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Why doesn't the image paint over my JPanel?

I have been struggling with this for some time. At first, I only used ActionListener, then I added the paintComponent, but I have no idea what to put there. I read some tutorials and used their code as an example, but it still doesn't work. Right now, the end result is the same as it was without PaintComponent.
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Scream extends JPanel {
private JButton button = new JButton("OK");
private Color screenColor;
private JPanel panel = new JPanel();
private JFrame frame;
private Dimension screenSize;
private ImageIcon image;
private JLabel label = new JLabel(image);
private int x;
private int y;
private boolean mouseClicked;
public Scream() {
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e ) {
if (e.getSource() == button) {
mouseClicked = true;
frame.getContentPane().add(label);
frame.setSize(image.getIconWidth(), image.getIconHeight());
panel.repaint();
}
}
});
frame = new JFrame ("Existential angst");
screenColor = new Color(150, 100, 0);
panel.setBackground( screenColor );
frame.add(button, BorderLayout.PAGE_END);
frame.add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1300, 700);
frame.setVisible(true);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
image.paintComponent(this, g, 1300, 700);
}
public static void main (String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
Scream scream = new Scream();
}
});
}
}

If you are trying to dynamically add an image to a panel then you need to add the label to the panel. There is no need for any custom painting.
The basic code for adding components to a visible GUI is:
panel.add(...);
panel.revalidate();
panel.repaint();
Also, don't attempt to set the size of the frame to the size of the image. A frame contains a titlebar and borders. Instead you can use frame.pack();

I noticed a couple of issues:
image is never initialized to anything so it is null, effectively making the label empty. I assume maybe your example was just incomplete?
Once I initialized the image to something, your example still did not work. Turns out adding label without specifying any constraint basically does nothing (I assume since adding a component to a border layout without a constraint puts it in the center where panel already is). When I added the label to BorderLayout.NORTH, everything worked (though resizing the frame to the size of the image makes it only partially visible since the frame includes the OK button)

How make a jfram resize slowly [duplicate]

I'm trying to resize a window dynamically using a Timer object, but not succeeding... I set the preferred size of the panel in the constructor, which sets the size of the window nicely, though only once. The preferred size changes after the program is initialized, but the window size stays the same. Why? Because the constructor is initialized only once and therefore isn't affected by the size change? If so, how could I get around this to resize the window in real-time?
I know this won't solve the problem in the exercise given in the beginning comments, so please ignore that :-)
/*
* Exercise 18.15
*
* "(Enlarge and shrink an image) Write an applet that will display a sequence of
* image files in different sizes. Initially, the viewing area for this image has
* a width of 300 and a height of 300. Your program should continuously shrink the
* viewing area by 1 in width and 1 in height until it reaches a width of 50 and
* a height of 50. At that point, the viewing area should continuously enlarge by
* 1 in width and 1 in height until it reaches a width of 300 and a height of 300.
* The viewing area should shrink and enlarge (alternately) to create animation
* for the single image."
*
* Created: 2014.01.07
*/
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Ex_18_15 extends JApplet {
// Main method
public static void main(String[] args) {
JFrame frame = new JFrame();
Ex_18_15 applet = new Ex_18_15();
applet.isStandalone = true;
frame.add(applet);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
// Data fields
private boolean isStandalone = false;
private Image image = new ImageIcon("greenguy.png").getImage();
private int xCoordinate = 360;
private int yCoordinate = 300;
private Timer timer = new Timer(20, new TimerListener());
private DrawPanel panel = new DrawPanel();
// Constructor
public Ex_18_15() {
panel.setPreferredSize(new Dimension(xCoordinate, yCoordinate));
add(panel);
timer.start();
}
class DrawPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this);
}
}
class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if(yCoordinate <= 50) {
yCoordinate++;
xCoordinate++;
}
else if(yCoordinate >= 300) {
yCoordinate--;
xCoordinate--;
}
panel.setPreferredSize(new Dimension(xCoordinate, yCoordinate));
repaint();
}
}
}

