Develop Reference

Why is a Background Image of a JFrame only showing after i resize the window in Swing?

I have noticed some weird behaviour with setting an image as a background for my JFrames. I want to have a background image for both Frames display when they are created.
When i create Window1 inside my main method it only shows the background after i manually resize the window. When i click the button in Window1 and create window2 inside Window1, Window2 displays the background image correctly. When i create Window2 inside my main method the background image also does not show correctly.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class TestStart {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Window1();
}
});
}
}
public class Window1 extends JFrame {
Image img = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Tim\\Desktop\\water.jpg");
public Window1() {
super("gridtest");
setSize(600, 500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
this.setContentPane(new JPanel(){
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(img,0,0,getWidth(),getHeight(),null);
}
});
JButton btn = new JButton("klick");
add(btn, BorderLayout.CENTER);
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent actionEvent) {
new Window2();
}
});
pack();
setVisible(true);
}
}
public class Window2 extends JFrame {
Image img = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Tim\\Desktop\\water.jpg");
public Window2() {
super("gridsecond");
setSize(600, 500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
this.setContentPane(new JPanel(){
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(img,0,0,getWidth(),getHeight(),null);
}
});
pack();
setVisible(true);
}
}
I tried adding in revalidate()/repaint() calls and calling the paint method at different points in my code, but except for the weird behaviour i described above, i cant get the background image to show without resizing my window.
Disclaimer: I know it's not good practice to create a new JFrame for every window, but i am not able to change the whole project structure, so im stuck with this.

So, a series of issues that might be causing your issue...
First, using Toolkit.getDefaultToolkit().getImage
Image img = Toolkit.getDefaultToolkit().getImage("C:\\Users\\Tim\\Desktop\\water.jpg");
The problem with this is, the image loading is down on a seperate thread. This means that when getImage returns the image may or may not have actually been loaded
Second, when calling drawImage, you pass null as the ImageConsumer, so the component won't be notified of changes to the images "loaded" state and won't be able to schedule updates to the component accordingly...
this.setContentPane(new JPanel(){
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(img,0,0,getWidth(),getHeight(),null);
}
});
Three, this is more of a side effect, but, you've set the contentPane manually using a JPanel, which by default uses a FlowLayout, so using BorderLayout constraints is actually kind of pointless.
setLayout(new BorderLayout());
this.setContentPane(new JPanel(){
//...
JButton btn = new JButton("klick");
add(btn, BorderLayout.CENTER);
Besides, BorderLayout is the default layout manager used by window based components ;)
So, how would you fix this issue? Well, immediately, you could pass this as the ImageConsumer...
g.drawImage(img,0,0,getWidth(),getHeight(),this);
This will allow the component to monitor the loading state of the image and trigger repaints as required.
A longer term solution would be to stop using Toolkit.getDefaultToolkit().getImage (and by extension, ImageIcon), as they can be annoying, and start using ImageIO instead.
Apart from supporting a wider range of image formats, the API won't return till the image is fully loaded or an error occurred (try diagnose loading issues with the other APIs 🙄)
See Reading/Loading images for more details

Adding JComponents to JPanel and add the JPanel to JFrame is not working

I have a JFrame and I want to add a JPanel with a JButton. But all the guides in the internet seem to be wrong. If I follow these instructions my buttons will not be shown.
I know that there are questions similar to mine, but these posts have too much code instead of the problem in an isolated code. So I cannot figure out from it what their solution is.
public class MainClass {
public static void main (String[]args) {
Frame frame = new Frame();
}
}
public class Frame extends JFrame {
private JButton btn;
private JPanel pnl = new JPanel();
Frame () {
setSize(400,400);
setLayout(new FlowLayout());
setVisible(true);
setButtons();
add(pnl);
}
private void setButtons() {
btn = new JButton();
pnl.add(btn);
}
}

setVisible(true);
setButtons();
add(pnl);
Your components have a size of (0, 0) so there is nothing to paint.
The solution is to make the frame visible AFTER all the components have been added to the frame:
setButtons();
add(pnl);
setVisible(true);
When you make the frame visible, or use the pack(), method the layout manager is invoked so know the components will have a size/location.
but these posts have too much code instead of the problem in an isolated code.
I suggest you start with the code example from the Swing Tutorial for Swing basics. Download an example and use it as a starting point for a better structured class. For example all Swing components should be create on the Event Dispatch Thread (EDT).

