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Can't get absolute JLabel location

My JFrame uses a BorderLayout and it has a JLabel nested in several panels with different layout managers. I've tried several methods, however, cannot get the true position of where it sits in the frame.
I made a test UI and it seems like when other components are added the getX and getY parameters do not update. Other methods like getLocation do not provide a correct result either. Is there any way to obtain the exact location without manually calculating every possible offset from each component.
I am tracking the stated positions of the label (content) using a similar sized panel called content2 in the glass pane which I want to sit underneath content perfectly.
public class test {
private Dimension pSize = new Dimension(100,100);
private JFrame frame = new JFrame();
public static void main(String[] args) {
new test();
}
public test() {
//setup frame basics
frame.setPreferredSize(new Dimension(500,500));
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// setup GUI
JMenuBar j = new JMenuBar();
JMenuItem a = new JMenuItem("lol");
j.add(a);
JPanel j2 = new JPanel();
//setup main panel
JPanel main = new JPanel();
main.setBackground(Color.DARK_GRAY);
//setup side panel
FlowLayout f1 = new FlowLayout(FlowLayout.LEADING);
f1.setHgap(10);
f1.setVgap(0);
JPanel side = new JPanel();
side.setLayout(new BorderLayout());
side.setBackground(Color.gray);
side.setPreferredSize(new Dimension(150,100));
//setup JLabel (the main focus)
JLabel content = new JLabel("a");
content.setOpaque(true);
content.setBackground(Color.blue);
content.setPreferredSize(pSize);
// Setup the internal panels of side
JPanel top = new JPanel();//The panel where CONTENT is, the main focus
JPanel bot = new JPanel();
top.setBackground(Color.WHITE);
bot.setBackground(Color.orange);
top.setLayout(f1);
top.add(content);
side.add(top, BorderLayout.NORTH);
side.add(bot, BorderLayout.CENTER);
frame.add(main, BorderLayout.CENTER);
frame.add(side, BorderLayout.WEST);
frame.add(j2, BorderLayout.NORTH);
frame.setJMenuBar(j);
frame.pack();
frame.setVisible(true);
//Setting up the glass panel
JPanel pane = new JPanel();
pane.setLayout(null);
pane.setOpaque(false);
JPanel content2 = new JPanel();
content2.setBackground(Color.red);
content.revalidate();
int x = content.getX();
int y = content.getY();
// y = (int) content.getLocation().getY(); //returns a completely wrong location
//y = (int) content.getLocationOnScreen(); //returns a completely wrong location
/*
Point p = new Point();
p.setLocation(x, y);
p = SwingUtilities.convertPoint(content2, x, y, frame);
//SwingUtilities.convertPoint(content, p, frame);
y = (int) p.getY();
*
* Tried multiple SwingUtility converions to no avail
*
*/
// y = y +j.getHeight() + j2.getHeight(); // Manually calculating the Y off set works successfully but is too tedious for large project
y = y + content.getHeight();
content2.setBounds(x,y,100,100);
pane.add(content2);
frame.setGlassPane(pane);
frame.getGlassPane().setVisible(true);
frame.pack();
}
}
//frame.getContentPane().add(content);
//frame.add(content);
frame.setPreferredSize(new Dimension(500,500));
content.setBorder(BorderFactory.createEmptyBorder());
side.setLayout(new BorderLayout());
JPanel top = new JPanel();
JPanel bot = new JPanel();
top.setBackground(Color.WHITE);
bot.setBackground(Color.orange);
side.add(top, BorderLayout.NORTH);
top.setLayout(f1);
top.add(content);
side.add(bot, BorderLayout.CENTER);
frame.add(main, BorderLayout.CENTER);
frame.add(j2, BorderLayout.NORTH);
frame.add(side, BorderLayout.WEST);
frame.pack();
frame.setVisible(true);
JPanel pane = new JPanel();
pane.setLayout(null);
pane.setOpaque(false);
JPanel content2 = new JPanel();
content2.setBackground(Color.red);
content.revalidate();
int x = content.getX();
int y = content.getY();
// y = y +j.getHeight() + j2.getHeight();
y = y + content.getHeight();
content2.setBounds(x,y,100,100);
pane.add(content2);
frame.setGlassPane(pane);
frame.getGlassPane().setVisible(true);
frame.pack();
}
}