You need to re-pack your JFrame to resize it. For instance at the end of your ActionListener:
Window win = SwingUtilities.getWindowAncestor(panel);
win.pack();
A question for you though: Why in heaven's name is your class extending JApplet and not JPanel? Or if it needs to be an applet, why are you stuffing it into a JFrame?
Edit
Regarding your comment:
Wouldn't it usually be extending JFrame not JPanel? I'm stuffing it into a JFrame to allow it to run as an application as well as an applet. That's how 'Introduction to Java Programming' tells me how to do it :p Adding your code at the end of the actionPerformed method didn't do anything for me ;o
Most of your GUI code should be geared towards creating JPanels, not JFrames or JApplets. You can then place your JPanels where needed and desired without difficulty. Your book has serious issues and should not be trusted if it is telling you this.
Edit 2
Works for me:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
#SuppressWarnings("serial")
public class ShrinkingGui extends JPanel {
private static final int INIT_W = 400;
private static final int INIT_H = INIT_W;
private static final int TIMER_DELAY = 20;
private int prefW = INIT_W;
private int prefH = INIT_H;
public ShrinkingGui() {
new Timer(TIMER_DELAY, new TimerListener()).start();;
}
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
private class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (prefW > 0 && prefH > 0) {
prefW--;
prefH--;
Window win = SwingUtilities.getWindowAncestor(ShrinkingGui.this);
win.pack();
} else {
((Timer)e.getSource()).stop();
}
}
}
private static void createAndShowGUI() {
ShrinkingGui paintEg = new ShrinkingGui();
JFrame frame = new JFrame("Shrinking Gui");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(paintEg);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

Java GUI - How to center a single button

I'm very new to java (I'm used to python).
NOTE: I do want the position to stay in the center even when the gui is resized.
I was wondering how I can center a single button? At the moment, the button is at the top of the gui.
public class main_gui extends JFrame{
public static void main(String[] args) {
// Initial window
JFrame start_frame = new JFrame("P.D");
start_frame.setSize(1200, 800);
start_frame.setVisible(true);
start_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Panel to hold our buttons
JPanel start_panel = new JPanel();
start_frame.add(start_panel);
// Button to initialize everything
JButton start_button = new JButton("Start");
// Take out the border around the text
start_button.setFocusable(false);
start_panel.add(start_button);
}
}
Here is what is currently looks like, I just want this button down a bit, to the center.

There is no need for the panel. Just add the button directly to the frame.
The easiest way is to use a GridBagLayout:
frame.setLayout( new GridBagLayout() );
frame.add(startButton, new GridBagConstraints());
By default the component will be centered horizontally and vertically within the GridBagLayout.

A quick solution would be to set the vertical gap between components of your FlowLayout to half the size of your JFrame:
public class MainGUI {
static java.awt.Dimension bd;
public static void main(String[] args) {
// Initial window
JFrame start_frame = new JFrame("P.D");
start_frame.setSize(1200, 800);
start_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Button to initialize everything
JButton start_button = new JButton("Start");
bd = start_button.getPreferredSize();
// Take out the border around the text
start_button.setFocusable(false);
// Panel to hold our buttons
java.awt.Dimension d = start_frame.getSize();
JPanel start_panel = new JPanel(new java.awt.FlowLayout(FlowLayout.CENTER, 0, d.height / 2 - bd.height / 2));
start_panel.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent evt) {
JPanel c = (JPanel) evt.getSource();
c.setLayout(new java.awt.FlowLayout(FlowLayout.CENTER, 0, c.getSize().height / 2 - bd.height / 2));
}
});
start_panel.add(start_button);
start_frame.add(start_panel);
start_frame.setVisible(true);
}
}
When the size of your JFrame is changed, the ComponentAdapter recalculates the new height and places the button to the new center.
In order to place the button to the vertical center, we calculate the height of your button and subtract its half from the vertical gap.
The horizontal center is automatically applied by the layout.
Your class should not extend JFrame if you instantiate another JFrame inside it and use it.
Class names should be nouns, in mixed case with the first letter of each internal word capitalized.
It is recommended to make your JFrame visible after you have added all widgets to it.
In order to use the SwingUtilities invoker and make your application code cleaner, let your class extend JFrame, write a constructor and call it this way:
public class MainGUIJFrame extends JFrame {
public MainGUIJFrame() {
initComponents();
}
private void initComponents() {
setTitle("P.D");
setSize(1200, 800);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
start_button = new JButton("Start");
bd = start_button.getPreferredSize();
// Take out the border around the text
start_button.setFocusable(false);
java.awt.Dimension d = getSize();
start_panel = new JPanel(new java.awt.FlowLayout(FlowLayout.CENTER, 0, d.height / 2 - bd.height / 2));
start_panel.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent evt) {
JPanel c = (JPanel) evt.getSource();
c.setLayout(new java.awt.FlowLayout(FlowLayout.CENTER, 0, c.getSize().height / 2 - bd.height / 2));
}
});
start_panel.add(start_button);
add(start_panel);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new MainGUIJFrame().setVisible(true);
}
});
}
private JButton start_button;
private JPanel start_panel;
private java.awt.Dimension bd;
}
You keep main simple and small this way, and bd does not have to be static anymore.

