【发布时间】：2021-04-06 11:04:36
【问题描述】：
NetBeans 12.3 / Java 15.0.2 / Ubuntu 16.04。
我在 NetBeans 中创建了一个 Maven/Java 应用程序，它只有一个 JDialog 和一个调用 dispose() 的按钮。在 NetBeans 中运行它。如果我用角落里的十字关闭它，对话框就会消失，应用程序会关闭/退出。当我用按钮关闭它时，对话框会消失，但应用程序永远不会完成。
对话框上有一个用于关闭的窗口侦听器（由 NetBeans 创建）。监听器调用System.exit(0)。使用调试我可以看到侦听器在一种情况下被执行，但在另一种情况下却没有。对话框默认关闭操作是dispose。
当然我可以只添加一个调用System.exit，但我的印象应该是 dispose 和用角叉关闭对话框应该没有区别？
public class NewJDialog extends javax.swing.JDialog {
/**
* Creates new form NewJDialog
*/
public NewJDialog (java.awt.Frame parent, boolean modal) {
super (parent, modal);
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() {
button1 = new java.awt.Button();
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
button1.setLabel("button1");
button1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
button1ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(261, Short.MAX_VALUE)
.addComponent(button1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(73, 73, 73))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(174, Short.MAX_VALUE)
.addComponent(button1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(103, 103, 103))
);
pack();
}// </editor-fold>
private void button1ActionPerformed(java.awt.event.ActionEvent evt) {
dispose ();
}
/**
* @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 (NewJDialog.class.getName ()).log (java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger (NewJDialog.class.getName ()).log (java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger (NewJDialog.class.getName ()).log (java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger (NewJDialog.class.getName ()).log (java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/*
* Create and display the dialog
*/
java.awt.EventQueue.invokeLater (new Runnable () {
public void run () {
NewJDialog dialog = new NewJDialog (new javax.swing.JFrame (), true);
dialog.addWindowListener (new java.awt.event.WindowAdapter () {
@Override
public void windowClosing (java.awt.event.WindowEvent e) {
System.exit (0);
}
});
dialog.setVisible (true);
}
});
}
// Variables declaration - do not modify
private java.awt.Button button1;
// End of variables declaration
}
【问题讨论】：
-
文档是您的朋友。阅读what dispose() does 和when windowClosing is called。 dispose() 只是破坏窗口，这就是为什么它是许多可能的默认关闭操作之一。 dispose() 不模拟按下系统提供的窗口控件中的关闭按钮。