Java 设计一个贷款计算器 简易

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.border.*;

public class LoanCalculator extends JFrame {
private class ButtonListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
double interest=
Double.parseDouble(jtfAnnualInterestRate.getText());
int year=
Integer.parseInt(jtfNumberOfYears.getText());
double loanAmount=
Double.parseDouble(jtfLoanAmount.getText());

double monthlyInterest=interest/1200;
double monthlyPayment= loanAmount*monthlyInterest/(1-1/Math.pow(1+monthlyInterest,
year*12));
double totalPayment=monthlyPayment*year*12;

jtfMonthlyPayment.setText(String.format("%.2f", monthlyPayment));
jtfTotalPayment.setText(String.format("%.2f", totalPayment));
}
}

private JTextField jtfAnnualInterestRate=new JTextField();
private JTextField jtfNumberOfYears=new JTextField();
private JTextField jtfLoanAmount=new JTextField();
private JTextField jtfMonthlyPayment=new JTextField();
private JTextField jtfTotalPayment=new JTextField();

private JButton jbtComputeLoan=new JButton("Compute Payment");

public LoanCalculator(){
JPanel p1=new JPanel(new GridLayout(5,2));
p1.add(new JLabel("Annual Interest Rate"));
p1.add(jtfAnnualInterestRate);
p1.add(new JLabel("Number of Years"));
p1.add(jtfNumberOfYears);
p1.add(new JLabel("Loan Amount"));
p1.add(jtfLoanAmount);
p1.add(new JLabel("Monthly Payment"));
p1.add(jtfMonthlyPayment);
p1.add(new JLabel("Total Payment"));
p1.add(jtfTotalPayment);
p1.setBorder(new TitledBorder("Enter loan amount, interest rate,"
+ " and year"));

JPanel p2=new JPanel(new FlowLayout(FlowLayout.RIGHT));
p2.add(jbtComputeLoan);
add(p1,BorderLayout.CENTER);
add(p2,BorderLayout.SOUTH);
jbtComputeLoan.addActionListener(new ButtonListener());

}

public static void main(String[] args) {
// TODO Auto-generated method stub
LoanCalculator frame=new LoanCalculator();
frame.setTitle("LoanCalculator");
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}

}