我对Java很陌生，特别是在构建JFrame时。我一直在收到上述错误，问题似乎来自Generated Code。 请协助我清除错误并了解导致错误的原因。
package calculator;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CalcForm {
/**
* Creates new form CalcForm
*/
public CalcForm() {
initComponents();
}
//The Auto-Generated Code begins here
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
input1 = new javax.swing.JTextField();
jLabel2 = new javax.swing.JLabel();
input2 = new javax.swing.JTextField();
btnAdd = new javax.swing.JButton();
btnLess = new javax.swing.JButton();
btnEquals = new javax.swing.JButton();
jLabel3 = new javax.swing.JLabel();
disp = new javax.swing.JTextField();
//The two lines below are highlighted in RED
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Simple Calcucator");
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
jLabel1.setText("First Input:");
input1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
input1ActionPerformed(evt);
}
});
jLabel2.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
jLabel2.setText("Second Input:");
input2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
input2ActionPerformed(evt);
}
});
btnAdd.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
btnAdd.setText("+");
btnAdd.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnAddActionPerformed(evt);
}
});
btnLess.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
btnLess.setText("-");
btnLess.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnLessActionPerformed(evt);
}
});
btnEquals.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
btnEquals.setText("=");
btnEquals.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnEqualsActionPerformed(evt);
}
});
jLabel3.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
jLabel3.setText("Your Answer is:");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(79, 79, 79)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(btnEquals, javax.swing.GroupLayout.PREFERRED_SIZE, 181, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, 123, Short.MAX_VALUE))
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(61, 61, 61)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(input1)
.addComponent(btnAdd, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGap(116, 116, 116)
.addComponent(btnLess, javax.swing.GroupLayout.PREFERRED_SIZE, 65, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(input2)
.addComponent(disp))))
.addContainerGap(94, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(34, 34, 34)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(input1, javax.swing.GroupLayout.PREFERRED_SIZE, 47, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(42, 42, 42)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnAdd, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnLess, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(31, 31, 31)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(input2, javax.swing.GroupLayout.PREFERRED_SIZE, 44, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(btnEquals, javax.swing.GroupLayout.PREFERRED_SIZE, 64, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(25, 25, 25)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 48, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(disp, javax.swing.GroupLayout.PREFERRED_SIZE, 48, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(29, Short.MAX_VALUE))
);
//This also has a Red underline
pack();
}// </editor-fold>
private void input1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void input2ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void btnAddActionPerformed(java.awt.event.ActionEvent evt) {
btnAdd.setActionCommand("+");
}
private void btnLessActionPerformed(java.awt.event.ActionEvent evt) {
btnLess.setActionCommand("-");
}
private void btnEqualsActionPerformed(java.awt.event.ActionEvent evt) {
btnEquals.setActionCommand("=");
String less = btnLess.getActionCommand();
String more = btnAdd.getActionCommand();
double t = 0;
String x = input2.getText();
//parseDouble is a method used to read the given object as a double value
double y = Double.parseDouble(x);
String a = input1.getText();
double b = Double.parseDouble(a);
if (less.equals(evt)) {
t = b - y;
disp.setText(String.valueOf(t));
} else {
t = b + y;
disp.setText(String.valueOf(t));
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/*
* Create and display the form
*/
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new CalcForm();
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btnAdd;
private javax.swing.JButton btnEquals;
private javax.swing.JButton btnLess;
private javax.swing.JTextField disp;
private javax.swing.JTextField input1;
private javax.swing.JTextField input2;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
// End of variables declaration
}
显示的错误是：
Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: Uncompilable source code - Erroneous sym type: setDefaultCloseOperation
at calculator.CalcForm.initComponents(CalcForm.java:43)
at calculator.CalcForm.<init>(CalcForm.java:21)
at calculator.CalcForm$6.run(CalcForm.java:232)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
非常感谢帮助。
答案 0 :(得分：1)
如果Eclipse的 Problems 视图中仍然存在编译错误，请不要尝试运行您的应用。
您的类不会扩展JFrame，因此它没有任何setDefaultCloseOperation()方法。它也没有任何setTitle()，add() pack()等方法。您错过了班级声明中的extends JFrame部分。