Conceptually you could make use of SwingUtilities.convertPoint or SwingUtilities.convertRectangle to convert between container contexts, for example...
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.border.EmptyBorder;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
GlassPane glassPane = new GlassPane();
JFrame frame = new JFrame();
frame.setGlassPane(glassPane);
frame.add(new MainPane(glassPane));
glassPane.setVisible(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public interface Tracker {
public void addTrackable(Trackable trackable);
public void removeTrackable(Trackable trackable);
}
public interface Trackable {
public JComponent[] getTrackedComponents();
}
public class MainPane extends JPanel {
private JLabel label = new JLabel("Catch me if you can");
public MainPane(Tracker tracker) {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(32, 32, 32, 32));
add(label);
tracker.addTrackable(new Trackable() {
#Override
public JComponent[] getTrackedComponents() {
return new JComponent[] { label };
}
});
}
}
public class GlassPane extends JPanel implements Tracker {
private List<Trackable> trackables = new ArrayList<>(8);
public GlassPane() {
setOpaque(false);
}
#Override
public void addTrackable(Trackable trackable) {
trackables.add(trackable);
revalidate();
repaint();
}
#Override
public void removeTrackable(Trackable trackable) {
trackables.remove(trackable);
revalidate();
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
for (Trackable trackable : trackables) {
for (JComponent component : trackable.getTrackedComponents()) {
Rectangle relativeBounds = SwingUtilities.convertRectangle(component.getParent(), component.getBounds(), this);
g2d.draw(relativeBounds);
}
}
g2d.dispose();
}
}
}
Well, that's pretty boring, it's one component inside one container, let's trying something a little more complicated...
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
GlassPane glassPane = new GlassPane();
JFrame frame = new JFrame();
frame.setLayout(new GridLayout(2, 2, 8, 8));
frame.add(new MainPane(glassPane));
frame.add(new MainPane(glassPane));
frame.add(new MainPane(glassPane));
frame.add(new MainPane(glassPane));
frame.setGlassPane(glassPane);
glassPane.setVisible(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public interface Tracker {
public void addTrackable(Trackable trackable);
public void removeTrackable(Trackable trackable);
}
public interface Trackable {
public JComponent[] getTrackedComponents();
}
public class MainPane extends JPanel {
private JLabel label = new JLabel("Catch me if you can");
public MainPane(Tracker tracker) {
setLayout(new GridBagLayout());
setBorder(new CompoundBorder(new LineBorder(Color.DARK_GRAY, 1, true), new EmptyBorder(32, 32, 32, 32)));
add(label);
tracker.addTrackable(new Trackable() {
#Override
public JComponent[] getTrackedComponents() {
return new JComponent[]{label};
}
});
}
}
public class GlassPane extends JPanel implements Tracker {
private List<Trackable> trackables = new ArrayList<>(8);
private List<Color> masterColors = new ArrayList<>(Arrays.asList(new Color[]{
Color.RED,
Color.GREEN,
Color.BLUE,
Color.CYAN,
Color.DARK_GRAY,
Color.GRAY,
Color.MAGENTA,
Color.ORANGE,
Color.PINK,
Color.YELLOW,}));
public GlassPane() {
setOpaque(false);
}
#Override
public void addTrackable(Trackable trackable) {
trackables.add(trackable);
revalidate();
repaint();
}
#Override
public void removeTrackable(Trackable trackable) {
trackables.remove(trackable);
revalidate();
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
List<Color> colors = new ArrayList<>(masterColors);
for (Trackable trackable : trackables) {
