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A class that extends JPanel, that i want to add with CENTER proprity in my JFrame that is a BorderLayout

I have a class named panneau :
public class Panneau extends JPanel {
public void paintComponent(Graphics g){
try {
Image img = ImageIO.read(new File("src/disantiammo/image/image.png"));
g.drawImage(img, 0, 0, this);
} catch (IOException e) {
e.printStackTrace();
}
}
}
//for now it is not doing anything but it will...
In the JFrame I have a few JPanels with others elements.
The JFrame's layout is a BorderLayout
The probleme is this pan has to be "java.awt.BorderLayout.CENTER", I can only place it this way :
this.setContentPane(new Panneau());
How do I do to place it in "CENTER"?
I tried things like
this.getContentPane().add(new Panneau(), java.awt.BorderLayout.CENTER);
Nothing seems to work the only thing I can do is to place "panneau" instead of what's inside my JFrame.
EDIT :
This may sound as a really simple thing, but I don't understand why I can't do that, that I'm stuck trying doing it.
I have jDialog, it is in BorderLayout, in "south", "north" and "center" I have jPanel with elements (with nothing in the "center"'s jPanel.
"center" jPanel is called Map.
I'm thing things like :
in the main
Graphics t = Map.getGraphics();
paintComponent(t);
not in the main.
public void paintComponent(Graphics g){
super.paintComponents(g);
g.drawLine(0, 0, 50, 150);
}
I cannot draw anything.

I find that the easiest way to fully center a component is to give the container a GridBagLayout, and then add the single component to that container, but without using any constraints.
Side issue: your code reads in an image in a painting method -- never do this. Instead read the image in once and store it in a variable. Then display it within the painting method. Also be sure to call the super's painting method in your override.
e.g.,
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class CenteredImage extends JPanel {
private static final String IMG_PATH = "https://upload.wikimedia.org/wikipedia/commons/"
+ "thumb/f/f8/Portrait_d%27une_Femme_%C3%A0_sa_Toilette%2C_by_Titian%2C_"
+ "from_C2RMF_retouched.jpg/300px-Portrait_d%27une_Femme_%C3%A0_sa_"
+ "Toilette%2C_by_Titian%2C_from_C2RMF_retouched.jpg";
private BufferedImage img;
public CenteredImage(BufferedImage img) {
this.img = img;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, this);
}
}
#Override
public Dimension getPreferredSize() {
Dimension prefSize = super.getPreferredSize();
if (isPreferredSizeSet() || img == null) {
return super.getPreferredSize();
}
return new Dimension(img.getWidth(), img.getHeight());
}
private static void createAndShowGui() {
BufferedImage img = null;
try {
URL imgUrl = new URL(IMG_PATH);
img = ImageIO.read(imgUrl);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
CenteredImage mainPanel = new CenteredImage(img);
JFrame frame = new JFrame("CenteredImage");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(800, 650));
frame.getContentPane().setLayout(new GridBagLayout());
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
Edit: use of a wrapper JPanel as noted in comments:
You state in comments:
Thank you for you anwser but I meant something else : There is : a JFrame/JDialog in borderLayout, I want to put "panneau" inside of it in the center position of it, maybe I don't know how to say it ... there are elements in "south", "north" ect ...
then wrap the image producing JPanel in another JPanel that uses GridBagLayout and add the wrapper JPanel to the JFrame BorderLayout.CENTER
private static void createAndShowGui() {
BufferedImage img = null;
try {
URL imgUrl = new URL(IMG_PATH);
img = ImageIO.read(imgUrl);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
CenteredImage centeredImagePanel = new CenteredImage(img);
JPanel wrapperPanel = new JPanel(new GridBagLayout());
wrapperPanel.add(centeredImagePanel);
JFrame frame = new JFrame("CenteredImage");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(800, 650));
// frame.getContentPane().setLayout(new GridBagLayout());
frame.getContentPane().add(wrapperPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}

