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JFrame Exit on close does not appear in java

Take the example from Oracle, there are some examples in your documentation.
My idea is the following:
I have achieved that my application has a transparent background, but the minimize and close application buttons do not appear
This is my code:
main
import javax.swing.JFrame;
import java.awt.*;
import javax.swing.*;
import static java.awt.GraphicsDevice.WindowTranslucency.*;
public class Textmovie extends JFrame {
/*
public Textmovie() {
//setLayout(new GridBagLayout());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
*/
public static void main(String[] args) {
JFrame jf = new JFrame("");
jf.setUndecorated(true);
jf.setBackground(new Color(0,0,0,10));
//jf.setOpacity(0.55f);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(new texscroll());
jf.setSize(720,480);
jf.setVisible(true);
}
}
Part 2
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
/**
*
* #author inide
*/
public class texscroll extends JPanel {
int x =510 , y = 25;
public texscroll() {
setOpaque(false);
}
#Override
public void paint(Graphics g){
super.paint(g);
Graphics2D g2 = (Graphics2D)g;
Font font = new Font("Arial",Font.BOLD + Font.PLAIN,15);
g2.setFont(font);
g2.setColor(Color.BLACK);
String string = "stackoverflow stackoverflow stackoverflow stackoverflow";
g2.drawString(string ,x,y);
try{Thread.sleep(14);}
catch(Exception ex)
{
};
x-=1;
if(x==-10*string.length()){
x= 510;
}
repaint();
// System.out.println(string.length() );
}
}
And this is shown when running in NetBeans IDE 8.0.2
They can explain to me what I have to do to make the buttons appear (minimize and close application).

If you actually dig into the code based on the exception:
Exception in thread "AWT-EventQueue-0" java.awt.IllegalComponentStateException: The frame is decorated
at java.desktop/java.awt.Frame.setBackground(Frame.java:989)
You'll find that it's impossible to make a frame transparent AND be decorated...
#Override
public void setBackground(Color bgColor) {
synchronized (getTreeLock()) {
if ((bgColor != null) && (bgColor.getAlpha() < 255) && !isUndecorated()) {
throw new IllegalComponentStateException("The frame is decorated");
}
super.setBackground(bgColor);
}
}
The fact that the tutorials show it working is irrelevant and an error on the part of the tutorials.
It "might" have been possible in earlier "unreleased" versions of the API (using AWTUtilities), but it simply no longer possible
Now, we've got that out the way, this, inside paint...
try {
Thread.sleep(14);
} catch (Exception ex) {
};
x -= 1;
if (x == -10 * string.length()) {
x = 510;
}
repaint();
is not how you do animation in Swing
This is just going to cause you no end of issues, as nothing is committed to the native peer until AFTER the paintComponent exist (this is how double buffering works)
See Concurrency in Swing for more details.
A more appropriate solution might look something like...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Textmovie extends JFrame {
public static void main(String[] args) {
new Textmovie();
}
public Textmovie() throws HeadlessException {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame jf = new JFrame("");
jf.setUndecorated(true);
jf.setBackground(new Color(0, 0, 0, 10));
//jf.setOpacity(0.55f);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.add(new texscroll());
jf.pack();
jf.setLocationRelativeTo(null);
jf.setVisible(true);
}
});
}
public static class texscroll extends JPanel {
private int x = 510, y = 25;
private String string = "stackoverflow stackoverflow stackoverflow stackoverflow";
public texscroll() {
Font font = new Font("Arial", Font.BOLD + Font.PLAIN, 15);
setFont(font);
setForeground(Color.BLACK);
setOpaque(false);
Timer timer = new Timer(14, new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
x -= 1;
if (x == -10 * string.length()) {
x = 510;
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(720, 480);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); //To change body of generated methods, choose Tools | Templates.
Graphics2D g2 = (Graphics2D) g;
g2.drawString(string, x, y);
}
}
}
See How to Use Swing Timers for more details

jf.setUndecorated(true);
makes the title bar invisible and that includes the minimize and close buttons so you should remove that line (because it's false by default)