for (JComponent component : trackable.getTrackedComponents()) {
if (colors.isEmpty()) {
colors = new ArrayList<>(masterColors);
}
g2d.setColor(colors.remove(0));
Rectangle relativeBounds = SwingUtilities.convertRectangle(component.getParent(), component.getBounds(), this);
g2d.draw(relativeBounds);
}
}
g2d.dispose();
}
}
}
Here is a new smipler example program, trying to keep as close to your code as possible, that uses the convertRectangle but I can't manage to run it correctly
int y = (int) (r.getY() + r.getHeight()); ... are you deliberately trying to offset the "overlay"? This seems weird to me.
Another issue is, how does the GlassPane know when the child has changed position/size
So, I modified your code, getting rid of the "modification" to the x/y position (so I'm 100% sure that the conversion between context spaces is correct) and added a ComponentListener to monitor changes to the "target" component
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import java.awt.*;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
public class Main {
private Dimension pSize = new Dimension(100, 100);
private JFrame frame = new JFrame();
private JLabel content = new JLabel("Grief");
private JPanel content2 = new JPanel();
private SidePane sidePane = new SidePane();
private GlassPane glass = new GlassPane();
private Menu menu = new Menu();
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
content.setBackground(Color.green);
content.setPreferredSize(pSize);
content.setOpaque(true);
//setup frame basics
frame.setPreferredSize(new Dimension(500, 500));
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setGlassPane(glass);
frame.add(new MainPane());
// glass.setNewLocation();
// glass.revalidate();
frame.getGlassPane().setVisible(true);
// glass.setNewLocation();
frame.pack();
frame.setVisible(true);
}
});
}
public class MainPane extends JPanel {
public MainPane() {
//this.setBackground(Color.orange);
this.setLayout(new BorderLayout());
this.add(sidePane, BorderLayout.WEST);
this.add(menu, BorderLayout.NORTH);
}
}
public class SidePane extends JPanel {
public SidePane() {
FlowLayout f1 = new FlowLayout(FlowLayout.LEADING);
this.setLayout(f1);
this.setBackground(Color.blue);
this.add(content);
}
}
public class Menu extends JPanel {
public Menu() {
this.setBackground(Color.orange);
}
}
public class GlassPane extends JPanel {
private Rectangle target;
public GlassPane() {
this.setOpaque(false);
setLayout(null);
content2.setBackground(Color.BLACK);
content2.setPreferredSize(pSize);
content2.setOpaque(true);
add(content2);
content.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
updateOverlay();
}
#Override
public void componentMoved(ComponentEvent e) {
updateOverlay();
}
});
}
protected void updateOverlay() {
// Rectangle t = new Rectangle();
// t.setBounds((int) content.getLocation().getX(), (int) content.getLocation().getY(), content.getWidth(), content.getHeight());
// Rectangle r = SwingUtilities.convertRectangle(content.getParent(), content.getBounds(), this);
// Rectangle r = SwingUtilities.convertRectangle(content.getParent(), content.getBounds(), this);
target = SwingUtilities.convertRectangle(content.getParent(), content.getBounds(), this);
content2.setBounds(target);
// r = SwingUtilities.convertRectangle(content.getParent(), t, this);
// int x = (int) r.getBounds().getX();
// x = (int) r.getX();
// int y = (int) (r.getY() + r.getHeight());
//
// content2.setBounds(x, y, 100, 100);
// this.add(content2);
}
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g.create();
if (target != null) {
g2d.setColor(Color.RED);
g2d.draw(target);
}
g2d.dispose();
}
}
}