Paint Method is not Called

After making an instance in a previous frame, I'm trying to the background image on the next frame but as a result, I just saw the debugged result and found out that the paint method was not called. From what I know, the paint method is inherited by the JFrame class and with this logic, I've made it overrided. As I guess, the reason happen the logical error is from what I used the event handler and made the instance in the EventHandlerClass.
if(e.getActionCommand().equals(ButtonTo))
if(idString.equals("USER"))
{
{
if("1234".equals(pwSt))
{
System.out.println("Wellcome");
if(gs==null)
{
gs=new GameStart();
}
}
else
{
System.out.println("Confirm your password");
}
}
}
This is a code that If an action is performed it will make an instance(gs). After doing this, I noticed that the instance has been used as to make a new console frame.
class GameStart extends JFrame {
private Image screenImage;
private Graphics screenGraphic;
private Image introBackgroundImage;
private ImageIcon img;
GameStart()
{
JFrame jf=new JFrame("Game Set");
jf.setBounds(300, 300, 400, 200);
jf.setLayout(new BorderLayout());
JButton bt1=new JButton("Start");
JButton bt2=new JButton("Exit");
JPanel panel1=new JPanel();
panel1.add(bt1);panel1.add(bt2);
setContentPane(panel1);
jf.add(panel1, BorderLayout.SOUTH);
bt1.addActionListener(new Choice());
bt2.addActionListener(new Choice());
jf.setVisible(true);
img=new ImageIcon("./Images/backGroundImage.jpg");
System.out.println("1");
}
public void paint(Graphics g) {
screenImage=createImage(200, 200);
screenGraphic=screenImage.getGraphics();
screenDraw(screenGraphic);
g.drawImage(screenImage, 0, 0, null);
System.out.println("2");
}
public void screenDraw(Graphics g)
{
this.repaint();
System.out.println("3");
}
Now, With making a frame and some buttons, I expect to show all the numbers(1, 2, 3) that indicate the result but Just did number 1.

There are some errors in your code that I can see at first glance:
You're extending JFrame, but you're not adding any extra functionality to it, see: Extends JFrame vs. creating it inside the program. Instead, build your GUI towards the use of JPanels and override their paintComponent(...) method and not the paint(...) one.
You're breaking the paint-chain: After doing the above point, in paintComponent(), call super.paintComponent(...)
Maybe there are others but I'm currently busy and can't test your code, but the ones above should help with your issue.

JPanel wont appear until being resized [duplicate]

I subclass JPanel to overwrite paintComponent(Graphics), I want to draw an image onto jpanel in a jframe.
But my image hasn't shown up until I make a change to jframe's size.
This is my code:
public class ImagePanel extends JPanel{
public void setImage(BufferedImage bi)
{
image = bi;
revalidate();
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if(image != null)
{
g.drawImage(image, 0, 0, this);
}
}
}

Verify that you invoke setVisible() after adding components and calling pack(), as discussed in this related example. You may also need to adopt an appropriate layout. Invoking repaint(), as suggested here, may fix the symptom but not the underlying cause.

Take a look at the docs for JPanel.add(), which it inherits from java.awt.Container:
Appends the specified component to the end of this container. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).
This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
Emphasis added.
Therefore, if you modify a Container after it's already been displayed, you must call validate() in order for it to show up. Just invoking repaint() is not enough. You may have noticed that calling setVisible(true) also works; this is because it calls validate() internally.

If you want to "refresh" the JPanel then you should call repaint(), which will call your paintComponent(). This should fix your problem:
public void setImage(BufferedImage bi)
{
image = bi;
EventQueue.invokeLater(new Runnable()
{
public void run()
{
repaint();
}
});
}
Its good practice to update and change the GUI using the EDT. Heres more info on the EDT if you're interested:
How does the event dispatch thread work?
repaint doesn't need to be called from the EDT. If you're changing the GUI, such as setting text to a JLabel, it should be inside of the EDT. Heres more information on what can be called outside of the EDT (courtesy of nIcE cOw):
Safe to use Component.repaint() outside EDT?