It’s because you’re calling jf.setUndecorated(true). This method removes the the title bar, which contains the minimize and maximize buttons.
Unfortunately, the window have to be undecorated to have a system title bar, but the look and feel can provide a title bar. To enable it, you have to call this before your frame is made visible:
JFrame.setDefaultLookAndFeelDecorated(true);

Paint Component seems to be causing cursor and Mouse Listener of Label to not work

Using LayerUI to add labels to the upper corner of a tabbed pane. Would like to allow these labels to display as hyperlinks, so I set the color blue, the cursor to a hand and I added a mouselistener.
Howev,er when I paint the component the cursor customization and mouse listener are not not working.
sample image
Sample Application:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JLayer;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
import javax.swing.plaf.LayerUI;
public class TopRightCornerLabelLayerUITest {
public static JPanel makeUI() {
JPanel resultPanel = new JPanel();
resultPanel.setLayout( new BorderLayout());
resultPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.add("Tab 1", new JPanel());
tabbedPane.add("Tab 2", new JPanel());
resultPanel.add(new JLayer<JComponent>(tabbedPane, new TopRightCornerLabelLayerUI()), BorderLayout.CENTER);
return resultPanel;
}
private static void initandShow()
{
JDialog dialog = new JDialog();
dialog.getContentPane().add(makeUI());
dialog.setSize(520, 240);
dialog.setLocationRelativeTo(null);
dialog.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
initandShow();
}
});
}
}
class TopRightCornerLabelLayerUI extends LayerUI<JComponent> {
private JPanel rubberStamp = new JPanel();
#Override public void paint(Graphics g, JComponent c) {
super.paint(g, c);
JLabel layoutHyperlink = new JLabel("<html><a href=''>File Layout and Descriptions</a></html>");
JLabel templateHyperlink = new JLabel("<html><a href=''>Download Template</a></html>");
layoutHyperlink.setForeground(Color.BLUE.darker());
layoutHyperlink.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
layoutHyperlink.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// the user clicks on the label
System.err.println("clicked");
}
});
templateHyperlink.setForeground(Color.BLUE.darker());
templateHyperlink.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
templateHyperlink.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// the user clicks on the label
System.err.println("clicked");
}
});
// Add components
Dimension templateDimension = templateHyperlink.getPreferredSize();
int x = c.getWidth() - templateDimension.width - 5;
SwingUtilities.paintComponent(g, templateHyperlink, rubberStamp, x, 2, templateDimension.width , templateDimension.height);
Dimension layoutDimension = layoutHyperlink.getPreferredSize();
x = c.getWidth() - layoutDimension.width - 15 - templateDimension.width;
SwingUtilities.paintComponent(g, layoutHyperlink, rubberStamp, x, 2, layoutDimension.width, templateDimension.height);
}
}

I was actually unaware of class JLayer until I read your question. I don't have a complete answer but I think it's enough to give you a push in the right direction. I was helped by the lesson in Oracle's Java tutorial: How to Decorate Components with the JLayer Class. That lesson has a section entitled Responding to Events which helped me to figure out how to partially solve your issue. Basically you are just painting the labels and not actually adding them as components and therefore they will not respond to mouse events. Since the labels can be considered part of the JLayer component that is added as a component, you can configure that JLayer to respond to mouse events. As stated in the tutorial lesson, you need to override some other methods in your TopRightCornerLabelLayerUI class. The code below contains two of those methods. Add them to your code and see if they give you the expected result.
public void installUI(JComponent c) {
super.installUI(c);
((JLayer<?>) c).setLayerEventMask(AWTEvent.MOUSE_EVENT_MASK);
}
protected void processMouseEvent(MouseEvent e, JLayer l) {
if (e.getID() == MouseEvent.MOUSE_CLICKED) {
Point pt = e.getPoint();
if (pt.x >= xTemplateHyperlink && pt.x <= (xTemplateHyperlink + widthTemplateHyperlink)) {
System.out.println("clicked");
}
}
}
EDIT:
Forgot to mention that I added the following members to your TopRightCornerLabelLayerUI class...
private int xTemplateHyperlink;
private int yTemplateHyperlink;
private int widthTemplateHyperlink;
private int heightTemplateHyperlink;
And set their values in method paint() like so...
Dimension templateDimension = templateHyperlink.getPreferredSize();
xTemplateHyperlink = c.getWidth() - templateDimension.width - 5;
yTemplateHyperlink = 2;
widthTemplateHyperlink = templateDimension.width;
heightTemplateHyperlink = templateDimension.height;
which explains the code in method processMouseEvent().

