Can't display image on JPanel

[Ben Jass]

Hey Guys,
Creating a Hangman Game, just started developing the GUI aspect of it.
JPanel covers the JFrame, I set the layout to null, and I'm using the setBounds(x, y, width, height) to position everything on the screen.

However, I have had no luck with being able to display a .png image on the panel?

My setUpGui() method:

 	public void setUpGui() {
		frame = new JFrame("Hangman");
		
		panel = new JPanel();
		panel.setBackground(Color.darkGray);
		panel.setLayout(null);
		
		userField = new JTextField(10);
		userLabel = new JLabel("User Field:");
		userLabel.setForeground(Color.WHITE);
		
		computerField = new JTextField(10);
		computerLabel = new JLabel("Computer Field:");
		computerLabel.setForeground(Color.WHITE);
		
		panel.add(userField);
		panel.add(userLabel);
		userField.getPreferredSize();
		userField.setBounds(100, 400, 100, 30);
		userLabel.getPreferredSize();
		userLabel.setBounds(100, 370, 100, 30);
		
		
		panel.add(computerField);
		panel.add(computerLabel);
		computerField.getPreferredSize();
		computerField.setBounds(280, 400, 100, 30);
		computerLabel.getPreferredSize();
		computerLabel.setBounds(280, 370, 100, 30);
		
		setUserState();
		setComputerState();
		setRound();
		setGuess();
		setDifficultyLabel();
		setHookStatus();
		
		frame.getContentPane().add(panel);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setResizable(false);
		frame.setSize(500, 500);
		frame.setLocationRelativeTo(null);
		frame.setVisible(true);
	}

setHookStatus() method:

	public void setHookStatus() {
			userHook = new ImageIcon("images/HangMan Hook.png");
			userHookLabel = new JLabel(userHook);
			panel.add(userHookLabel);
			userHookLabel.setBounds(80, 150, 150, 150);
	}

Nothing prints on the screen. I'm using Eclipse and the image is located in the images folder right next to my source code.
I have also tried extending my class to JPanel, and overriding the paintComponent method and call the drawImage(image, x, y, panel), but this hasn't worked at all either. any thoughts?

[Fred Kleinschmidt]

1. You really should use a LayoutManager!
2. Have you checked the result of the call

userHook = new ImageIcon("images/HangMan Hook.png");

to see that it is successful?

[Ben Jass]

I'm not using the layout managers because it's not able to align the components the way I imagined for this project. How would I display the result of the call for an image icon object?

[Joel McNary]

A layout manager would be better; GridBagLayout is my favorite and would work well in your case here, but it takes a bit of patience to understand all of its nuances. But that is beside the point of your question.

To check the result, just call System.out.println(userHook) and see what you get. Or add a breakpoint in eclipse and check the value of the variable. The big question is, "Is it null?"

[Ben Jass]

I'll look into GridBagLayout, thanks.

The result was it printed the name of the location shown: images/HangMan Hook.png
It's not null.

[Fred Kleinschmidt]

Are you sure there is anything in the ImageIcon? What is the result of

System.out.println( userHook.getIconWidth + "  x " + userHook.getIconHeight() );

[Ben Jass]

The results that were printed were: -1 and 1.

So I checked the methods that could be called on an ImageIcon object and nothing indicates a setSize() method.

The actual file dimensions:
Width: 110
Height: 136

So I tried extending from JPanel, overriding the paintComponent() method:

public void paintComponent(Graphics g) {
		userHook.paintIcon(panel, g, 150, 300);
	}

My paintComponent() method never ran?

[Fred Kleinschmidt]

That result means that your file (images/HangMan Hook.png) does not contain a valid image.

[Ben Jass]

By invalid image, do you mean there is something wrong with the actual file itself? Or it is not able to locate the file? I made the file in paint.

[Ben Jass]

Thanks Everyone for the help, I was able to get it to print using

try {
     BufferedImage img = ImageIO.read("");
} catch {

JLabel label = new JLabel(img);

But one last question, does anyone know why my paintComponent Method is never called? I've tried repaint() and revalidate()

[Paul Clapham]

Considering we've only ever seen it by itself, without any context at all, there could be any number of reasons why it's not being called. It's pretty clear that it's a method of some object which isn't part of your GUI -- or perhaps it doesn't override any method of JPanel -- anyway you see what I mean, it would be better to look at how the method is used rather than guessing.

