初学Java 使用输入对话框

import javax.swing.JOptionPane;
public class ComputeLoanUsingInputDialog {
  public static void main(String[] args) {
      String annualInterestRateString = JOptionPane.showInputDialog(
              "Enter yearly interest rate, for example 8.25:");
      
      double annualInterestRate =
              Double.parseDouble(annualInterestRateString);
      double monthlyInteresRate = annualInterestRate / 1200;
      String numberOfYearsString = JOptionPane.showInputDialog(
              "Enter number of years as an integer, 
for example 5:");
      
      int numberOfYears = Integer.parseInt(numberOfYearsString);
      String loanString = JOptionPane.showInputDialog(
              "Enter loan amount, for example 120000.95:");
      
      double loanAmount = Double.parseDouble(loanString);
      
      double monthlyPayment = loanAmount * monthlyInteresRate / (1
              - 1 / Math.pow(1 + monthlyInteresRate, numberOfYears * 12));
      double totalPayment = monthlyPayment * numberOfYears * 12;
      
      monthlyPayment = (int)(monthlyPayment * 100) / 100.0;
      totalPayment = (int)(totalPayment * 100) / 100.0;
      
      String output = "the monthly payment is " + monthlyPayment + 
              "
the total payment is " + totalPayment;
      JOptionPane.showMessageDialog(null, output);
      
  }
}