好的，我在这里有一个问题，我无法安静地弄明白。我有一个文件在每行上有变量：5.35,5.5,5.75在一个名为apr.txt的文件中。我正在读取文件，需要将文件填充到JComboBox中。到目前为止，我已经将文件读取正常，但无法确定如何将其填充到JComboBox中。这一定很容易。有人能指点我正确的方向吗？
提前感谢您的帮助。
import java.awt.*;
import java.text.NumberFormat;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.StringTokenizer;
import javax.swing.*;
import javax.swing.JComboBox;
public class MortgageCalculatorGUI9 extends JFrame implements ActionListener
{
// Declarations
//double [] Interest = {5.35, 5.5, 5.75};
int [] Length = {7, 15, 30};
double [] file_data = new double[3];
JLabel mortgagelabel = new JLabel( "Principal Amount:$ " );
JLabel paymentLabel = new JLabel( "Monthly Payment: " );
JLabel intRateLabel = new JLabel( "Interest Rate %: " );
JLabel termLabel = new JLabel( "Length of Loan of Loan in Years: " );
JTextField mortgagePrincipal = new JTextField(7);
JTextField Payment = new JTextField(7);
//JTextField intRateText = new JTextField(3);
JComboBox intRateBox = new JComboBox();
JTextField termText = new JTextField(3);
JButton b7_535 = new JButton( "7 years at 5.35%" );
JButton b15_55 = new JButton( "15 years at 5.50%" );
JButton b30_575 = new JButton( "30 years at 5.75%");
JButton exitButton = new JButton( "Exit" );
JButton clearButton = new JButton( "Clear All" );
JButton calculateButton = new JButton( "Calculate Loan" );
JTextArea LoanPayments = new JTextArea(20,50);
JScrollPane scroll = new JScrollPane(LoanPayments);
public MortgageCalculatorGUI9()
{
//GUI setup
super("Mortgage Calculator 1.0.5");
setSize(800, 400);
setLocation(500, 200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel pane = new JPanel(new GridLayout(3,1)); Container grid = getContentPane();
grid.setLayout(new GridLayout(4,0,4,4)); pane.add(grid);
pane.add(scroll);
grid.add(mortgagelabel);
grid.add(mortgagePrincipal);
grid.add(intRateLabel);
//grid.add(intRateText);
grid.add (intRateBox);
grid.add(termLabel);
grid.add(termText);
grid.add(paymentLabel);
grid.add(Payment);
grid.add(b7_535);
grid.add(b15_55);
grid.add(b30_575);
grid.add(calculateButton);
grid.add(clearButton);
grid.add(exitButton);
Payment.setEditable(false);
setContentPane(pane);
setContentPane(pane);
setVisible(true);
//add GUI functionality
calculateButton.addActionListener (this);
exitButton.addActionListener(this);
clearButton.addActionListener(this);
b7_535.addActionListener(this);
b15_55.addActionListener(this);
b30_575.addActionListener(this);
mortgagePrincipal.addActionListener(this);
//intRateText.addActionListener(this);
intRateBox.addActionListener (this);
termText.addActionListener(this);
Payment.addActionListener(this);
}
public void actionPerformed(ActionEvent e)
{
Object command = e.getSource();
if (command == exitButton)
{
System.exit(0);
}
else if (command == b7_535)
{
calcLoan(Length[0], file_data[0]);
}
else if (command == b15_55)
{
calcLoan(Length[1], file_data[1]);
}
else if (command == b30_575)
{
calcLoan(Length[2], file_data[2]);
}
else if (command == calculateButton )
{
double terms = 0;
double rates = 0;
try
{
terms = Double.parseDouble(termText.getText());
//rates = Double.parseDouble(intRateText.getText());
read_File ();
}
catch (Exception ex)
{
LoanPayments.setText("Invalid term or rate Amount");
return;
}
calcLoan(terms, rates);
}
else if (command == clearButton)
{
mortgagePrincipal.setText("");
Payment.setText("");
//intRateText.setText("");
termText.setText("");
LoanPayments.setText("");
}
}
//Input File
public void read_File()
{
File inFile = new File("apr.txt");
try
{
BufferedReader istream = new BufferedReader(new FileReader(inFile));
for(int x=0;x<6;x++)
{
file_data[x]=Double.parseDouble (istream.readLine());
}
}
catch (Exception ex)
{
LoanPayments.setText ("Could Not Read From File.");
return;
}
}
//this is what needs to be done
private void calcLoan(double terms, double rates)
{
termText.setText(String.valueOf(terms) );
//intRateText.setText(String.valueOf(rates));
double amount = 0;
try
{
amount = Double.parseDouble(mortgagePrincipal.getText());
}
catch (Exception ex)
{
LoanPayments.setText("Invalid mortgage Amount");
return;
}
double interestRate = rates;
// Calculations
double intRate = (interestRate / 100) / 12;
int Months = (int)terms * 12;
double rate = (intRate / 12);
double payment = amount * intRate / (1 - (Math.pow(1/(1 + intRate), Months)));
double remainingPrincipal = amount;
double MonthlyInterest = 0;
double MonthlyAmt = 0;
double[] balanceArray = new double[Months];
double[] interestArray = new double[Months];
double[] monthArray = new double[Months];
NumberFormat Money = NumberFormat.getCurrencyInstance();
Payment.setText(Money.format(payment));
LoanPayments.setText("Month\tPrincipal\tInterest\tEnding Balance\n");
int currentMonth = 0;
while(currentMonth < Months)
{
//create loop calculations
MonthlyInterest = (remainingPrincipal * intRate);
MonthlyAmt = (payment - MonthlyInterest);
remainingPrincipal = (remainingPrincipal - MonthlyAmt);
LoanPayments.append((++currentMonth) + "\t" + Money.format(MonthlyAmt) + "\t" + Money.format(MonthlyInterest) + "\t" + Money.format(remainingPrincipal) + "\n");
balanceArray[currentMonth] = MonthlyAmt;
interestArray[currentMonth] = MonthlyInterest;
monthArray[currentMonth] = currentMonth;
}
}
public static void main(String[] args)
{
MortgageCalculatorGUI9 frame= new MortgageCalculatorGUI9();
}
}
答案 0 :(得分：1)
您是否看过JComboBox API的合适方法？如果你从那里开始，你可能会比在StackOverflow中询问更快得到正确的答案（暗示它以“add ...并以...... Item结尾”开头）;）