我正在进行学校作业的测验，我正在尝试使用JFrame创建GUI。我有一个想法让所有按钮都不可见，只有在点击开始按钮后才出现。但是当我尝试在main方法中使用.setVisible（false）命令时，它会给我一个nullpointerexception。我不确定什么是错的，我希望有人可以给我一些指示。这是我的代码：
import javax.swing.JOptionPane;
public class QuizGUI extends javax.swing.JFrame {
/**
* Creates new form QuizGUI
*/
public QuizGUI() {
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() {
jButton4 = new javax.swing.JButton();
jPanel1 = new javax.swing.JPanel();
Q1 = new javax.swing.JButton();
jPanel2 = new javax.swing.JPanel();
Q2 = new javax.swing.JButton();
jPanel3 = new javax.swing.JPanel();
Q3 = new javax.swing.JButton();
jPanel4 = new javax.swing.JPanel();
Q4 = new javax.swing.JButton();
jPanel5 = new javax.swing.JPanel();
Q5 = new javax.swing.JButton();
jPanel7 = new javax.swing.JPanel();
Bonus = new javax.swing.JButton();
Exit = new javax.swing.JButton();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jPanel6 = new javax.swing.JPanel();
Start = new javax.swing.JButton();
EndQuiz = new javax.swing.JButton();
Timer = new javax.swing.JLabel();
jButton4.setText("jButton4");
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
Q1.setText("Question 1");
Q1.addChangeListener(new javax.swing.event.ChangeListener() {
public void stateChanged(javax.swing.event.ChangeEvent evt) {
Q1StateChanged(evt);
}
});
Q1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
Q1ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addGap(33, 33, 33)
.addComponent(Q1, javax.swing.GroupLayout.DEFAULT_SIZE, 145, Short.MAX_VALUE)
.addContainerGap())
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(Q1, javax.swing.GroupLayout.PREFERRED_SIZE, 47, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(11, 11, 11))
);
Q1.getAccessibleContext().setAccessibleName("Question1");
Q2.setText("Question 2");
Q2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
Q2ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
.addContainerGap(35, Short.MAX_VALUE)
.addComponent(Q2, javax.swing.GroupLayout.PREFERRED_SIZE, 146, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(13, 13, 13)
.addComponent(Q2, javax.swing.GroupLayout.PREFERRED_SIZE, 47, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
Q2.getAccessibleContext().setAccessibleName("Question2");
Q3.setText("Question 3");
Q3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
Q3ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addContainerGap(32, Short.MAX_VALUE)
.addComponent(Q3, javax.swing.GroupLayout.PREFERRED_SIZE, 149, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(9, 9, 9))
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addComponent(Q3, javax.swing.GroupLayout.DEFAULT_SIZE, 46, Short.MAX_VALUE)
.addContainerGap())
);
Q3.getAccessibleContext().setAccessibleName("Question3");
Q4.setText("Question 4");
Q4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
Q4ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
jPanel4.setLayout(jPanel4Layout);
jPanel4Layout.setHorizontalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel4Layout.createSequentialGroup()
.addContainerGap(38, Short.MAX_VALUE)
.addComponent(Q4, javax.swing.GroupLayout.PREFERRED_SIZE, 147, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
);
jPanel4Layout.setVerticalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addGap(13, 13, 13)
.addComponent(Q4, javax.swing.GroupLayout.PREFERRED_SIZE, 46, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
Q4.getAccessibleContext().setAccessibleName("Question4\n");
Q5.setText("Question 5");
Q5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
Q5ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel5Layout = new javax.swing.GroupLayout(jPanel5);
jPanel5.setLayout(jPanel5Layout);
jPanel5Layout.setHorizontalGroup(
jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel5Layout.createSequentialGroup()
.addGap(37, 37, 37)
.addComponent(Q5, javax.swing.GroupLayout.PREFERRED_SIZE, 147, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(34, Short.MAX_VALUE))
);
jPanel5Layout.setVerticalGroup(
jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel5Layout.createSequentialGroup()
.addGap(13, 13, 13)
.addComponent(Q5, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
