Java / Swing -> Creating a notification JFrame, and the error “The frame is displayable”

问题

Ok, I am not that versed in Java / Swing, and I am running into a problem. My application is throwing this error: "Exception in thread "AWT-EventQueue-0" java.awt.IllegalComponentStateException: The frame is displayable." Google isn't turning up much information on this error, and a quick search of StackOverflow is not showing anything yet.

What I am trying to do: just implement translucent windows using the code from the tutorials. That's it. I plan to use this as a general window for displaying notifications, such as "This program has not been run in 30 days" down near the system tray.

Are there any experienced Java / Swing gurus out there who can spot my beginner's mistake?

Thank You.

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package energizingemerald;

/**
 *
 */
import java.awt.*;
import javax.swing.*;
import static java.awt.GraphicsDevice.WindowTranslucency.*;

public class NotificationFrame extends javax.swing.JFrame {

    /**
     * Creates new form NotificationFrame
     */
    public NotificationFrame() {
        initComponents();

        this.setLayout(new GridBagLayout());
        this.setUndecorated(true);
        this.setSize(300,200);
        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


        this.setOpacity(0.50f);


    }

    /**
     * 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() {

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        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, 300, Short.MAX_VALUE)
        );

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

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

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new NotificationFrame().setVisible(true);
            }
        });
    }




    // Variables declaration - do not modify                     
    // End of variables declaration                   
}

回答1:

• +1 thanks for this thread, your code solved quite correctly undecorated conatiner, everything is about correct ordering of methods (wooolaaa we are back to Java_1.4.2 edges)

• but bug still is there, isn't possible to create decorated JFrame with changed Look And Feel

• based on proper ordering of methods

import java.awt.*;
import javax.swing.*;

public class TranslucentWindow extends JFrame {

    private static final long serialVersionUID = 1L;

    public TranslucentWindow() {
        super("Test translucent window");
        setLayout(new FlowLayout());
        add(new JButton("test"));
        add(new JCheckBox("test"));
        add(new JRadioButton("test"));
        add(new JProgressBar(0, 100));
        JPanel panel = new JPanel() {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(400, 300);
            }
            private static final long serialVersionUID = 1L;

            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.red);
                g.fillRect(0, 0, getWidth(), getHeight());
            }
        };
        panel.add(new JLabel("Very long textxxxxxxxxxxxxxxxxxxxxx "));
        add(panel);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setUndecorated(true);
        pack();
        setLocationRelativeTo(null);
        setOpacity(0.70f);
    }

    public static void main(String[] args) {
        try {
            for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        //JFrame.setDefaultLookAndFeelDecorated(true);
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                Window w = new TranslucentWindow();
                w.setVisible(true);
            }
        });
    }
} 

回答2:

The error you are getting is calling setUndecorated(true) after the frame is made displayable by calling pack(). Call setUndecorated before pack and it should work.

来源：https://stackoverflow.com/questions/16698699/java-swing-creating-a-notification-jframe-and-the-error-the-frame-is-disp