If you have the coordinate within the component, transfer it to screen coordinates using your component's convertPointToScreen(). Afterwards you can transfer back to see where in the window it sits by using the frame's convertPointFromScreen().
Or eliminate one of the two steps by directly using convertPoint().

Fixed the positioning issue using #MadProgrammer 's method of SwingUtilities.convertRectangle and called a new method at the end of the constructor which positioned the tracker panel.
Created a separate class for the glass pane
private class GlassPane extends JPanel {
public GlassPane() {
this.setLayout(null);
}
public void setNewLocation() {
Rectangle r = SwingUtilities.convertRectangle(top, content.getBounds(), this);
JPanel content2 = new JPanel();
int x = (int) r.getBounds().getX();
x = (int) r.getX();
int y = (int) (r.getY() + r.getHeight() + 1);
content2.setBounds(x, y, 100,100);
this.add(content2);
}
}
And added a call to the new method setNewLocation() at the end of the constructor
public test() {
**...**
frame.pack();
frame.setVisible(true);
glass.setNewLocation();
}

How to make JScrollPane (In BorderLayout, containing JPanel) smoothly autoscroll

I'm trying to have a JPanel of varying size (potentially much wider than the standard screen) inside of a JScrollPanel. Currently it works out great, and I have configured the scrollbars to work fine manually, however I would like the JPanel to "scroll" constantly to the left, so that over time the whole thing is displayed. All of the answers I found are specific to JTextArea and use Carets, or use rectToVisible. Neither of these will work because I'm trying to scroll internally to a single JPanel.
I've included what I believe to be all of the relevant code below.
center is the JPanel (of which Grid is a subclass, used to paint specifically a grid with some specific cells colored) with a BorderLayout that I would like to autoscroll.
public GuiViewFrame(Song playMe) {
String[][] songArray = playMe.to2DArray();
this.displayPanel = new ConcreteGuiViewPanel(playMe);
main = new JPanel();
main.setLayout(new BorderLayout());
displayPanel.setLayout(new BorderLayout());
center = new Grid(playMe);
labels = new Labels(playMe);
horiz = new Horiz(playMe);
center.setPreferredSize(new Dimension(10 * songArray.length, 10 * songArray[0].length));
horiz.setPreferredSize(new Dimension(10 * songArray.length, 10));
horiz.setVisible(true);
main.add(center, BorderLayout.CENTER);
main.add(horiz, BorderLayout.NORTH);
scroll = new JScrollPane(main,
JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
add(scroll, BorderLayout.CENTER);
labels.setPreferredSize(new Dimension(20, 10 * songArray[0].length));
labels.setVisible(true);
add(labels, BorderLayout.WEST);
JScrollBar horiz = scroll.getHorizontalScrollBar();
InputMap im = horiz.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
im.put(KeyStroke.getKeyStroke("RIGHT"), "positiveUnitIncrement");
im.put(KeyStroke.getKeyStroke("LEFT"), "negativeUnitIncrement");
im.put(KeyStroke.getKeyStroke("HOME"), "minScroll");
im.put(KeyStroke.getKeyStroke("END"), "maxScroll");
this.setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
this.pack();
}
The project as a whole is to generate a view for playing music that combines MIDI and a GUI, but right now once MIDI plays enough of the song, the relevant notes are off screen. I would like to scroll at a rate to keep pace with MIDI.

You can set the value of the horizontal scrollbar to control what is currently visible:
JScrollBar horizontal = scroll.getHorizontalScrollBar();
horizontal.setValue( horizontal.getValue() + ??? );
You would need to use a Swing Timer to schedule the scrolling at an appropriate interval.
Simple example of using a Timer to scroll text:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class TimerTest extends JPanel implements ActionListener
{
JLabel timeLabel;
JLabel scrollLabel;
public TimerTest()
{
setLayout( new BorderLayout() );
timeLabel = new JLabel( new Date().toString() );
add(timeLabel, BorderLayout.NORTH);
scrollLabel = new JLabel( "Some continuously scrolling text!! " );
add(scrollLabel, BorderLayout.SOUTH);
int time = 1000;
javax.swing.Timer timer = new javax.swing.Timer(time, this);
timer.setInitialDelay(1);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
timeLabel.setText( new Date().toString() );
String oldText = scrollLabel.getText();
// Scroll right to left
String newText = oldText.substring(1) + oldText.substring(0, 1);
// Scroll left to right
// int length = oldText.length();
// String newText = oldText.substring(length-1, length)
// + oldText.substring(0, length-1);
scrollLabel.setText( newText );
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new TimerTest() );
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}

One possible solution might be to take advantage of JComponent#scrollRectToVisible and a Swing Timer
For example...
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.Scrollable;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ScrollTest {
public static void main(String[] args) {
new ScrollTest();
}
public ScrollTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JScrollPane(new TestPane()));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel implements Scrollable {
public TestPane() {
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JViewport viewport = (JViewport) getParent();
Rectangle viewRect = viewport.getViewRect();
if (viewRect.x + viewRect.width < getWidth()) {
viewRect.x += 2;
scrollRectToVisible(viewRect);
} else {
((Timer)e.getSource()).stop();
}
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(1000, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawLine(0, 0, getWidth(), getHeight());
g2d.dispose();
}
#Override
public Dimension getPreferredScrollableViewportSize() {
return new Dimension(200, 200);
}
#Override
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
return 64;
}
#Override
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return 64;
}
#Override
public boolean getScrollableTracksViewportWidth() {
return getPreferredSize().width <= getParent().getSize().width;
}
#Override
public boolean getScrollableTracksViewportHeight() {
return getPreferredSize().height <= getParent().getSize().height;
}
}
}