Q5.getAccessibleContext().setAccessibleName("Question5");
Bonus.setText("Bonus");
Bonus.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
BonusActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel7Layout = new javax.swing.GroupLayout(jPanel7);
jPanel7.setLayout(jPanel7Layout);
jPanel7Layout.setHorizontalGroup(
jPanel7Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel7Layout.createSequentialGroup()
.addGap(9, 9, 9)
.addComponent(Bonus)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
jPanel7Layout.setVerticalGroup(
jPanel7Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel7Layout.createSequentialGroup()
.addGap(31, 31, 31)
.addComponent(Bonus)
.addContainerGap(34, Short.MAX_VALUE))
);
Exit.setText("Exit");
Exit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
ExitActionPerformed(evt);
}
});
jLabel1.setFont(new java.awt.Font("Vivaldi", 1, 48)); // NOI18N
jLabel1.setText("Quiz");
jLabel2.setFont(new java.awt.Font("Tahoma", 0, 35)); // NOI18N
Start.setText("Start");
Start.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
StartActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel6Layout = new javax.swing.GroupLayout(jPanel6);
jPanel6.setLayout(jPanel6Layout);
jPanel6Layout.setHorizontalGroup(
jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel6Layout.createSequentialGroup()
.addComponent(Start)
.addGap(0, 32, Short.MAX_VALUE))
);
jPanel6Layout.setVerticalGroup(
jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel6Layout.createSequentialGroup()
.addContainerGap()
.addComponent(Start)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
EndQuiz.setText("End Quiz");
EndQuiz.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
EndQuizActionPerformed(evt);
}
});
Timer.setText("jLabel3");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel7, javax.swing.GroupLayout.PREFERRED_SIZE, 110, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(73, 73, 73)
.addComponent(EndQuiz)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 92, Short.MAX_VALUE)
.addComponent(Exit, javax.swing.GroupLayout.PREFERRED_SIZE, 80, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel2)
.addGap(116, 116, 116))
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(Timer)
.addGap(71, 71, 71))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(jLabel2))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(EndQuiz)
.addGap(56, 56, 56))
.addGroup(layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, 76, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addGap(26, 26, 26)
.addComponent(jPanel6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(22, 22, 22)
.addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, 77, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(70, 70, 70)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jPanel7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(Exit, javax.swing.GroupLayout.PREFERRED_SIZE, 44, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(Timer)
.addGap(168, 168, 168))))))
);
pack();
}// </editor-fold>
private void Q1StateChanged(javax.swing.event.ChangeEvent evt) {
// TODO add your handling code here:
}
private void Q1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String Q1 = (String) JOptionPane.showInputDialog( //Question 1
null,
Question.getQuestionMCQ(1),
"Q1",
JOptionPane.QUESTION_MESSAGE,
null,
Question.Options(0),
Question.Options(0)[1]
);
JOptionPane.showMessageDialog(
null,
Question.checkAnswerMCQ (Q1,1));
if (Question.getScore()<1) {
jLabel2.setText(Integer.toString(Question.getScore()));
Q2.setVisible(true); //Q1
}
else {}
}
private void Q2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String Q2 = (String) JOptionPane.showInputDialog( //Question 2
null,
Question.getQuestionMCQ(2),
"Q2",
JOptionPane.QUESTION_MESSAGE,
null,
Question.Options(1),
Question.Options(1)[1]
);
JOptionPane.showMessageDialog(
null,
Question.checkAnswerMCQ (Q2,2));
if (Question.getScore()<2) {
jLabel2.setText(Integer.toString(Question.getScore()));
Q3.setVisible(true); //Q2
}
else {}
}
private void Q3ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String Q3 = JOptionPane.showInputDialog(
