我正在尝试在NetBeans中创建的JFrame中创建一个简单的未来复合兴趣应用程序。用户将在JFrame中的每个JTextField中键入当前金额，季度费率和年数。当用户点击＆＃39;计算＆＃39;按下resultTextField应该打印结果。但是，无论输入的数字是什么，我的程序都会返回0。
我猜这段代码中缺少一些东西：
private void calculateButtonActionPerformed(java.awt.event.ActionEvent evt) {
if(evt.getSource().equals(calculateButton))
{
result = compoundMethod(int1, int2, int3);
resultTextField.setText(String.valueOf(result));
}
}
我不确定这里的问题是什么。有人可以帮我吗。非常感谢它。谢谢！
package apppackage; //Declared in netbeans
public class interestGUI extends javax.swing.JFrame {
public double int1 = 0;
public double int2 = 0;
public double int3 = 0;
public double result = 0;
/**
* Creates new form interestGUI
*/
public interestGUI() {
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() {
amountTextField = new javax.swing.JTextField();
rateTextField = new javax.swing.JTextField();
periodsTextField = new javax.swing.JTextField();
AmountLabel = new javax.swing.JLabel();
RateLabel = new javax.swing.JLabel();
PeriodsLabel = new javax.swing.JLabel();
FormulaTextField = new javax.swing.JTextField();
resultTextField = new javax.swing.JTextField();
jLabel1 = new javax.swing.JLabel();
calculateButton = new javax.swing.JButton();
jLabel2 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
amountTextField.setText("0");
amountTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
amountTextFieldActionPerformed(evt);
}
});
rateTextField.setText("0");
rateTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
rateTextFieldActionPerformed(evt);
}
});
periodsTextField.setText("0");
periodsTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
periodsTextFieldActionPerformed(evt);
}
});
AmountLabel.setText("Amount");
RateLabel.setText("Rate");
PeriodsLabel.setText("Periods");
FormulaTextField.setText("S = P ( 1 + i * t) ");
FormulaTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
FormulaTextFieldActionPerformed(evt);
}
});
resultTextField.setText("0");
resultTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
resultTextFieldActionPerformed(evt);
}
});
jLabel1.setText("Future Value Formula");
calculateButton.setText("Calculate");
calculateButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
calculateButtonActionPerformed(evt);
}
});
jLabel2.setText("Result:");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(172, 172, 172)
.addComponent(calculateButton))
.addGroup(layout.createSequentialGroup()
.addGap(94, 94, 94)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(17, 17, 17)
.addComponent(jLabel2)
.addGap(18, 18, 18)
.addComponent(resultTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 91, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(AmountLabel)
.addComponent(amountTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 49, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(50, 50, 50)
.addComponent(RateLabel)
.addGap(54, 54, 54))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(rateTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 52, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(37, 37, 37)))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(PeriodsLabel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(periodsTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)))))
.addGroup(layout.createSequentialGroup()
.addGap(154, 154, 154)
.addComponent(FormulaTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 111, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGap(143, 143, 143)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 134, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(128, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(4, 4, 4)
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(FormulaTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 34, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(AmountLabel)
.addComponent(RateLabel)
.addComponent(PeriodsLabel))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(amountTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(rateTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(periodsTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addComponent(calculateButton)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(resultTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2))
.addGap(26, 26, 26))
);
pack();
}// </editor-fold>
public double compoundMethod(double presentValue,
double interestRate, double totalInterestPeriods )
{
double compoundBalance;
totalInterestPeriods = totalInterestPeriods*4;
interestRate = ((interestRate/100) / 4); // Compute interestRate (updated)
compoundBalance = presentValue*(Math.pow(1+interestRate, totalInterestPeriods));
return compoundBalance;
}
private void amountTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
int1 = Double.parseDouble(amountTextField.getText());
}
private void rateTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
int2 = Double.parseDouble(rateTextField.getText());
}
private void periodsTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
int3 = Double.parseDouble(periodsTextField.getText());
}
private void FormulaTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void calculateButtonActionPerformed(java.awt.event.ActionEvent evt) {
if(evt.getSource().equals(calculateButton))
{
result = compoundMethod(int1, int2, int3);
resultTextField.setText(String.valueOf(result));
}
}
private void resultTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
resultTextField.setText(String.valueOf(result));
}
/**
* @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(interestGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(interestGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(interestGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(interestGUI.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 interestGUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel AmountLabel;
private javax.swing.JTextField FormulaTextField;
private javax.swing.JLabel PeriodsLabel;
private javax.swing.JLabel RateLabel;
private javax.swing.JTextField amountTextField;
private javax.swing.JButton calculateButton;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JTextField periodsTextField;
private javax.swing.JTextField rateTextField;
private javax.swing.JTextField resultTextField;
// End of variables declaration
}
答案 0 :(得分：4)
您的基本问题归结为对ActionEvent生成JTextField的方式的误解。
基本上，当用户按下 Enter 键时（通常）会生成它们。这意味着，如果您在字段具有焦点时从不按 Enter ，则值int1，int2和int3为0
相反，当用户按下 Calculate 按钮时，从字段中获取值
private void calculateButtonActionPerformed(java.awt.event.ActionEvent evt) {
if (evt.getSource().equals(calculateButton)) {
int1 = Double.parseDouble(amountTextField.getText());
int2 = Double.parseDouble(rateTextField.getText());
int3 = Double.parseDouble(periodsTextField.getText());
result = compoundMethod(int1, int2, int3);
resultTextField.setText(String.valueOf(result));
}
}
我还建议您查看使用JSpinner或JFormattedTextField哪些能够比JTextField更好地管理数值
有关详细信息，请查看How to Use Text Fields，How to Write an Action Listeners，How to Use Spinners和How to Use Formatted Text Fields