Image not appearing in jbutton with wordGen

The image isn't being painted when this is run with WordGen, how do i fix this?
When I run this without wordgen I can get the image to appear. I'm not sure what i'm doing wrong since i'm not getting any errors.
Any help is appreciated.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class tfot extends JComponent{
private static final long serialVersionUID = 1L;
public static void main(final String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
showGUI(args);
}
});
}
public static void showGUI(String[] args) {
JPanel displayPanel = new JPanel();
JButton okButton = new JButton("Did You Know?");
okButton.setFont(new Font("Times", Font.TRUETYPE_FONT, 100));
final JLabel jLab = new JLabel();
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
jLab.setText(wordGen());
}
});
JPanel content = new JPanel();
content.setLayout(new BorderLayout());
content.add(displayPanel, BorderLayout.CENTER);
content.add(okButton, BorderLayout.SOUTH);
content.add(jLab, BorderLayout.NORTH);
JFrame window = new JFrame("Window");
window.setContentPane(content);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setSize(800, 600);
window.setLocation(400, 300);
window.setVisible(true);
}
#Override
public void paint(Graphics g) {
super.paint(g);
g.drawImage(Toolkit.getDefaultToolkit().getImage("Pictures/background1.png"), 0, 0, this);
}
public static String wordGen() {
String[] wordListOne = {"generic text","hi",};
int oneLength = wordListOne.length;
int rand1 = (int) (Math.random() * oneLength);
String phrase = wordListOne[rand1] + " ";
return phrase;
}
}

First...
Don't load resources or perform long running tasks within the paint methods, these may be called a number of times in quick succession. Instead, load the images before hand and paint them as needed...
public Tfot() {
setLayout(new BorderLayout());
try {
background = ImageIO.read(new File("pictures/background1.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
g.drawImage(background, 0, 0, this);
}
}
Generally, you are discouraged from overriding paint and instead should use paintComponent, lots of reasons, but generally, this is where the background is painted...
Second...
You need to add Tfot to something that is displayable, otherwise it will never be painted
JFrame window = new JFrame("Window");
window.setContentPane(new Tfot());
window.add(content);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setSize(800, 600);
window.setLocation(400, 300);
window.setVisible(true);
Thrid...
JPanel by default is not transparent, you need to set it's opaque property to false
JPanel displayPanel = new JPanel();
displayPanel.setOpaque(false);
//...
JPanel content = new JPanel();
content.setOpaque(false);
Then it will allow what ever is below it to show up (ie, the background image)
Take a look at Painting in AWT and Swing, Performing Custom Painting and Reading/Loading an Image for more details
Fourth...
You need to learn the language basics for embarking on advance topics like GUI and custom painting, without this basic knowledge, this topics will bite you hard.
You need to declare background as a instance field of the class Tfot
private BufferedImage background;
public Tfot() {
Updated - Fully runnable example
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Tfot extends JComponent {
private static final long serialVersionUID = 1L;
public static void main(final String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
showGUI(args);
}
});
}
public static void showGUI(String[] args) {
JPanel displayPanel = new JPanel();
displayPanel.setOpaque(false);
JButton okButton = new JButton("Did You Know?");
okButton.setFont(new Font("Times", Font.TRUETYPE_FONT, 100));
final JLabel jLab = new JLabel();
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
jLab.setText(wordGen());
}
});
JPanel content = new JPanel();
content.setOpaque(false);
content.setLayout(new BorderLayout());
content.add(displayPanel, BorderLayout.CENTER);
content.add(okButton, BorderLayout.SOUTH);
content.add(jLab, BorderLayout.NORTH);
Tfot tfot = new Tfot();
tfot.setLayout(new BorderLayout());
tfot.add(content);
JFrame window = new JFrame("Window");
window.setContentPane(tfot);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setSize(800, 600);
window.setLocation(400, 300);
window.setVisible(true);
}
private BufferedImage background;
public Tfot() {
try {
background = ImageIO.read(new File("Pictures/background1.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(background, 0, 0, this);
}
public static String wordGen() {
String[] wordListOne = {"generic text", "hi",};
int oneLength = wordListOne.length;
int rand1 = (int) (Math.random() * oneLength);
String phrase = wordListOne[rand1] + " ";
return phrase;
}
}