You can use a layout manager like BorderLayout if you want to put the button in the center so that it occupies the whole space in the frame. So, your code will look something like this:
public class main_gui extends JFrame{
public static void main(String[] args) {
// Initial window
JFrame start_frame = new JFrame("P.D");
start_frame.setSize(1200, 800);
start_frame.setVisible(true);
start_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Panel to hold our buttons
JPanel start_panel = new JPanel();
start_panel.setLayout(new BorderLayout());
start_frame.add(start_panel);
// Button to initialize everything
JButton start_button = new JButton("Start");
// Take out the border around the text
start_button.setFocusable(false);
start_panel.add(start_button, BorderLayout.CENTER);
}
}
You may go without using a layout manager. It's a bad practice but it should work. This code will put a small button in the center of the frame:
public class MainGUI {
public static void main(String[] args) {
JFrame start_frame = new JFrame("P.D");
int width = 1200;
int height = 800;
start_frame.setSize(width, height);
start_frame.setVisible(true);
start_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Panel to hold our buttons
JPanel start_panel = new JPanel();
start_panel.setLayout(null);
start_frame.add(start_panel);
// Button to initialize everything
JButton start_button = new JButton("Start");
buttonWidth = 80;
buttonHeight = 20;
start_button.setBounds(new Rectangle((width - buttonWidth)/2, (height - buttonHeight)/2, buttonWidth, buttonHeight));
start_button.setSize(new Dimension(buttonWidth, buttonHeight));
start_button.setFocusable(false);
start_panel.add(start_button);
}
}

The best way to do it is to use a Layout of your choice and try to make it work using that.
However, if you are sure your window won't be getting resized, or you're happy to deal with such events yourself, you could attempt working without a layout and position the button manually, e.g.:
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.Dimension;
public class main_gui {
public static void main(String[] args) {
// Initial window
JFrame start_frame = new JFrame("P.D");
int FrameWidth = 1200, FrameHeight = 800;
start_frame.setSize(FrameWidth, FrameHeight);
start_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Panel to hold our buttons
JPanel start_panel = new JPanel();
start_panel.setLayout(null); // Now working without a layout manager
// i.e, can position things manually.
start_frame.add(start_panel);
// Button to initialize everything
JButton start_button = new JButton("Start");
start_button.setFocusable(false); // Take out the border around the text
Dimension size = start_button.getPreferredSize();
start_button.setBounds( FrameWidth/2 - size.width/2,
FrameHeight/2 - size.height/2,
size.width, size.height);
start_panel.add(start_button);
// Display the Layout after all components have been added.
// (adding components after the frame has been set to visible
// may result in components not showing up reliably!)
start_frame.setVisible(true);
}
}

how to put my background image at the bottom

I want to put my background image at the very bottom in this frame, and the button on top. However the code I wrote below doesn't work. Can anyone see where the problems are?
Another thing is that even though I set the location for my button, it keep showing at the top center on the frame.
Please ignore the comment lines. (I was just guessing, and hoping them will work, but they don't apparently.)
public class Menu extends JFrame{
private JLayeredPane pane;
private JLayeredPane pane2;
public Menu(){
final JFrame f = new JFrame("Chinese Chess");
JButton play = new JButton("Play vs. AI");
f.setLayout(new FlowLayout());
f.setLocationRelativeTo(null);
f.setSize(800, 800);
f.setVisible(true);
f.setResizable(false);
//f.pack();
pane = new JLayeredPane();
pane2 = new JLayeredPane();
f.add(pane);
f.add(pane2);
//background image
JLabel background = new JLabel(new ImageIcon("res/img/background.png"));
background.setLocation(0, 0);
background.setSize(800, 800);
pane.add(background, JLayeredPane.FRAME_CONTENT_LAYER);
pane2.add(play, JLayeredPane.DEFAULT_LAYER);
//pane.moveToBack();
//button PlayAI
play.setLocation(500,500);
play.setPreferredSize(new Dimension(100,50));
//f.setLayout(new FlowLayout());
//frame menu
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//f.getContentPane().add(play);
play.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
new PlayAI();
}
});
}
public static void main(String[] args){
new Menu();
}