I had the same problem and fixed it by call setVisible(true); the JFrame I was using.
Example : if your JFrame does not update after using :
jframe.setContentPane(new MyContentPane());
fix it with :
jframe.setContentPane(new MyContentPane());
jframe.setVisible(true);
I know that it sounds silly to do this even though your JFrame is already visible, but that's the only way I've found so far to fix this problem (the solution proposed above didn't work for me).
Here is a complete example. Run it and then uncomment the "f.setVisible(true);" instructions in classes Panel1 and Panel2 and you'll see the difference. Don't forget the imports (Ctrl + Shift + O for automatic imports).
Main class :
public class Main {
private static JFrame f;
public static void main(String[] args) {
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(new Panel1(f));
f.pack();
f.setVisible(true);
}
}
Panel1 class :
public class Panel1 extends JPanel{
private JFrame f;
public Panel1(JFrame frame) {
f = frame;
this.setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS));
JButton b = new JButton("Panel 1");
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
f.setContentPane(new Panel2(f));
// Uncomment the instruction below to fix GUI "update-on-resize-only" problem
//f.setVisible(true);
}
});
add(b);
}
}
Panel2 class :
public class Panel2 extends JPanel{
private JFrame f;
public Panel2(JFrame frame) {
f = frame;
this.setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS));
JButton b = new JButton("Panel 2");
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
f.setContentPane(new Panel1(f));
// Uncomment the instruction below to fix GUI "update-on-resize-only" problem
//f.setVisible(true);
}
});
add(b);
}
}
Hope that helps.
Regards.

I also had same problem but I found a solution. Just create a jframe object on top and call jframe methods at the bottom like jf.pack(), jf.setVisible(), jf.setSize(), jf.setDefaultCloseOpetion() should be at the bottom of the all UIs added in that frame you will find it work great.

How can I refresh a JFrame with BufferedImage in it?

In addition to my question How can I more quickly render my array?, I made the following class to make a JFrame:
package myprojects;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
class BackgroundImageJFrame extends JFrame {
public BackgroundImageJFrame(BufferedImage img) {
setTitle("Background Color for JFrame");
int h = img.getHeight();
int w = img.getWidth();
setSize(w, h);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
setLayout(new BorderLayout());
setContentPane(new JLabel(new ImageIcon(img)));
setLayout(new FlowLayout());
// Just for refresh :) Not optional!
setSize(w-1, h-1);
setSize(w, h);
}
}
which I call with new BackgroundImageJFrame(img);. As I want to refresh the contents of this JFrame, this doesn't work optimally, since this creates a new JFrame everytime.
How could I alter this to just have the JFrame refreshed?

You can pretty simply do this by storing the JLabel control, and then setting the image with a method. Make sure you set the image on the Event Dispatch Thread!
I have revised the code to do this in a more stable way based on #MadProgrammer's excellent comments.
Brief summary of the issues addressed between this and the previous version:
You don't want the contentPane to be a JLabel, as it makes it more difficult to add other controls later and doesn't have a layout manager. I've added a JPanel in between, and given it BorderLayout.
The caller should be responsible for thread safety. I didn't do it this way originally because you didn't provide any calling code, but here, I do the Event Dispatch Thread delegation. Make sure you switch to the Event Dispatch Thread using EventQueue.invokeLater as I do here in main before calling setBackgroundImage().
I'm using setSize and setPreferredSize on the JLabel so that the layout managers can properly choose good sizes for the controls, and so that frame.pack works as expected.
I create the controls in the initComponents method, outside of the constructor, to make the code easier to follow and to make it easy to add more constructors later if necessary.
Here's the code:
public class NonogramSolutionJFrame extends JFrame {
private final JLabel label;
private final JPanel panel;
public NonogramSolutionJFrame(BufferedImage img) {
panel = new JPanel();
label = new JLabel();
initComponents(img);
}
private final void initComponents(BufferedImage img) {
setTitle("Background Color for JFrame");
setBackgroundImage(img);
setContentPane(panel);
panel.setLayout(new BorderLayout());
panel.add(label, BorderLayout.CENTER);
setLocationRelativeTo(null);
pack();
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void setBackgroundImage(final BufferedImage img) {
label.setIcon(new ImageIcon(img));
label.setPreferredSize(new Dimension(img.getWidth(), img.getHeight()));
}
public static void main(String... args) throws Exception {
BufferedImage img = ImageIO.read(NonogramSolutionJFrame.class.getResource("/nonogram.png"));
NonogramSolutionJFrame frame = new NonogramSolutionJFrame(img);
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
frame.setVisible(true);
}
});
}
}
Using the image from your other answer, this code produces the following (on Linux):