Scale tiny low-resolution app to larger screen size

I am creating a retro arcade game in Java. The screen resolution for the game is 304 x 256, which I want to keep to preserve the retro characteristics of the game (visuals, animations, font blockiness, etc.).
But when I render this on a large desktop display, it is too small, as one would expect.
I'd like to be able to scale the window up say by a constant factor, without having to code the various paint(Graphics) methods to be knowledgeable about the fact that there's a scale-up. That is, I'd like the rendering code believe that the screen is 304 x 256. I also don't want to have to change my desktop resolution or go into full screen exclusive mode. Just want a big window with scaled up pixels, essentially.
I'd be looking for something along the following lines:
scale(myJFrame, 4);
and have all the contents automatically scale up.
UPDATE: Regarding input, my game happens to use keyboard input, so I don't myself need the inverse transform that trashgod describes. Still I can imagine that others would need that, so I think it's an appropriate suggestion.

One approach, suggested here, is to rely on drawImage() to scale an image of the content. Your game would render itself in the graphics context of a BufferedImage, rather than your implementation of paintComponent(). If the game includes mouse interaction, you'll have to scale the mouse coordinates as shown. In the variation below, I've given the CENTER panel a preferred size that is a multiple of SCALE = 8 and added the original as an icon in the WEST of a BorderLayout. As the default, CENTER, ignores a component's preferred size, you may want to add it to a (possibly nested) panel having FlowLayout. Resize the frame to see the effect.
f.setLayout(new FlowLayout());
f.add(new Grid(NAME));
//f.add(new JLabel(ICON), BorderLayout.WEST);
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
/**
* #see https://stackoverflow.com/a/44373975/230513
* #see http://stackoverflow.com/questions/2900801
*/
public class Grid extends JPanel implements MouseMotionListener {
private static final String NAME = "OptionPane.informationIcon";
private static final Icon ICON = UIManager.getIcon(NAME);
private static final int SCALE = 8;
private final BufferedImage image;
private int imgW, imgH, paneW, paneH;
public Grid(String name) {
super(true);
imgW = ICON.getIconWidth();
imgH = ICON.getIconHeight();
image = new BufferedImage(imgW, imgH, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = (Graphics2D) image.getGraphics();
ICON.paintIcon(null, g2d, 0, 0);
g2d.dispose();
this.addMouseMotionListener(this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(imgW * SCALE, imgH * SCALE);
}
#Override
protected void paintComponent(Graphics g) {
paneW = this.getWidth();
paneH = this.getHeight();
g.drawImage(image, 0, 0, paneW, paneH, null);
}
#Override
public void mouseMoved(MouseEvent e) {
Point p = e.getPoint();
int x = p.x * imgW / paneW;
int y = p.y * imgH / paneH;
int c = image.getRGB(x, y);
this.setToolTipText(x + "," + y + ": "
+ String.format("%08X", c));
}
#Override
public void mouseDragged(MouseEvent e) {
}
private static void create() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new Grid(NAME));
f.add(new JLabel(ICON), BorderLayout.WEST);
f.pack();
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
create();
}
});
}
}

