Java 帧关闭命令\u变量_Java - Fatal编程技术网

Java 帧关闭命令\u变量

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Java 帧关闭命令\u变量,java,Java,所以，我的第一篇文章我学习Java。我有个问题。我想在尝试关闭窗口0帧时打开一个弹出窗口所以，我插入这个。来自教师的示例代码。请检查一下来了 private void formWindowClosing(java.awt.event.WindowEvent evt) { int reply = JOptionPane.showConfirmDialog(this, "Really close?"

所以，我的第一篇文章

我学习Java。我有个问题。我想在尝试关闭窗口0帧时打开一个弹出窗口

所以，我插入这个。来自教师的示例代码。请检查一下来了

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
            int reply = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
            if (reply == JOptionPane.YES_OPTION) {
                this.dispose();
            if (reply == JOptionPane.NO_OPTION)
                this.setVisible(true);
            }
    }

它什么也不做。没有弹出窗口提供所需内容

您的方法很可能永远不会被调用。您需要使用WindowListener。下面是如何设置它的：

JFrame mainFrame = new JFrame(); //that's your frame

mainFrame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE) //enable windowlistener handling

mainFrame.addWindowListener(new WindowListener() { //you need to add a windowlistener

        @Override
        public void windowClosing(WindowEvent e) {
            formWindowClosing(e); //call your method
        }

        @Override 
        public void windowOpened(WindowEvent e) {}

        @Override 
        public void windowClosed(WindowEvent e) {}

        @Override 
        public void windowIconified(WindowEvent e) {}

        @Override 
        public void windowDeiconified(WindowEvent e) {}

        @Override 
        public void windowActivated(WindowEvent e) {}

        @Override 
        public void windowDeactivated(WindowEvent e) {}

    });

当程序请求退出时，这将调用关闭方法。

我使用NetBeans平台。因此，我的代码如下：

package my.exercise21;

导入javax.swing.JOptionPane

/** * *@作者管理员 */ 公共类Exercise21扩展了javax.swing.JFrame{

/**
 * Creates new form Exercise21
 */
public Exercise21() {
    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() {

    jMenuBar1 = new javax.swing.JMenuBar();
    jMenu1 = new javax.swing.JMenu();
    jMenuItem1 = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);

    jMenu1.setText("File");

    jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK));
    jMenuItem1.setText("Exit");
    jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuItem1ActionPerformed(evt);
        }
    });
    jMenu1.add(jMenuItem1);

    jMenuBar1.add(jMenu1);

    setJMenuBar(jMenuBar1);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 279, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
    dispose();
    // TODO add your handling code here:
}                                          

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
        int reply = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
        if (reply == JOptionPane.YES_OPTION) {
            this.dispose();
        if (reply == JOptionPane.NO_OPTION)
            this.setVisible(true);
        }
}   

/**
 * @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 | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Exercise21.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(() -> {
        new Exercise21().setVisible(true);
    });
}

// Variables declaration - do not modify                     
private javax.swing.JMenu jMenu1;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem jMenuItem1;
// End of variables declaration

/**
*创建新表单练习21
*/
公众锻炼21（）{
初始化组件（）；
}
/**
*从构造函数中调用此方法来初始化表单。
*警告：不要修改此代码。此方法的内容始终为
*由表单编辑器重新生成。
*/
@抑制警告（“未选中”）
//                           
私有组件（）{
jMenuBar1=newjavax.swing.JMenuBar（）；
jMenu1=newjavax.swing.JMenu（）；
jMenuItem1=newjavax.swing.JMenuItem（）；
setDefaultCloseOperation（javax.swing.WindowConstants.DO\u NOTHING\u ON\u CLOSE）；
setText（“文件”）；
setAccelerator（javax.swing.KeyStroke.getKeyStroke（java.awt.event.KeyEvent.VK_X，java.awt.event.InputEvent.CTRL_MASK））；
jMenuItem1.setText（“退出”）；
jMenuItem1.addActionListener（新java.awt.event.ActionListener（）{
public void actionPerformed（java.awt.event.ActionEvent evt）{
jMenuItem1执行的操作（evt）；
}
});
jMenu1.add（jMenuItem1）；
jMenuBar1.add（jMenu1）；
setJMenuBar（jMenuBar1）；
javax.swing.GroupLayout=newjavax.swing.GroupLayout（getContentPane（））；
getContentPane（）.setLayout（布局）；
layout.setHorizontalGroup(
createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
.addGap（0，400，短。最大值）
);
layout.setVerticalGroup(
createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
.addGap（0，279，短。最大值）
);
包装（）；
}//                         
private void jMenuItem1ActionPerformed（java.awt.event.ActionEvent evt）{
处置（）；
//TODO在此处添加您的处理代码：
}                                          
私有void formWindowClosing（java.awt.event.WindowEvent evt）{
int reply=JOptionPane.showConfirmDialog（此选项为“真的关闭？”，“关闭？”，JOptionPane.YES\u NO\u选项）；
if（reply==JOptionPane.YES\u选项）{
这个。dispose（）；
if（reply==JOptionPane.NO_选项）
此.setVisible（true）；
}
}   
/**
*@param指定命令行参数
*/
公共静态void main（字符串参数[]）{
/*设置Nimbus的外观和感觉*/
//
/*如果Nimbus（在JavaSE6中引入）不可用，请使用默认的外观。
*详情请参阅http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
*/
试一试{
for（javax.swing.UIManager.LookAndFeelInfo:javax.swing.UIManager.getInstalledLookAndFeels（））{
if（“Nimbus”.equals（info.getName（）））{
setLookAndFeel（info.getClassName（））；
打破
}
}
}catch（ClassNotFoundException |实例化Exception | IllegalacessException | javax.swing.UnsupportedLookAndFeelException ex）{
getLogger（Exercise21.class.getName（））.log（java.util.logging.Level.SEVERE，null，ex）；
}
//
//
/*创建并显示表单*/
java.awt.EventQueue.invokeLater（（）->{
新的Exercise21（）.setVisible（true）；
});
}
//变量声明-不修改
私有javax.swing.JMenu jMenu1；
私有javax.swing.JMenuBar jMenuBar1；
私有javax.swing.JMenuItem jMenuItem1；
//变量结束声明

