DrawingPanel中刷新图片扩展了JPanel

我必须在软件底部加载一个小图标。只是有一个加载/确定/错误图标。正如“http://www.article.kth.se/~lindsey/JavaCourse/Book/Part1/Java/Chapter06/images.html”上的建议，我创建了一个扩展 JPanel 的 dwowing 面板。

class drawingPanel extends JPanel
{
    Image img;

    drawingPanel (Image img){
        this.img = img;
    }

    public void paintComponent (Graphics g) {
        super.paintComponent (g);

        // Use the image width & height to find the starting point
        int imgX = getSize ().width/2 - img.getWidth (this);
        int imgY = getSize ().height/2 - img.getHeight (this);

        //Draw image centered in the middle of the panel    
        g.drawImage (img, imgX, imgY, this);
    } // paintComponent

}

我通过以下方式初始化组件：

// Grab the image.
Image img = new ImageIcon(iconPath+"ok.png").getImage();
// Create an instance of DrawingPanel
iconPanel = new drawingPanel(img);

一切正常，但在运行时我希望能够更改面板内的图标。我尝试了以下所有方法，但都没有成功查看新图片：

Image img = new ImageIcon(iconPath+"loading.gif").getImage();
// Create a new  instance of DrawingPanel
this.iconPanel = new drawingPanel(img);
this.iconPanel.repaint();
this.iconPanel.revalidate();
this.iconPanel.repaint();
this.repaint();
this.revalidate();

（我尝试这样做是因为我编写代码的类是包含图标面板的 JPanel 的另一个扩展。知道为什么我无法更改图片吗？

谢谢， 斯特凡诺

首先不要以小名称开头。改名drawingPanel to DrawingPanel.

我尝试根据您的描述制作一个简单的演示，效果很好。面板中的图像正在完美变化。

public class Demo {

    public Demo() {
        JFrame frame = new JFrame();
        frame.setSize(400, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        // Grab the image.
        Image img = new ImageIcon("1.png").getImage();
        // Create an instance of DrawingPanel
        final DrawingPanel iconPanel = new DrawingPanel(img);

        frame.add(iconPanel, BorderLayout.CENTER);

        JButton button = new JButton("Change image..");
        frame.add(button, BorderLayout.NORTH);

        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                iconPanel.setImg(new ImageIcon("2.png").getImage());
                iconPanel.repaint();
            }
        });

        frame.setVisible(true);
    }

    public static void main(String[] args){
        new Demo();
    }
}

class DrawingPanel extends JPanel {
    Image img;

    DrawingPanel(Image img) {
        this.img = img;
    }

    public void setImg(Image img) {
        this.img = img;
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        // Use the image width & height to find the starting point
        int imgX = getSize().width / 2 - img.getWidth(this);
        int imgY = getSize().height / 2 - img.getHeight(this);

        // Draw image centered in the middle of the panel
        g.drawImage(img, imgX, imgY, this);
    } // paintComponent

}

我所做的更改是添加一个 setter 方法img in DrawingPanel班级。所以不要创建新的DrawingPanel您只需使用新图像调用 settIng() ，然后调用 Paint 来绘制新图像。