One approach, suggested here, is to rely on the graphics context's scale() method and construct to an inverse transform to convert between mouse coordinates and image coordinates. In the example below, note how the original image is 256 x 256, while the displayed image is scaled by SCALE = 2.0. The mouse is hovering over the center the image; the tooltip shows an arbitrary point in the display and the center point (127, 127) in the original.
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
/** #see https://stackoverflow.com/a/2244285/230513 */
public class InverseTransform {
private static final double SCALE = 2.0;
public static void main(String[] args) {
JFrame frame = new JFrame("Inverse Test");
BufferedImage image = getImage(256, 'F');
AffineTransform at = new AffineTransform();
at.scale(SCALE, SCALE);
frame.add(new ImageView(image, at));
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
private static BufferedImage getImage(int size, char c) {
final Font font = new Font("Serif", Font.BOLD, size);
BufferedImage bi = new BufferedImage(
size, size, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = bi.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setPaint(Color.white);
g2d.fillRect(0, 0, size, size);
g2d.setPaint(Color.blue);
g2d.setFont(font);
FontMetrics fm = g2d.getFontMetrics();
int x = (size - fm.charWidth(c)) / 2;
int y = fm.getAscent() + fm.getDescent() / 4;
g2d.drawString(String.valueOf(c), x, y);
g2d.setPaint(Color.black);
g2d.drawLine(0, y, size, y);
g2d.drawLine(x, 0, x, size);
g2d.fillOval(x - 3, y - 3, 6, 6);
g2d.drawRect(0, 0, size - 1, size - 1);
g2d.dispose();
return bi;
}
private static class ImageView extends JPanel {
private BufferedImage image;
private AffineTransform at;
private AffineTransform inverse;
private Graphics2D canvas;
private Point oldPt = new Point();
private Point newPt;
#Override
public Dimension getPreferredSize() {
return new Dimension( // arbitrary multiple of SCALE
(int)(image.getWidth() * SCALE * 1.25),
(int)(image.getHeight() * SCALE * 1.25));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
try {
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
inverse = g2d.getTransform();
inverse.invert();
g2d.translate(this.getWidth() / 2, this.getHeight() / 2);
g2d.transform(at);
g2d.translate(-image.getWidth() / 2, -image.getHeight() / 2);
inverse.concatenate(g2d.getTransform());
g2d.drawImage(image, 0, 0, this);
} catch (NoninvertibleTransformException ex) {
ex.printStackTrace(System.err);
}
}
ImageView(final BufferedImage image, final AffineTransform at) {
this.setBackground(Color.lightGray);
this.image = image;
this.at = at;
this.canvas = image.createGraphics();
this.canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
this.canvas.setColor(Color.BLACK);
this.addMouseMotionListener(new MouseMotionAdapter() {
#Override
public void mouseMoved(MouseEvent e) {
Point m = e.getPoint();
Point i = e.getPoint();
try {
inverse.inverseTransform(m, i);
setToolTipText("<html>Mouse: " + m.x + "," + m.y
+ "<br>Inverse: " + i.x + "," + i.y + "</html>");
} catch (NoninvertibleTransformException ex) {
ex.printStackTrace();
}
}
});
}
}
}

Thanks to trashgod for pointing me in the right direction with his two answers. I was able to combine elements of both answers to arrive at something that works for what I need to do.
So first, my goal was to scale up an entire UI rather than scaling up a single icon or other simple component. By "an entire UI" I specifically mean a JPanel containing multiple custom child components laid out using a BorderLayout. There are no JButtons or any other interactive Swing components, and no mouse input (it's all keyboard-based input), so really I just need to scale a 304 x 256 JPanel up by a factor of 3 or 4.
Here's what I did:
package bb.view;
import javax.swing.JComponent;
import javax.swing.JPanel;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import static bb.BBConfig.SCREEN_WIDTH_PX; // 304
import static bb.BBConfig.SCREEN_HEIGHT_PX; // 256
public class Resizer extends JPanel {
private static final int K = 3;
private static final Dimension PREF_SIZE =
new Dimension(K * SCREEN_WIDTH_PX, K * SCREEN_HEIGHT_PX);
private static final AffineTransform SCALE_XFORM =
AffineTransform.getScaleInstance(K, K);
public Resizer(JComponent component) {
setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0));
add(component);
}
#Override
public Dimension getPreferredSize() {
return PREF_SIZE;
}
#Override
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setTransform(SCALE_XFORM);
super.paint(g2);
}
}
Some important elements of the solution:
Using a FlowLayout here shrinkwraps the child component, which is what I want. (Thanks trashgod for that.) That is, I don't want the child to expand to fill the Resizer preferred size, because that wrecks the child component's layout. Specifically it was creating this huge gap between the child component's CENTER and SOUTH regions.
I configured the FlowLayout with left alignment and hgap, vgap = 0. That way my scale transform would have the scaled up version anchored in the upper left corner too.
I used an AffineTransform to accomplish the scaling. (Again thanks trashgod.)
I used paint() instead of paintComponent() because the Resizer is simply a wrapper. I don't want to paint a border. I basically want to intercept the paint() call, inserting the scale transform and then letting the JPanel.paint() do whatever it would normally do.
I didn't end up needing to render anything in a separate BufferedImage.
The end result is that the UI is large, but the all the code other than this Resizer thinks the UI is 304 x 256.

