很抱歉代码很多，但我觉得有必要。我想知道我的代码有什么问题。在GUI界面方面，我是初学者。当我运行我的程序时，窗口弹出，当我陈词滥调时计算整个程序冻结，我甚至无法弄清楚它有什么问题。你们看到我可能做错了吗
package my.mortgagecalculation3;
import java.text.NumberFormat;
import javax.swing.JOptionPane;
import javax.swing.JFrame;
/**
*
* @author Akira
*/
public class MortgageCalculation3UI extends javax.swing.JFrame {
/**
* Creates new form MortgageCalculation3UI
*/
public MortgageCalculation3UI() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
javax.swing.JLabel lblMortgageCalculator = new javax.swing.JLabel();
lblLoanAmount = new javax.swing.JLabel();
lblInterestRate = new javax.swing.JLabel();
lblNumberYears = new javax.swing.JLabel();
lblMonthly = new javax.swing.JLabel();
txtLoanAmount = new javax.swing.JTextField();
txtInterestRate = new javax.swing.JTextField();
txtNumberYears = new javax.swing.JTextField();
txtMonthlyPayment = new javax.swing.JTextField();
btnCalculate = new javax.swing.JButton();
btnReset = new javax.swing.JButton();
btnExit = new javax.swing.JButton();
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 109, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 114, Short.MAX_VALUE)
);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
lblMortgageCalculator.setFont(new java.awt.Font("Times New Roman", 1, 18)); // NOI18N
lblMortgageCalculator.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblMortgageCalculator.setText("Mortgage Calculator");
lblLoanAmount.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
lblLoanAmount.setHorizontalAlignment(javax.swing.SwingConstants.LEFT);
lblLoanAmount.setLabelFor(lblLoanAmount);
lblLoanAmount.setText("Loan Amount :");
lblInterestRate.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
lblInterestRate.setText("Interest Rate :");
lblInterestRate.setToolTipText("");
lblInterestRate.setName("lblInterestRate"); // NOI18N
lblNumberYears.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
lblNumberYears.setText("Years to pay :");
lblNumberYears.setToolTipText("");
lblMonthly.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
lblMonthly.setText("Monthly Payment :");
txtLoanAmount.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
txtLoanAmount.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
txtLoanAmountActionPerformed(evt);
}
});
txtInterestRate.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
txtNumberYears.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
txtMonthlyPayment.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N
btnCalculate.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
btnCalculate.setText("Calculate");
btnCalculate.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnCalculateActionPerformed(evt);
}
});
btnReset.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
btnReset.setText("Reset");
btnReset.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnResetActionPerformed(evt);
}
});
btnExit.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N
btnExit.setText("Exit");
btnExit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnExitActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblMortgageCalculator, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addGap(23, 23, 23)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addComponent(lblMonthly)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(txtMonthlyPayment))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(lblInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, 84, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(lblLoanAmount)
.addComponent(lblNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, 84, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(34, 34, 34)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(txtLoanAmount)
.addComponent(txtInterestRate)
.addComponent(txtNumberYears, javax.swing.GroupLayout.DEFAULT_SIZE, 154, Short.MAX_VALUE))))
.addGroup(layout.createSequentialGroup()
.addComponent(btnCalculate, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(btnReset, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(btnExit, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(0, 28, Short.MAX_VALUE)))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(19, 19, 19)
.addComponent(lblMortgageCalculator, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lblLoanAmount, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(txtLoanAmount, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lblInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(txtInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lblNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(txtNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(45, 45, 45)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(lblMonthly, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(txtMonthlyPayment, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 50, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(btnCalculate, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 38, Short.MAX_VALUE)
.addComponent(btnExit, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(btnReset, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGap(27, 27, 27))
);
pack();
}// </editor-fold>
private void btnExitActionPerformed(java.awt.event.ActionEvent evt) {
System.exit(0);
}
private void btnResetActionPerformed(java.awt.event.ActionEvent evt) {
txtLoanAmount.setText("");
txtInterestRate.setText("");
txtNumberYears.setText("");
}
private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {
JFrame frame = new JFrame();
double loanAmount = 0;
double interestRate = 0;
double numberYears = 0;
double months;
double monthlyPayment;
double numerator;
double denominator;
double formula;
String runAgain = "y";
while (runAgain.equals("y")) {
try {
loanAmount = 0;
interestRate = 0;
numberYears = 0;
loanAmount = Double.parseDouble(txtLoanAmount.getText());
interestRate = Double.parseDouble(txtInterestRate.getText());
numberYears = Double.parseDouble(txtNumberYears.getText());
//if the user enters a negative number print out a error message, if not, continue calculations
if ((loanAmount <= 0) || (interestRate <= 0) || (numberYears <= 0)) {
JOptionPane.showMessageDialog(frame,
"You must enter positive numerical data!",
"Invalid Data!",
JOptionPane.ERROR_MESSAGE);
} else {
//convert the interest rate
interestRate = interestRate / 100 / 12;
//the number of years must be converted to months
months = numberYears * 12;
//numerator of the monthly payment formula
numerator = (Math.pow(1 + interestRate, months));
//denominator of the monthly payment formula
denominator = ((numerator)-1);
//the formula equals the numerator divided by the denominator
formula = ( numerator / denominator );
//monthly payment calculation
monthlyPayment = (interestRate * loanAmount * formula);
//sytem output
NumberFormat defaultFormat = NumberFormat.getCurrencyInstance();
defaultFormat.format(monthlyPayment);
txtMonthlyPayment.setText(Double.toString(monthlyPayment));
}
} catch (NumberFormatException e) {
JOptionPane.showMessageDialog(frame,
"You must enter positive numerical data!",
"Invalid Data!",
JOptionPane.ERROR_MESSAGE);
}
}
}
private void txtLoanAmountActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MortgageCalculation3UI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btnCalculate;
private javax.swing.JButton btnExit;
private javax.swing.JButton btnReset;
private javax.swing.JPanel jPanel1;
private javax.swing.JLabel lblInterestRate;
private javax.swing.JLabel lblLoanAmount;
private javax.swing.JLabel lblMonthly;
private javax.swing.JLabel lblNumberYears;
private javax.swing.JTextField txtInterestRate;
private javax.swing.JTextField txtLoanAmount;
private javax.swing.JTextField txtMonthlyPayment;
private javax.swing.JTextField txtNumberYears;
// End of variables declaration
}
答案 0 :(得分：1)
问题在于您的btnCalculateActionPerformed(java.awt.event.ActionEvent evt)方法：
String runAgain = "y";
while (runAgain.equals("y")) {
// do stuff here
}
while循环条件始终评估为true。计算完成后，您必须将变量更改为其他变量。对于这种情况，我认为最好使用boolean代替String。我想知道为什么需要这样做：一旦完成计算，再次运行就没有意义了。将结果呈现给用户。如果他想再次运行计算，他会再次按下按钮。
请注意，您正在UI线程中运行计算，这是一件坏事：如果它们花费的时间太长，您的应用程序会冻结。也许你可以take a look at Swing Workers。