Problems/Solutions:
setLocation(...) and setBounds(...) types of calls are ignored by most layout managers. The only way to use them is to set the layout of the container to null via .setLayout(null);
But having said that, while null layouts and setBounds() might seem to Swing newbies like the easiest and best way to create complex GUI's, the more Swing GUI'S you create the more serious difficulties you will run into when using them. They won't resize your components when the GUI resizes, they are a royal witch to enhance or maintain, they fail completely when placed in scrollpanes, they look gawd-awful when viewed on all platforms or screen resolutions that are different from the original one.
So in sum -- don't do this, don't use null layouts or setBounds, but rather nest JPanels, each using its own layout manager, and thereby create easy to maintain and decent GUI's.
If you want an image to be in the background, then draw it in a JPanel that you use as a container for your GUI components by drawing it in the JPanel's paintComponent(Graphics g) method as has been demonstrated in many many similar questions on this site -- I'll find you some of mine in a second.
If you add any JPanels on top of this image drawing JPanel, be sure that you can see through them by calling setOpaque(false) on these overlying JPanels. Otherwise you'll cover up the image.
Your code has two JFrames when only one is needed. Get rid of the one you don't use.
You call setVisible(true) too early on the JFrame, before components have been added to the GUI -- don't. Call it only after adding everything to the GUI so all display OK.
You're creating two JLayedPanes, and completely covering one by the other by adding them to the JFrame without understanding how the JFrame's BorderLayout handles added components.
I suggest that you not even use one JLayeredPane but instead draw in the JPanel as noted above, and use that as your container.
Your code looks to be opening a completely new GUI window when the play button is pressed, and if so, this can get annoying to the user fast. Consider swapping views instead with a CardLayout.
For example:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
// extend JPanel so you can draw to its background
#SuppressWarnings("serial")
public class Menu2 extends JPanel {
private BufferedImage bgImage = null; // our background image
private JButton playButton = new JButton(new PlayVsAiAction("Play Vs. AI", KeyEvent.VK_P));
public Menu2(BufferedImage bgImage) {
this.bgImage = bgImage;
setLayout(new GridBagLayout()); // center our button
add(playButton);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (bgImage != null) {
g.drawImage(bgImage, 0, 0, this);
}
}
// to size our GUI to match a constant or the image.
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
// if you want to size it based on the image
if (bgImage != null) {
int width = bgImage.getWidth();
int height = bgImage.getHeight();
return new Dimension(width, height);
} else {
return super.getPreferredSize();
}
// if you want to size the GUI with constants:
// return new Dimension(PREF_W, PREF_H);
}
private class PlayVsAiAction extends AbstractAction {
public PlayVsAiAction(String name, int mnemonic) {
super(name); // have our button display this name
putValue(MNEMONIC_KEY, mnemonic); // alt-key to press button
}
#Override
public void actionPerformed(ActionEvent e) {
// TODO code to start program
}
}
private static void createAndShowGui() {
BufferedImage img = null;
String imagePath = "res/img/background.png";
try {
// TODO: fix this -- use class resources to get image, not File
img = ImageIO.read(new File(imagePath));
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
Menu2 mainPanel = new Menu2(img);
JFrame frame = new JFrame("Chinese Chess");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
createAndShowGui();
});
}
}

Apart from the solution above... you should create and launch your swing application this way:
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
// Instantiate your JFrame and show it
}

Thread sleep inside of actionPerformed method

First of all I want to say I'm aware this aproach is wrong so I'm asking this question because of pure curiousity. Lets say I have a swing application like this:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ThreadSleeping {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JButton button = new JButton("Load");
JLabel label = new JLabel();
public ThreadSleeping() {
panel.add(button);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
label.setIcon(new ImageIcon(
"C:/Users/Public/Pictures/Sample Pictures/Tulips.jpg"));
System.out.println("Tulips painted");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
label.setIcon(new ImageIcon(
"C:/Users/Public/Pictures/Sample Pictures/Koala.jpg"));
System.out.println("Koala painted");
}
});
frame.add(panel, BorderLayout.NORTH);
frame.add(label, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setSize(1024, 768);
// frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new ThreadSleeping();
}
});
}
}
Basically when I click a Load button I expect that Tulips.jpg image displays then GUI freezes for a 2 seconds and after that I expect that Koala.jpg image displays. But what happens is that: I click on button, GUI freezes for a 2 seconds and Koala.jpg displays. No Tulips.jpg before that. But thing that confuses me is when I put those System.out.println("Tulips painted"); and System.out.println("Koala painted");. So when I click on button it prints "Tulips painted" and after 2 seconds "Koala painted". Can someone tell me whats going on here? Regards.