How can I repaint only one layer of the JLayeredPane layers?

I am writing an application which has layers (I used JLayeredPane) containing two principal layers (JPanels). I override the paintComponent method of the Panel at the bottom (call it Map) so it paints a Map, and the the paintComponent method of the one at the top (call it selectionPanel) so it paints a selection of an element.
Here's a summary of the structure:
layers -
|-selectionPanel(on top)
|-Map (at bottom)
I want the Map to stay static, ie, not to do any repaint (except the initial one) since it does not change.
The trouble is, whenever I call selectionPanel.repaint(), Map gets repainted as well! This is a definitely not efficient.
I think this is due to the eager painting behavior of JLayeredPane. Is there a way to disable this feature in JLayeredPane?
In case you're interested to see the above effect, I've modified this example:
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
/** #see https://stackoverflow.com/q/9625495/230513 */
public class LayerDemo extends JFrame {
private static final Dimension d = new Dimension(320, 240);
public LayerDemo() {
JLayeredPane layers = new JLayeredPane();
layers.setPreferredSize(d);
layers.add(new LayerPanel(1 * d.height / 8), 100);
layers.add(new LayerPanel(2 * d.height / 8), 101);
layers.add(new LayerPanel(3 * d.height / 8), 102);
this.add(layers, BorderLayout.CENTER);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.pack();
this.setLocationByPlatform(true);
}
private static class LayerPanel extends JPanel {
private static final Random r = new Random();
private int n;
private Color color = new Color(r.nextInt());
public LayerPanel(int n) {
this.n = n;
this.setOpaque(false);
this.setBounds(n, n, d.width / 2, d.height / 2);
this.addMouseListener(new MouseHandler(this));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
color = new Color(r.nextInt());
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(color);
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, ((float) 20) / 100));
g2d.fillRoundRect(0, 0, getWidth(), getHeight(), 16, 16);
g2d.setColor(Color.black);
g2d.drawString(String.valueOf(n), 5, getHeight() - 5);
}
}
private static class MouseHandler extends MouseAdapter {
LayerPanel panel;
MouseHandler(LayerPanel panel) {
this.panel = panel;
}
#Override
public void mouseClicked(MouseEvent e) {
panel.repaint();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
(new LayerDemo()).setVisible(true);
}
});
}
}

Is there a way to disable this feature in JLayeredPane?
If is not a JLayeredPane feature. It is a Swing painting feature.
this.setOpaque(false);
When you make a component non-opaque, then Swing needs to repaint the parent component to make sure the background is painted properly.
In your case it looks like you are using transparency so you would definitely need the background to be repainted.
whenever I call selectionPanel.repaint(), Map gets repainted as well
If you are only painting a certain area of the child panel then you can use:
selectionPanel.repaint(Rectangle)
to minimize the area that is repainted.
color = new Color(r.nextInt());
Don't change the color in the paintComponent() method. This should be done in the MouseListener so it only affects the panel you click on. So even though the other panels will be repainted, their colors will not randomly change.

