如何在java中重置JFrame

Question

I am a beginner to java. I have ImageFrame class as follows:

public class ImageFrame extends JFrame {
    private static final long serialVersionUID = 1L;

    public static final int DEFAULT_WIDTH = 1365;
    public static final int DEFAULT_HEIGHT = 730;

    GettingImage getimg = new GettingImage();
    private BufferedImage image = getimg.getImage();

    final ImageProcessing operation = new ImageProcessing(image);

    public ImageFrame(){
        setTitle("ImageTest");
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        JMenu process = new JMenu("Process");

        JMenuItem greyscale = new JMenuItem("greyscale");
        process.add(greyscale);

        //adding action listener to menu items
        greyscale.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent e)
                {
                    image = operation.greyscale();
                    System.out.println("greyscale is pressed");  
                }
            }
        );

        JMenuBar bar = new JMenuBar();
        setJMenuBar(bar);
        bar.add(process);

        setSize(1365, 730);
        setVisible(true);

        ImageComponent component = new ImageComponent(image);
        add(component);
    }   
}

But the image is not converted into greyscale when I press the greyscale submenu but when I minimized the window and maximize it then the image is changed into greyscale. I think it is due to the fact that the window is not refreshed. How do I refresh it?

Answer 1

在动作侦听器中的ImageComponent上调用重绘 。

Answer 2

尝试在动作侦听器的末尾调用repaint（）

Answer 3

好吧，因为当最小化窗口然后最大化它时，您可以尝试.dispose（）它关闭窗口或者您可以编写自己的重启方法来将变量设置为它们的起始值。