将JPanel中的当前图像替换为另一幅图像

Question

I´m writing a program where images are displayed on a JPanel, but I´m having trouble replacing the existing image when I open a new one. Is there a easy way to remove the old image from the ImageIcon and replace with the new one? I thought that something like mp.remove(pic); would work here, but it says that it´s not supported for ImageIcon?

class MapPanel extends JPanel {

public MapPanel(String filename) {
    if(mp == null) {
    pic = new ImageIcon(filename);
    int w = pic.getIconWidth();
    int h = pic.getIconHeight();
    setPreferredSize(new Dimension(w, h));
    setMinimumSize(new Dimension(w, h));
    setMaximumSize(new Dimension(w, h));
    setLayout(null);
}
    else { int confirm = 
JOptionPane.showConfirmDialog(MapProgram.this, "Unsaved changes, " + 
"do you really want to open a new map?",
            "New map", JOptionPane.OK_CANCEL_OPTION);
            if (confirm != JOptionPane.OK_OPTION)
                return;     

    // Remove the current image and display the new one choosen 
    // from the JFileChooser.


    }       
}
protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(pic.getImage(), 0, 0, this);
    }

}

Answer 1

Why are you using ImageIcon at all? It appears you want to draw an Image in a JPanel, not sure why you are using ImageIcon. Use ImageIO.read() to read the file chosen by the file chooser as an BufferedImage. Set the image to a member variable, then in paintComponent() instead of pic.getImage(), use your member variable. After a file is chosen and you set your member variable to the new file call repaint().

https://docs.oracle.com/javase/8/docs/api/javax/imageio/ImageIO.html#read-java.io.File-

Also, setting preferredSize, min size, and max size may or may not do anything. It all depends on what layout manager the container you put this JPanel in is using.

Answer 2

Not sure if this will work for what you want to do but give it a try.

g.drawImage(new ImageIcon(filename).getImage(), 0, 0, this);

or just pass in an Image there.