在 JFrame 中将图像绘制到 JPanel

Question

I am designing a program that contains two JPanels within a JFrame, one is for holding an image, the other for holding GUI components(Searchfields etc). I am wondering how do I draw the Image to the first JPanel within the JFrame?

Here is a sample code from my constructor :

public UITester() {
    this.setTitle("Airplane");
    Container container = getContentPane();
    container.setLayout(new FlowLayout());
    searchText = new JLabel("Enter Search Text Here");
    container.add(searchText);
    imagepanel = new JPanel(new FlowLayout());
    imagepanel.paintComponents(null);
   //other constructor code

}

public void paintComponent(Graphics g){
    super.paintComponents(g);
    g.drawImage(img[0], -50, 100, null);
}

I was trying to override the paintComponent method of JPanel to paint the image, but this causes a problem in my constructor when I try to write :

imagepanel.paintComponents(null);

As it will only allow me to pass the method null, and not Graphics g, anybody know of a fix to this method or another method i can use to draw the image in the JPanel? Help is appreciated! :)

All the best and thanks in advance! Matt

Answer 1

I'd like to suggest a more simple way,

  image = ImageIO.read(new File(path));
  JLabel picLabel = new JLabel(new ImageIcon(image));

Yayy! Now your image is a swing component ! add it to a frame or panel or anything like you usually do! Probably need a repainting too , like

  jpanel.add(picLabel);
  jpanel.repaint(); 

Answer 2

You can use the JLabel.setIcon() to place an image on the JPanel as shown here .

On the other hand, if you want to have a panel with a background, you can take a look at this tutorial.

Answer 3

There is no need to manually invoke paintComponent() from a constructor. The problem is that you passing null for a Graphics object. Instead, override paintComponent() and you use the Graphics object passed in to the method you will be using for painting. Check this tutorial . Here is an example of JPanel with image:

class MyImagePanel extends JPanel{ 
    BufferedImage image;
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        if(image != null){
            g.drawImage(image, 0, 0, this);
        }
    }
}