制作一个JFrame按钮，创建一个警报对话框.Java - Netbeans

Question

我使用NetBeans IDE，因为你可能知道有一个JFrame创建者插件(它是预安装的)我用它来制作JFrames(因为我懒得自己做=/)。如果在JFrame中创建按钮，它将为事件代码生成一个区域。我想知道我需要输入什么代码来生成警报对话框。下面是在创建swing/awt组件或JFrame时预生成的内容:

    public class NewJFrame extends javax.swing.JFrame {
public NewJFrame() {
    initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {
    jDialog2 = new javax.swing.JDialog();
    jButton1 = new javax.swing.JButton();
    javax.swing.GroupLayout jDialog2Layout = new javax.swing.GroupLayout(jDialog2.getContentPane());
    jDialog2.getContentPane().setLayout(jDialog2Layout);
    jDialog2Layout.setHorizontalGroup(
        jDialog2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    jDialog2Layout.setVerticalGroup(
        jDialog2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 300, Short.MAX_VALUE)
    );
    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle(">:D");
    setResizable(false);
    addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
        public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            formAncestorMoved(evt);
        }
        public void ancestorResized(java.awt.event.HierarchyEvent evt) {
        }
    });
    jButton1.setText("Press Me :D");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });
    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 349, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 180, Short.MAX_VALUE)
    );
    pack();
    setLocationRelativeTo(null);
}// </editor-fold>                        
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    //This is the area for the code dialog code
}                                        
private void formAncestorMoved(java.awt.event.HierarchyEvent evt) {                                   
    // 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);
        }
    });
}

你有没有看到Button1ActionPerformed这个东西????这就是代码的位置。我需要的代码，将创建一个新的警报对话框(javax.swing.JDialog)

Thanks in advance

Answer 1

听起来你可能想要一个JOptionPane消息对话框…

试试这个:

JOptionPane.showMessageDialog(null, "<your message here...>", "Alert", JOptionPane.ERROR_MESSAGE);

对于你的例子，这就是你的action performed方法的样子:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    JOptionPane.showMessageDialog(null, "<your message here...>", "Alert", JOptionPane.ERROR_MESSAGE);        
}

注意没有"变量"来存储JOptionPane对象，它是在JOptionPane类上调用的静态方法。每次你想要提醒/确认/输入等。对话框，使用JOptionPane类的静态成员动态生成一个。

Answer 2

这是我看到的

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() {
    jOptionPane1 = new javax.swing.JOptionPane();
    jButton1 = new javax.swing.JButton();
    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle(">:D");
    setResizable(false);
    addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
        public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            formAncestorMoved(evt);
        }
        public void ancestorResized(java.awt.event.HierarchyEvent evt) {
        }
    });
    jButton1.setText("Press Me :D");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });
    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 353, javax.swing.GroupLayout.PREFERRED_SIZE)
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(0, 45, Short.MAX_VALUE)
                .addComponent(jOptionPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(0, 46, Short.MAX_VALUE)))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 180, Short.MAX_VALUE)
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jOptionPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(0, 0, Short.MAX_VALUE)))
    );
    pack();
    setLocationRelativeTo(null);
}// </editor-fold>                        
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
//jOptionPane.showMessageDialog(null, "<your message here...>", "Alert", jOptionPane.ERROR_MESSAGE);        
}                                        
private void formAncestorMoved(java.awt.event.HierarchyEvent evt) {                                   
    // 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.JButton jButton1;
private javax.swing.JOptionPane jOptionPane1;
// End of variables declaration                   

}