}

我想我的问题在于没有调用JOptionPane库

我刚刚解决了这个问题。感谢您的参与和您的灵感

/*
 * To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package my.exercise21;

import javax.swing.JOptionPane;

/**
*
* @author Administrator
*/
public class NewJFrame extends javax.swing.JFrame {

/**
 * Creates new form NewJFrame
 */
public NewJFrame() {
    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() {

    jMenuBar1 = new javax.swing.JMenuBar();
    jMenu1 = new javax.swing.JMenu();
    jMenuItem1 = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
    setTitle("Exercise 2.1");
    setCursor(new java.awt.Cursor(java.awt.Cursor.NW_RESIZE_CURSOR));
    addWindowListener(new java.awt.event.WindowAdapter() {
        public void windowClosed(java.awt.event.WindowEvent evt) {
            formWindowClosed(evt);
        }
        public void windowClosing(java.awt.event.WindowEvent evt) {
            formWindowClosing(evt);
        }
    });

    jMenu1.setText("File");

    jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK));
    jMenuItem1.setText("Exit");
    jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuItem1ActionPerformed(evt);
        }
    });
    jMenu1.add(jMenuItem1);

    jMenuBar1.add(jMenu1);

    setJMenuBar(jMenuBar1);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 279, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

private void formWindowClosed(java.awt.event.WindowEvent evt) {                                  
    // TODO add your handling code here:
}                                 

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
    int r = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
    if (r == JOptionPane.YES_OPTION) {
            dispose(); // This closes the program
        if (r == JOptionPane.YES_OPTION)
            setVisible(false); // This just hides the window but program keeps running.
    }// TODO add your handling code here:
}                                  

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
    dispose();        // TODO add your handling code here:
}                                          

/**
 * @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.JMenu jMenu1;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem jMenuItem1;
// End of variables declaration

/*
*要更改此许可证标题，请在“项目属性”中选择“许可证标题”。
*要更改此模板文件，请选择工具|模板
*然后在编辑器中打开模板。
*/
包我的练习21；
导入javax.swing.JOptionPane；
/**
*
*@作者管理员
*/
公共类NewJFrame扩展了javax.swing.JFrame{
/**
*创建新表单NewJFrame
*/
公共NewJFrame（）{
初始化组件（）；
}
/**
*从构造函数中调用此方法来初始化表单。
*警告：不要修改此代码。此方法的内容始终为
*由表单编辑器重新生成。
*/
@抑制警告（“未选中”）
//                           
私有组件（）{
jMenuBar1=newjavax.swing.JMenuBar（）；
jMenu1=newjavax.swing.JMenu（）；
jMenuItem1=newjavax.swing.JMenuItem（）；
setDefaultCloseOperation（javax.swing.WindowConstants.DO\u NOTHING\u ON\u CLOSE）；
设定标题（“练习2.1”）；
setCursor（新java.awt.Cursor（java.awt.Cursor.NW_RESIZE_Cursor））；
addWindowListener（新java.awt.event.WindowAdapter（）{
公共无效windowClosed（java.awt.event.WindowEvent evt）{
窗体窗口关闭（evt）；
}
公共无效窗口关闭（java.awt.event.WindowEvent evt）{
窗体窗口关闭（evt）；
}
});
setText（“文件”）；
setAccelerator（javax.swing.KeyStroke.getKeyStroke（java.awt.event.KeyEvent.VK_X，java.awt.event.InputEvent.CTRL_MASK））；
jMenuItem1.setText（“退出”）；
jMenuItem1.addActionListener（新java.awt.event.ActionListener（）{
public void actionPerformed（java.awt.event.ActionEvent evt）{
jMenuItem1ActionPer