Java : Comparing Loans

Problem Description:
Write a program that lets the user enter the loan amount and loan period in number of years and displays the monthly and total payments for each interest rate starting from 5% to 8%, with an increment of 1/8 using the following formula:

monthlyPayment = loanAmount * monthlyInterestRate /(1-(1/(1 + monthlyInterestRate))^numberOfYears*12)

Here is a sample run:

Loan Amount: 10000
Number of Years: 5
Interest Rate	Monthly Payment	Total Payment
5%			    188.71			11322.74
5.125%		    189.28			11357.13
5.25%			189.85			11391.59
...
7.875%			202.17			12129.97
8.0%			202.76			12165.83

代码：

import java.math.BigDecimal;
import java.util.Scanner;

public class Exercise2_1 {
    public static void main(String[] args) {
        Scanner input=new Scanner(System.in);
        System.out.print("贷款金额:");
        double in=input.nextDouble();
        System.out.print("年限:");
        double y=input.nextDouble();
        System.out.println("利率        月供       总付");
        double a=5;
        double mp,ap;
        do{
            BigDecimal value = new BigDecimal(a);
            BigDecimal ans= value.stripTrailingZeros();
            mp=(in*a/100/12)/(1-(1/Math.pow(1+a/100/12,y*12)));
            ap=mp*y*12;
            System.out.print(ans+"%\t");
            System.out.printf("    %.2f    %.2f \n",mp,ap);
            a+=0.125;
        }while(a<=8);
        input.close();
    }
}