Your core issue is (most likely) the fact that your panel doesn't provide any sizing hints to the layout manager, in order to allow it to make decisions about how much size it would need.
In order to achieve this, you need to override the getPreferredSize method of the panel to return the size you component would like to be.
This brings up a number of other issues:
Don't load images in paintComponent, this is time consuming and can make your UI appear as it's frozen. Also, paintComponent gets called a lot, so you should avoid anything in there which takes to time to perform
You should not reference src any where in you code. In this case, you will need use Class#getResource to obtain a reference to the image to load it
You should call super.paintComponent as a matter of course
For example
public class Panneau extends JPanel {
private BufferedImage img;
public Panneau() throws IOException {
img = ImageIO.read(getClass().getResource("/disantiammo/image/image.png"));
}
public void getPrefferedSize() {
return img == null ? new Dimension(0, 0) : new Dimension(img.getWidth(), img.getHeight());
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, this);
}
}
}
PS: I've not tried to center the image in the container, but if the layout manager is honoring the size of the component, it won't make a difference

Java repaint() doesn't call paintComponent() for drawing image

I have read a lot of answers about this problem but I can't manage to find my error even on a simple code. Here is the problem : I'd like to draw an Image in a JLabel which is in a JPanel, but the paintComponent() method of the JLabel isn't called.
Here is the code :
The ImagePainter class should draw an image
public class ImagePainter extends JLabel{
private Image image;
public ImagePainter(){
try {
image = ImageIO.read(new File("src/testgui/image.png"));
} catch (IOException exception) {
exception.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
System.out.println("in paintComponent");
}
}
Here is a standard JFrame. I took care to add the JPanel to the contentPane
public class Display extends JFrame{
public Display(){
JPanel jp = new JPanel();
ImagePainter i = new ImagePainter();
getContentPane().add(jp);
jp.add(i);
jp.repaint();
setSize(800, 800);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
And finally the main. I instanciate Display on the EDT like everyone tell to do :
public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable(){
#Override
public void run(){
Display d = new Display();
}
});
}
}
Finally, I observed that if I directly add the ImagePainter to the contentPane, the image is drawn correctly. It's probably a stupid error but I spend literally hours trying to find it and really can't see it. Thank you in advance !

The label does not account for the preferred size of the image when the image is custom painted! The panel by default has a flow layout. A flow layout does not stretch components to fit. So that label would have size of 0 x 0 pixels. You can confirm that by adding a visible border to the label.
But given the image is displayed in a label, why not just set the image as the icon of the label?

Also, the jp.repaint() statement in the Display constructor is useless, since you have not yet set the frame visible.

Issue with adding JLabel to JPanel

I'm looking to display an image on a JPanel, but when I run the code, the panel is blank. The method I'm attempting is a slightly modified version of this tutorial.
I've confirmed that all methods in the code are actually called using println. My frame and panel are visible, and I'm fairly certain I've added both the icon to the label, and the label to the panel. What am I missing?
The relevant parts of my code:
public class SYSTEM
public static void start() {
GameFrame GF = new GameFrame();
GamePanel GP = new GamePanel();
GF.add(GP);
GP.loadSprite("Player", new Dimension(0,0));
}
}
public class GameFrame extends JFrame {
public GameFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(SYSTEM.windowSize);
setVisible(true);
}
}
public class GamePanel extends JPanel {
ArrayList<Sprite> sprites = new ArrayList<Sprite>();
GamePanel() {
setVisible(true);
setSize(SYSTEM.windowSize);
setLayout(null);
}
public void loadSprite(String spriteName, Dimension pos) {
sprites.add(new Player());
add(sprites.get(0).getIcon());
}
public class Sprite {
protected JLabel icon;
protected BufferedImage image;
protected String filePath;
protected Dimension pos;
public JLabel getIcon() {
return icon;
}
}
public class Player extends Sprite {
public Player() {
filePath = "FILEPATH_OMITTED";
pos = new Dimension(0,0);
try {
image = ImageIO.read(new File(filePath));
} catch (IOException e) {
System.out.println(e);
}
icon = new JLabel(new ImageIcon(image));
}
}

Don't use components for games, you've thrown out the layout manager which is responsible for determining the size and location of the components, but you've failed to compensate for it. I'd recommend that you use a custom painting approach instead, see Painting in AWT and Swing and Performing Custom Painting for starters.
Just so I'm clear, you problem is directly related to setLayout(null); which is bad regardless of what you're doing

