java - 如何在 java 中重置 JFrame

Question

我是java初学者。我有如下 ImageFrame 类:

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);
    }   
}

但是当我按下灰度子菜单时，图像并没有转换成灰度，但是当我最小化窗口并最大化它时，图像变成了灰度。我认为这是因为窗口没有刷新。如何刷新它？

Answer 1

调用repaint在您的 Action 监听器中的 ImageComponent 上。