Question

每次打开和关闭我的应用程序时，我都希望出现一个小窗口，等待几秒钟。当我启动程序时，一切正常。但是在应用程序运行时创建框架的新实例后，我得到的只是一个白屏。我怎样才能解决这个问题？请不要介意标签的德语内容。谢谢！

public class WaitingFrame extends JFrame
{
    public WaitingFrame(boolean closing)
    {
        // Window setup. Set title unnecessary 'cause of setUndecorated(true)
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setLocation((int) screenSize.getWidth() /3, (int) screenSize.getHeight() / 4);
        setSize(350,200);
        setLayout(new BorderLayout());
        GridBagConstraints c = new GridBagConstraints();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        setUndecorated(true);
        this.getContentPane().setBackground(Color.WHITE);

        // Creating Java Swing Components
        JPanel bottom = new JPanel(new GridBagLayout());
        bottom.setBackground(Color.WHITE);
        ImageIcon icon = new ImageIcon("db.png");
        JLabel first = new JLabel();
        JLabel second = new JLabel("%");
        JLabel third = new JLabel();

        int waitingTime;
        if(!closing)
        {
            first.setText("Programm startet in ");
            third.setText(" Sekunden!");
            waitingTime=60;
        }   
        else
        {
            first.setText("Programm wird in ");
            third.setText(" Sekunden beendet!");
            waitingTime=30;
        }

        bottom.add(first,c);
        c.gridx = 1;
        bottom.add(second,c);
        c.gridx = 2;
        bottom.add(third,c);

        JButton cancel = new JButton("in den Hintergrund");
        cancel.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                minimize();
            }
        });

        c.gridwidth=3;
        c.gridx=0;
        c.gridy=1;

        bottom.add(cancel,c);

        this.getContentPane().add(bottom,BorderLayout.SOUTH);
        this.getContentPane().add(new JLabel(icon),BorderLayout.CENTER);
        setVisible(true);

        for(int i=5;i>0;i--)
        {
            second.setText(String.valueOf(i));
            try {
            TimeUnit.SECONDS.sleep(1);
            }
            catch(InterruptedException sl) {}
        }

        this.dispose();

        if(closing)
            System.exit(0);
    }

    private void minimize()
    {
        this.setState(Frame.ICONIFIED);
    }
}

我知道直到现在可能不会使用某些变量

这是关闭应用程序时得到的一切。 WaitingFrame

JFrame有时只会返回白屏

0 个答案: