【发布时间】：2014-05-15 22:17:16
【问题描述】：
我正在做一个项目，我必须将分数转换为最低项。我在使用来自 JTextField 的 .getText 时遇到错误。我打印了他们的输入，输入作为属性而不是字符串被接收。我遇到了这段代码的问题：
double userDenominator = Double.parseDouble(userDenominatorInput.getText());
这给变量一个值
javax.swing.JTextField[,12,93,166x36,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@c112a58,flags=296,maximumSize=,minimumSize=,preferredSize=,caretColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],disabledTextColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],selectionColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],columns=0,columnWidth=0,command=,horizontalAlignment=LEADING]
我想知道我使用 GUI 表单或释放键的侦听器是否会导致任何问题。
这里是分为两个类的完整代码：
package reducefraction;
public class ReduceFraction {
public static void main(String[] args) {
NewJFrame form = new NewJFrame();
form.setVisible(true);
form.setLocationRelativeTo(null);
}
}
这是第二课
package reducefraction;
public class NewJFrame extends javax.swing.JFrame {
/**
* Creates new form NewJFrame
*/
public NewJFrame() {
initComponents();
userDenominatorInput.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyReleased(java.awt.event.KeyEvent evt) {
userDenominatorInputKeyReleased(evt);
}
});
userNumeratorInput.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyReleased(java.awt.event.KeyEvent evt) {
userNumeratorInputKeyReleased(evt);
}
});
}
/**
* 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() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jSeparator1 = new javax.swing.JSeparator();
userDenominatorInput = new javax.swing.JTextField();
jSeparator2 = new javax.swing.JSeparator();
numeratorOutput = new javax.swing.JTextField();
denominatorOutput = new javax.swing.JTextField();
jLabel3 = new javax.swing.JLabel();
userNumeratorInput = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setText("Reduce Fractions");
jLabel2.setText("This program will reduce a fraction to its lowest terms");
userDenominatorInput.setFont(new java.awt.Font("Gabriola", 1, 24)); // NOI18N
userDenominatorInput.setForeground(new java.awt.Color(255, 102, 51));
numeratorOutput.setEditable(false);
numeratorOutput.setColumns(10);
numeratorOutput.setFont(new java.awt.Font("Gabriola", 1, 24)); // NOI18N
numeratorOutput.setForeground(new java.awt.Color(255, 102, 51));
denominatorOutput.setEditable(false);
denominatorOutput.setColumns(10);
denominatorOutput.setFont(new java.awt.Font("Gabriola", 1, 24)); // NOI18N
denominatorOutput.setForeground(new java.awt.Color(255, 102, 51));
jLabel3.setFont(new java.awt.Font("Tempus Sans ITC", 1, 36)); // NOI18N
jLabel3.setText("=");
userNumeratorInput.setFont(new java.awt.Font("Gabriola", 1, 24)); // NOI18N
userNumeratorInput.setForeground(new java.awt.Color(255, 102, 51));
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()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(155, 155, 155)
.addComponent(jLabel1))
.addGroup(layout.createSequentialGroup()
.addGap(75, 75, 75)
.addComponent(jLabel2)))
.addGap(0, 82, Short.MAX_VALUE))
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jSeparator1)
.addComponent(userDenominatorInput, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 166, Short.MAX_VALUE)
.addComponent(userNumeratorInput))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel3)
.addGap(29, 29, 29)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jSeparator2)
.addComponent(denominatorOutput, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(numeratorOutput, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addGap(18, 18, 18)
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 31, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addGroup(layout.createSequentialGroup()
.addComponent(userNumeratorInput, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 2, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(userDenominatorInput, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jSeparator2, javax.swing.GroupLayout.PREFERRED_SIZE, 2, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 14, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(denominatorOutput, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(numeratorOutput, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(50, 50, 50)))
.addGap(22, 22, 22))
);
pack();
}// </editor-fold>
**public void userDenominatorInputKeyReleased(java.awt.event.KeyEvent evt) {
double userDenominator = Double.parseDouble(userDenominatorInput.getText());
double userNumerator = Double.parseDouble(userNumeratorInput.getText());
calculate(userNumerator, userDenominator);
}
public void userNumeratorInputKeyReleased(java.awt.event.KeyEvent evt) {
double userDenominator = Double.parseDouble(userDenominatorInput.getText());
double userNumerator = Double.parseDouble(userNumeratorInput.getText());
calculate(userNumerator, userDenominator);
}
public void calculate(double userNumerator, double userDenominator) {
System.out.println(userNumeratorInput);
double a = userDenominator;
double b = userNumerator % userDenominator;
double c;
do {
c = a % b;
a = b;
b = c;
} while (a != 0);
int greatestCommonDenominator = (int) c;
double numeratorAnswer = userNumerator / greatestCommonDenominator;
double denominatorAnswer = userDenominator / greatestCommonDenominator;
numeratorOutput.setText(Double.toString(numeratorAnswer));
denominatorOutput.setText(Double.toString(denominatorAnswer));
}**
/**
* @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(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.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 NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JTextField denominatorOutput;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JSeparator jSeparator1;
private javax.swing.JSeparator jSeparator2;
private javax.swing.JTextField numeratorOutput;
public javax.swing.JTextField userDenominatorInput;
private javax.swing.JTextField userNumeratorInput;
// End of variables declaration
}
【问题讨论】：
-
不要在文本字段上使用
KeyListeners，如果您想实时更新或依赖ActionListener支持字段，请使用DocumentListener
标签： java swing textfield gettext