[Fred Kleinschmidt]

You haven't shown us enough code to be able to answer this, especially the declaration of the class that contains your paintComponent method. But to hazard a guess, perhaps your class extends JFrame (which does not have a paintCoimponent method), or your paintComponent method has a different signature than its superclass' method.

[Les Morgan]

Ben,

It probably did run, but nothing is really being done in it that is of any use. Generally speaking make a call to super.paintComponent(g) so it will erase your screen, then have everything written back to it afterward. What you are showing, as has already been stated, is not enough to know what is going on. IMO: you will have much better luck using a BufferedImage and drawing that onto the context of the JPanel using drawImage as described in the API--g.drawImage where g is the graphics context of the JPanel. You can get a BufferedImage using ImageIO.

Les

Here is an example:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.net.URL;

import javax.imageio.ImageIO;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class urlJunk implements ActionListener{
  MyJPanel p;
  Timer t;
  urlJunk(){
    t = new Timer(2000, this);
    JFrame f = new JFrame("Junk");
    f.setUndecorated(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setBackground(new Color(0,0,0,0));
    p = new MyJPanel();
    f.add(p);
    f.pack();
    f.setVisible(true);
    t.start();
  }
  public static void main(String[] args){
    new urlJunk();
  }
  public void actionPerformed(ActionEvent e){
    BufferedImage bi;
    try{
      bi = ImageIO.read(new URL("http://www.phantomfootball.com/2009_old_site/images/download/logos/2009_Official_Cathedral_Phantom_Logo_Transparent_Background.png"));
      p.setBI(bi);
    }catch(Exception ex){
      ex.printStackTrace();
    }    
  }
  class MyJPanel extends JPanel{
    BufferedImage bi;
    MyJPanel(){
      try{
        bi = ImageIO.read(new URL("http://i52.tinypic.com/i3b40n.png"));
        this.setPreferredSize(new Dimension(bi.getWidth(), bi.getHeight()));
        this.setBackground(new Color(0,0,0,0));
      }catch(Exception e){
        e.printStackTrace();
      }
    }
    public void setBI(BufferedImage bi){
      this.bi = bi;
      t.stop();
      this.repaint();
    }
    public void paintComponent(Graphics g){
      super.paintComponent(g);
      g.drawImage(bi, 0, 0, 300, 300, this);
    }
  }
}

Ben Jass wrote:The results that were printed were: -1 and 1.

So I checked the methods that could be called on an ImageIcon object and nothing indicates a setSize() method.

The actual file dimensions:
Width: 110
Height: 136

So I tried extending from JPanel, overriding the paintComponent() method:

public void paintComponent(Graphics g) {
		userHook.paintIcon(panel, g, 150, 300);
	}

My paintComponent() method never ran?

[Fred Kleinschmidt]

As Les Morgan's example shows, your first statement in paintComponent() should be

 super.paintComponent(g);

But then I don't think you even need to override the paintComponent() method at all. You set the Icon to be the icon in the userHookLabel child, so the label will be automatically rendered when your component is rendered.

[Les Morgan]

Ben,

When you get a -1, and I am not sure about the 1, it means the load has not completed yet. So you are basically trying to render a null to the graphics context. In my experience once that happens, you will not have a completed image for the life of the run. So even though you try to render, and your paintComponent works, there isn't any image to render--nothing happens.

Les

Ben Jass wrote:The results that were printed were: -1 and 1.

So I checked the methods that could be called on an ImageIcon object and nothing indicates a setSize() method.

The actual file dimensions:
Width: 110
Height: 136

So I tried extending from JPanel, overriding the paintComponent() method:

public void paintComponent(Graphics g) {
		userHook.paintIcon(panel, g, 150, 300);
	}

My paintComponent() method never ran?

[Les Morgan]

Yep, if you use an ImageIcon and a JLabel, then you have nothing to do with the paintComponent of the JPanel, and since you are using a "null" layout manager, you don't even have to worry about resizing your image to fit fully onto the JLabel.

Fred Kleinschmidt wrote:As Les Morgan's example shows, your first statement in paintComponent() should be

 super.paintComponent(g);

But then I don't think you even need to override the paintComponent() method at all. You set the Icon to be the icon in the userHookLabel child, so the label will be automatically rendered when your component is rendered.