null,
Question.getQuestionOE(1),
"Q3",
JOptionPane.QUESTION_MESSAGE);
JOptionPane.showMessageDialog(
null,
Question.checkAnswerOE(Q3, 1));
if (Question.getScore() <3) {
jLabel2.setText(Integer.toString(Question.getScore()));
Q4.setVisible(true); //Q3
}
else {}
}
private void Q4ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String Q4 = JOptionPane.showInputDialog(
null,
Question.getQuestionOE(2),
"Q4",
JOptionPane.QUESTION_MESSAGE);
JOptionPane.showMessageDialog(
null,
Question.checkAnswerOE(Q4, 2));
if (Question.getScore() < 4) {
jLabel2.setText(Integer.toString(Question.getScore()));
Q5.setVisible(true); //Q4
}
else {}
}
private void Q5ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String Q5 = JOptionPane.showInputDialog(
null,
Question.getQuestionOE(3),
"Q5",
JOptionPane.QUESTION_MESSAGE);
JOptionPane.showMessageDialog(
null,
Question.checkAnswerOE(Q5, 3));
if (Question.getScore() < 5) {
jLabel2.setText(Integer.toString(Question.getScore()));
EndQuiz.setVisible(true);
}
else if (Question.getScore()==5) {
Bonus.setVisible(true);
}
else {}
}
private void BonusActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
BonusButtonPicture s =new BonusButtonPicture();
s.setVisible(true);
}
private void ExitActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
System.exit(0);
}
private void StartActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
jLabel2.setText(Integer.toString(Question.restartScore()));
Q1.setVisible(true);
Start.setVisible(false);
}
private void EndQuizActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
JOptionPane.showMessageDialog(null, "Thanks for taking the quiz! You have acheived a score of " +Question.getScore());
int retry = JOptionPane.showConfirmDialog(null, "Do you want to take the quiz again?");
switch (retry) {
case JOptionPane.NO_OPTION: //ends the program
JOptionPane.showMessageDialog(null,"End of quiz");
System.exit(0);
break;
case JOptionPane.YES_OPTION: jLabel2.setText(Integer.toString(Question.restartScore())); //restarts
Question.randomizeQuestionsMCQ();
Question.randomizeQuestionsOpenEnded();
Start.setVisible(true);
break;
case JOptionPane.CLOSED_OPTION: System.exit(0); //closes the program
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
Question.randomizeQuestionsMCQ();
Question.randomizeQuestionsOpenEnded();
/* 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(QuizGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(QuizGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(QuizGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(QuizGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(() -> {
new QuizGUI().setVisible(true);
});
Q1.setVisible(false);
Q2.setVisible(false);
Q3.setVisible(false);
Q4.setVisible(false);
Q5.setVisible(false);
Bonus.setVisible(false);
EndQuiz.setVisible(false);
}
// Variables declaration - do not modify
private static javax.swing.JButton Bonus;
private static javax.swing.JButton EndQuiz;
private javax.swing.JButton Exit;
private static javax.swing.JButton Q1;
private static javax.swing.JButton Q2;
private static javax.swing.JButton Q3;
private static javax.swing.JButton Q4;
private static javax.swing.JButton Q5;
private static javax.swing.JButton Start;
private static javax.swing.JLabel Timer;
private javax.swing.JButton jButton4;
private javax.swing.JLabel jLabel1;
private static javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JPanel jPanel5;
private javax.swing.JPanel jPanel6;
private javax.swing.JPanel jPanel7;
// End of variables declaration
}
错误出现在主方法
中 public static void main(String args[]) {
//code
Q1.setVisible(false); //Error here
Q2.setVisible(false);
Q3.setVisible(false);
Q4.setVisible(false);
Q5.setVisible(false);
Bonus.setVisible(false);
EndQuiz.setVisible(false);
}
提前致谢！
答案 0 :(得分：0)
您正在初始化类的构造函数内的按钮，该按钮在
之后调用 Q1.setVisible(false);
Q2.setVisible(false);
Q3.setVisible(false);
Q4.setVisible(false);
Q5.setVisible(false);
Bonus.setVisible(false);
EndQuiz.setVisible(false);
导致异常的部分代码。您需要做的是将此代码段包含在
中/* Create and display the form */
java.awt.EventQueue.invokeLater(() -> {
new QuizGUI().setVisible(true);
});
应该没问题。