Painting issue with JLayer and JPanel

I want to paint an icon when user's input is invalid. I've found an example by Oracle and modified it for my purposes. The painting of Icon works correctly but when I change the value to correct the icon goes not completly invisible: the part which is drawn over the JPanel is still displayed.
Here is my code:
import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.text.NumberFormat;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayer;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.plaf.LayerUI;
public class FieldValidator extends JPanel {
private static final int ICON_SIZE = 12;
private static final Icon ICON = createResizedIcon((ImageIcon) UIManager.getIcon("OptionPane.errorIcon"));
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
createUI();
}
});
}
public static void createUI() {
final JFrame f = new JFrame ("FieldValidator");
final JComponent content = createContent();
f.add (content);
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo (null);
f.setVisible (true);
}
private static JComponent createContent() {
final LayerUI<JPanel> panelUI = new ValidationLayerUI();
// Number field.
final JLabel numberLabel = new JLabel("Number:");
final NumberFormat numberFormat = NumberFormat.getInstance();
final JFormattedTextField numberField = new JFormattedTextField(numberFormat) {
/**
* {#inheritDoc}
*/
#Override
public void replaceSelection(String content) {
super.replaceSelection(content);
getParent().repaint();
}
};
numberField.setColumns(16);
numberField.setFocusLostBehavior(JFormattedTextField.PERSIST);
numberField.setValue(42);
final int i = (ICON_SIZE / 2) + (ICON_SIZE % 2);
final JPanel numberPanel = new JPanel();
numberPanel.add(numberLabel);
final JPanel panel = new JPanel(new GridBagLayout());
final GridBagConstraints constr = new GridBagConstraints();
constr.insets = new Insets(i, i, i, i);
constr.weightx = 1;
constr.weighty = 1;
constr.fill = GridBagConstraints.BOTH;
panel.add(numberField, constr);
numberPanel.add(new JLayer<JPanel>(panel, panelUI));
return numberPanel;
}
//Icon resized to 12x12
private static Icon createResizedIcon(ImageIcon anIcon) {
final BufferedImage result = new BufferedImage(ICON_SIZE, ICON_SIZE, BufferedImage.TYPE_INT_ARGB);
final Graphics2D g = result.createGraphics();
g.setComposite(AlphaComposite.Src);
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
g.drawImage(anIcon.getImage(), 0, 0, ICON_SIZE, ICON_SIZE, null);
g.dispose();
return new ImageIcon(result);
}
static class ValidationLayerUI extends LayerUI<JPanel> {
#Override
public void paint (Graphics g, JComponent c) {
super.paint (g, c);
final JLayer jlayer = (JLayer) c;
final JPanel panel = (JPanel) jlayer.getView();
final JFormattedTextField ftf = (JFormattedTextField) panel.getComponent(0);
if (!ftf.isEditValid()) {
ICON.paintIcon(panel, g, 0, panel.getHeight() - ICON.getIconHeight());
}
}
}
}
Here is the screens:
Initial all is correct
When I paint invalid Icon all is still correct
But when the value goes correct only the text field will be repainted
How can I force the JPanel to repaint???
P.S. I've already found an approach with JLayeredPane which works correct, but I want to know what is wrong in my code?

How about using the DocumentListener:
numberField.getDocument().addDocumentListener(new DocumentListener() {
#Override public void insertUpdate(DocumentEvent e) {
//Container c = numberField.getParent();
Container c = SwingUtilities.getUnwrappedParent(numberField);
if (c != null) {
c.repaint();
}
}
#Override public void removeUpdate(DocumentEvent e) {
insertUpdate(e);
}
#Override public void changedUpdate(DocumentEvent e) {}
});
Edit
Quote from this link: Painting in AWT and Swing
The RepaintManager The purpose of Swing's RepaintManager class is to
maximize the efficiency of repaint processing on a Swing containment
hierarchy, and also to implement Swing's 'revalidation' mechanism (the
latter will be a subject for a separate article). It implements the
repaint mechanism by intercepting all repaint requests on Swing
components (so they are no longer processed by the AWT) and
maintaining its own state on what needs to be updated (known as "dirty
regions"). Finally, it uses invokeLater() to process the pending
requests on the event dispatching thread, as described in the section
on "Repaint Processing" (option B).
In this case the parent JPanel is not dirty region when isEditValid() status changed. so remaining previous Icon paint.