          System.out.print(num[j] + "\t");
          num[j] = -1;
          
      }
      System.out.println("\n");
      System.out.println("1,继续操作");
      System.out.println("2,退出系统");
      System.out.println("请输入你的选择:");
      choice = input.nextInt();
      if(choice == 2)
      {
          System.out.println("欢迎下次使用");
          break;
      }
      }
    }

}