works in this case, because you programatically freeze ouf Swing GUI, but there is/aren't another update(s), ot another JComponent(s)
doens't works in the case that there are a few another updated to the Swing GUI, Thread.sleep(int) freeze Event Dispatch Thread,
by default all updates to the JComponents XxxModels never will be visible on the JComponents view
example until sleep ended you'll lost all updated to the GUI

The point I intended to make in my comment:
if you sleep the edt, the resulting mis-behaviour is basically unpredictable.
Unpredictable in the sense that you can't know what will happen or not. All we can do, is guess ...
The technical reason is that most ui updates don't happen immediately but are scheduled: we can't really know what's waiting in the line behind us. Remember: it's only one lane, and when in the actionPerformed, it's we that are sitting in it.
For educational reasons, the code below is the original code with a couple of lines to un/comment to demonstrate different scenarios.
[0] resetting the icon before/after sleeping: as you already noticed, the first doesn't show even though the property is taken. Technical reason: visual update happens via label.repaint() which is scheduled on the EDT for latter processing (as its api doc states)
[1] skimming the api doc, we notice another method: paintImmediately(...) which is documented to do exactly what it's name says and allowed - as we are on the EDT - is allowed to be called. Looks like success, the yellow icon shows up.
[2] but wait: being in the center of a Borderline, the label fills that area anyway, independent of whether or not it has an icon. Let's try to put it into a region that requires a re-layout, as f.i. into the south. Back to square [0], yellow icon not showing.
[3] looking into the source of setIcon(..) reveals that layout is ... scheduled again. We learned in square [1] that we can force thingies to happen immediately, in case of layout that would be the pair invalidate() / validate(). Bingo, yellow icon even when in south.
[4] nasty subclass which schedules the icon property setting (note: while contrived here there is nothing in its contract that hinders subclasses to do it!). As the property isn't even set, yellow isn't showing, back to square [0]
At the end of the day (but before going to sleep the EDT :-), there is simply no way to reliably predict the visual outcome during the sleep. And visuals are only the tip of the ice...
/**
* Unpredictable behaviour when sleeping the EDT.
* http://stackoverflow.com/q/15600203/203657
*
* [0] run as-is: property set but yellow not showing
* [1] uncomment paintImmediately: yellow showing in center
* [2] add label to south: yellow not showing
* [3] force immediate in-/validation: yellow showing in south
* [4] subclass label with invoked property setting:
* property not set, yellow not showing
*
*/
public class ThreadSleeping {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JButton button = new JButton("Load");
JLabel label = new JLabel() {
// [4] subclass implemented to schedule the property setting
// #Override
// public void setIcon(final Icon icon) {
// SwingUtilities.invokeLater(new Runnable() {
// public void run() {
// superSetIcon(icon);
//
// }
// });
// }
//
// protected void superSetIcon(Icon icon) {
// super.setIcon(icon);
// }
//
};
public ThreadSleeping() {
panel.add(button);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
Icon firstIcon = new FixedIcon(Color.YELLOW, 100, 100);
Icon secondIcon = new FixedIcon(Color.RED, 500, 500);
label.setIcon(firstIcon);
// check if the property is already set
System.out.println(label.getIcon());
// following lines try to force the output before going to sleep
// [3] paintImmediately + force immediate re-layout
// label.invalidate();
// label.getParent().validate();
// {1] paintImmediately (fine for center, no effect for south)
// ((JComponent) label.getParent()).paintImmediately(0, 0, 5000, 5000);
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
label.setIcon(secondIcon);
}
});
frame.add(panel, BorderLayout.NORTH);
// un/comment one of the following, placing the
// label either in CENTER (= sized to fill)
frame.add(label, BorderLayout.CENTER);
// [2] or in SOUTH (= sized to pref)
// frame.add(label, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setSize(1024, 768);
frame.setVisible(true);
}
/**
* Simple fixed size Icon filling its area.
*/
public static class FixedIcon implements Icon {
private Color background;
private int width;
private int height;
public FixedIcon(Color background, int width, int height) {
this.background = background;
this.width = width;
this.height = height;
}
#Override
public void paintIcon(Component c, Graphics g, int x, int y) {
g.setColor(background);
g.fillRect(0, 0, width, height);
}
#Override
public int getIconWidth() {
return width;
}
#Override
public int getIconHeight() {
return height;
}
#Override
public String toString() {
return "[" + background + " w/h " + width + "/" + height + "]";
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new ThreadSleeping();
}
});
}
}