Image does not appear in JPanel using BufferedImage

I have a GUI with a created JPanel and a "Start" button. All I need is when I click "Start", an image will be loaded and appear on that JPanel.
But my problem is when I click "Start", nothing happens.
Can anyone help me fix this problem?
Here is my code:
private BufferedImage image;
public class ImagePanel extends JPanel {
public ImagePanel() {
try {
image = ImageIO.read(new File("C:\\Users\\HienTran\\Desktop\\Miranda-Kerr-16-240x320.jpg"));
} catch (IOException ex) {
// handle exception...
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
}
}
private void startBtnActionPerformed(java.awt.event.ActionEvent evt) {
stopBtn.setEnabled(true);
startBtn.setEnabled(false);
imageArea.add(new ImagePanel()); // imageArea is the JPanel in the GUI
}
When I replace 2 lines of imageArea by creating a new JFrame as below, that JFrame shows up with the image I added.
private void startBtnActionPerformed(java.awt.event.ActionEvent evt) {
stopBtn.setEnabled(true);
startBtn.setEnabled(false);
JFrame test = new JFrame("Window");
test.add(new ImagePanel());
test.setSize(image.getWidth(), image.getHeight() + 30);
test.setVisible(true);
}

When you add components to a visible GUI the basic code is:
panel.add(...);
panel.revalidate();
panel.repaint();
However, that probably won't help because by default a JPanel uses a FlowLayout and a FlowLayout respects the size of the component. Your ImagePanel will have a size of (0, 0) since you did not override the getPreferredSize() method.
There is no need to create a custom panel to paint your image. Just use a JLabel with an Icon then you let the label worry about the size. Don't reinvent the wheel.
I suggest you read the Swing tutorial for the basics. Maybe the section on How to Use Labels would be a good place to start. The tutorial will also show you a better way to design your class wo that you follow Swing guidelines.

First fix a bit:
try {
image = ImageIO.read(new File("C:\\Users\\HienTran\\Desktop\\Miranda-Kerr-16-240x320.jpg"));
} catch (IOException ex) {
ex.printStacktrace(); // see if there is an exception, like not finding or something
}
than:
If you add a panel, than need a layout refresh and a gui refresh:
imageArea.add(new ImagePanel());
imageArea.revalidate(); // refresh layout
imageArea.repaint(); // shedule painting

JFrame image display at frame resize

I have this JFrame containing a children of JPanel wherein it displays the image which is declared in this manner.
BufferedImage image = ImageIO.read(filename);
The program displays the image properly. But the only thing is, it requires to resize the frame to display the image.
Is there a possible way to display the image once the frame appears?

You should override paintComponent(Graphics g) and draw the image therein. In this case, you should do this for the JPanel component (I think? If not, do this for the JComponent(s) you're referring to). Also, since Swing is not thread-safe, ensure these modifications are performed in the EDT.
EXAMPLE
public class Demo{
private static BufferedImage bi;
public static void main(String[] args){
try{
loadImage();
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run(){
createAndShowGUI();
}
});
}
catch (IOException e){
// handle exception
}
}
private static void loadImage() throws IOException{
bi = ImageIO.read(new File("src/resource/braveheart.PNG"));
}
private static void createAndShowGUI(){
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel(){
#Override
protected void paintComponent(Graphics g){
Graphics g2 = g.create();
g2.drawImage(bi, 0, 0, getWidth(), getHeight(), null);
g2.dispose();
}
#Override
public Dimension getPreferredSize(){
return new Dimension(bi.getWidth(), bi.getHeight());
}
};
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
OUTPUT
It's important to keep in mind that this example ignores rendering hints, so when you maximize the JFrame, the image quality will be very poor. :)
EDIT
When answering this question, I assumed you had a basic understanding of Swing. I suppose I assumed too much. It is important to mention that all components should be added to the top-level container before it's been realized (i.e. made visible). This will ensure that everything is rendered without having to resize your frame. As others have suggested, you could have simply used a JLabel to render the image, and then added it to your JPanel. Instead, I promoted custom painting, which is perfectly acceptable, and to me, cleaner.

for dispaly Image or ImageIcon is better look for JLabel (basic stuff)