我的单选按钮出现问题。我可以同时点击这三个。它应该是当你点击一个时另一个关闭？
我正在使用网格布局。所以当我尝试group.add它不起作用。
示例：
我按钮声明了这个
JRadioButton seven = new JRadioButton("7 years at 5.35%", false);
JRadioButton fifteen = new JRadioButton("15 years at 5.5%", false);
JRadioButton thirty = new JRadioButton("30 years at 5.75%", false);
ButtonGroup group = new ButtonGroup();
grid.add(seven);
grid.add(fifteen);
grid.add(thirty);
这是我的代码：
/*Change Request #6
Write the program in Java (with a graphical user interface)
so that it will allow the user to select which way
they want to calculate a mortgage:
by input of the amount of the mortgage,
the term of the mortgage,
and the interest rate of the mortgage payment
or by input of the amount of a mortgage and
then select from a menu of mortgage loans:
- 7 year at 5.35%
- 15 year at 5.5 %
- 30 year at 5.75%
In either case, display the mortgage payment amount
and then, list the loan balance and interest paid
for each payment over the term of the loan.
Allow the user to loop back and enter a new amount
and make a new selection, or quit.
Insert comments in the program to document the program.
*/
import java.text.NumberFormat;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class WK4 extends JFrame implements ActionListener
{
int loanTerms[] = { 7, 15, 30 };
double annualRates[] = { 5.35, 5.5, 5.75 };
// Labels
JLabel AmountLabel = new JLabel(" Loan Amount $ ");
JLabel PaymentLabel = new JLabel(" Monthly Payment ");
JLabel InterestLabel = new JLabel(" Interest Rate % ");
JLabel TermLabel = new JLabel(" Years of Loan ");
// Text Fields
JTextField mortgageAmount = new JTextField(6);
JTextField Payment = new JTextField(6);
JTextField InterestRate = new JTextField(3);
JTextField Term = new JTextField(3);
// Radio Buttons
ButtonGroup radioGroup = new ButtonGroup();
JRadioButton seven = new JRadioButton("7 years at 5.35%");
JRadioButton fifteen = new JRadioButton("15 years at 5.5%");
JRadioButton thirty = new JRadioButton("30 years at 5.75%");
// Buttons
JButton exitButton = new JButton("Exit");
JButton resetButton = new JButton("Reset");
JButton calculateButton = new JButton("Calculate ");
// Text Area
JTextArea LoanPayments = new JTextArea(20, 50);
JTextArea GraphArea = new JTextArea(20, 50);
JScrollPane scroll = new JScrollPane(LoanPayments);
public WK4(){
super("Mortgage Calculator");
//Window
setSize(700, 400);
setLocation(200, 150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel pane = new JPanel(new GridLayout(2, 2));
Container grid = getContentPane();
grid.setLayout(new GridLayout(4, 10, 0, 12)); //rows, cols, hgap, vgap
pane.add(grid);
pane.add(scroll);
grid.add(AmountLabel);
grid.add(mortgageAmount);
grid.add(InterestLabel);
grid.add(InterestRate);
grid.add(TermLabel);
grid.add(Term);
grid.add(PaymentLabel);
grid.add(Payment);
grid.add(Box.createHorizontalStrut(15));
ButtonGroup group = new ButtonGroup();
grid.add(seven);
grid.add(fifteen);
grid.add(thirty);
grid.add(calculateButton);
grid.add(resetButton);
grid.add(exitButton);
Payment.setEditable(false);
setContentPane(pane);
setContentPane(pane);
setVisible(true);
// Action Listeners
mortgageAmount.addActionListener(this);
InterestRate.addActionListener(this);
Term.addActionListener(this);
Payment.addActionListener(this);
seven.addActionListener(this);
fifteen.addActionListener(this);
thirty.addActionListener(this);
calculateButton.addActionListener(this);
exitButton.addActionListener(this);
resetButton.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
Object command = e.getSource();
if (command == exitButton) {
System.exit(0);
}
else if (command == seven) {
calcLoan(loanTerms[0], annualRates[0]);
}
else if (command == fifteen) {
calcLoan(loanTerms[1], annualRates[1]);
}
else if (command == thirty) {
calcLoan(loanTerms[2], annualRates[2]);
}
else if (command == calculateButton) {
double years = 0;
double rates = 0;
try {
years = Double.parseDouble(Term.getText());
rates = Double.parseDouble(InterestRate.getText());
}
catch (Exception ex) {
LoanPayments.setText("Invalid Amount");
return;
}
calcLoan(years, rates);
}
else if (command == resetButton) {
mortgageAmount.setText("");
Payment.setText("");
InterestRate.setText("");
Term.setText("");
LoanPayments.setText("");
}
}
private void calcLoan(double years, double rates) {
Term.setText(String.valueOf(years));
InterestRate.setText(String.valueOf(rates));
double amount = 0;
try {
amount = Double.parseDouble(mortgageAmount.getText());
}
catch (Exception ex) {
LoanPayments.setText("Invalid Amount");
return;
}
double interestRate = rates;
double intRate = (interestRate / 100) / 12;
int months = (int) years * 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;
NumberFormat CurrencyFormatter = NumberFormat.getCurrencyInstance();
Payment.setText(CurrencyFormatter.format(payment));
LoanPayments.setText(" Month\tPrincipal\tInterest\tEnding Balance\n");
int currentMonth = 0;
while (currentMonth < months) {
MonthlyInterest = (remainingPrincipal * intRate);
MonthlyAmt = (payment - MonthlyInterest);
remainingPrincipal = (remainingPrincipal - MonthlyAmt);
LoanPayments.append((++currentMonth) + "\t"
+ CurrencyFormatter.format(MonthlyAmt) + "\t"
+ CurrencyFormatter.format(MonthlyInterest) + "\t"
+ CurrencyFormatter.format(remainingPrincipal) + "\n");
GraphArea.append("" + remainingPrincipal);
}
}
public static void main(String[] args) {
new WK4();
}
}
答案 0 :(得分：5)
您正在将单选按钮添加到网格中，但您还需要将它们添加到您定义的按钮组中。
也许这个：
ButtonGroup group = new ButtonGroup();
grid.add(seven);
grid.add(fifteen);
grid.add(thirty);
应该是这样的：??? （复制/粘贴bug？）
ButtonGroup group = new ButtonGroup();
group.add(seven);
group.add(fifteen);
group.add(thirty);
或者你可能需要同时做这两件事。单选按钮必须属于容器以及要显示的按钮组并且行为正常。