JPanel in the middle of the frame

I'm trying to put my jpanel in the middle of the frame... so when the user try to change the size of the window frame, it remain in the middle...
something like this:
so if i change size it have to remain in the middle:
i Tried to change the layout of my contentPane with the BorderLayout and put my jpanel in the center position... but when i change size of my frame the panel go in the top left corner.
In my windows builder the situation is this:
my jpanel have to work exactly how works the redbox. i tried everything but the result is everytime the same:
this is my code:
package StudApp;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JTextPane;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.SwingConstants;
import java.awt.Color;
import javax.swing.JTextArea;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class StudApp {
private JFrame frame;
private JPanel homeFirstRun;
private ArrayList<Corso> corsi = new ArrayList<Corso>();
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new StudApp();
}
});
}
/**
* Create the frame.
*/
public StudApp() {
frame = new JFrame("Student Note");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(100, 100, 450, 300);
JMenuBar menuBar = new JMenuBar();
frame.setJMenuBar(menuBar);
JMenu menuHelp = new JMenu("Help");
menuBar.add(menuHelp);
JMenuItem menuIstrStud = new JMenuItem("Intructions Student Note");
menuIstrStud.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
frame.remove(homeFirstRun);
frame.revalidate();
frame.repaint();
homeFirstRun = null;
}
});
menuHelp.add(menuIstrStud);
homeFirstRun = new JPanel();
homeFirstRun.setBorder(new EmptyBorder(5, 5, 5, 5));
homeFirstRun.setLayout(null);
frame.getContentPane().add(homeFirstRun);
JLabel welcomeMessage = new JLabel("Welcome to Student Note");
welcomeMessage.setBounds(5, 5, 424, 18);
welcomeMessage.setForeground(Color.DARK_GRAY);
welcomeMessage.setHorizontalAlignment(SwingConstants.CENTER);
welcomeMessage.setFont(new Font("Verdana", Font.BOLD, 14));
homeFirstRun.add(welcomeMessage);
JTextArea welcomeTextArea = new JTextArea();
welcomeTextArea.setFont(new Font("Verdana", Font.PLAIN, 13));
welcomeTextArea.setText(" I think it's your first time here.\n\n"
+ " So the first step is to create a new course to\n insert your grades.\n\n"
+ " If you want my advice, read how this program\n works in the help section (it is very simple),\n "
+ "just 2 minutes ... believe me");
welcomeTextArea.setEditable(false);
welcomeTextArea.setBounds(27, 34, 381, 184);
homeFirstRun.add(welcomeTextArea);
frame.setVisible(true);
}
}

There are several ways to do this, but one of the easiest is to give the contentPane a GridBagLayout, and then add your JPanel of interest with no GridBagConstraints. If the JPanel of interest is the only thing added to this container, this will then place that JPanel into a central position.
e.g.,
import java.awt.*;
import javax.swing.*;
public class CentralPanel {
private static void createAndShowGui() {
JFrame frame = new JFrame("CentralPanel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new MyContentPane());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyContentPane extends JPanel {
private static final int PREF_W = 700;
private static final int PREF_H = 550;
public MyContentPane() {
setLayout(new GridBagLayout());
add(new JPanelOfInterest());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
}
class JPanelOfInterest extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
public JPanelOfInterest() {
setBorder(BorderFactory.createTitledBorder("JPanel of Interest"));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
}

JPanel Possibly Overlapping?

So I have this problem with my code. Whenever I load up the game there is a red square in the center of the screen, and I have not programmed it to do so. I have tried to find the error for hours but I just can't see it. I think it has to do with the panels or something. The second thing is that when I press the button to draw the grid, only a small line appears. It is programmed to be much bigger than what it is, and it is not in the right location either. Below is all my code, and any help is greatly appreciated!!
package com.theDevCorner;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
public class Game extends JPanel implements ActionListener {
public static JButton grid = new JButton("Show Grid");
public static JPanel drawArea = new JPanel();
public static JMenuBar menu = new JMenuBar();
public static JPanel notDrawn = new JPanel();
public static boolean gridPressed = false;
public Game() {
grid.addActionListener(this);
}
public static void main(String args[]) {
Game game = new Game();
JFrame frame = new JFrame();
frame.setVisible(true);
frame.setSize(new Dimension(
Toolkit.getDefaultToolkit().getScreenSize().width, Toolkit
.getDefaultToolkit().getScreenSize().height));
frame.setTitle("Game");
frame.setAlwaysOnTop(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
menu.setSize(new Dimension(1600, 20));
menu.setLocation(0, 0);
notDrawn.setBackground(new Color(255, 0, 50));
notDrawn.setSize(100, 900);
notDrawn.add(grid);
notDrawn.setLayout(null);
grid.setSize(new Dimension(100, 25));
grid.setLocation(0, 25);
drawArea.setSize(new Dimension((Toolkit.getDefaultToolkit()
.getScreenSize().width), Toolkit.getDefaultToolkit()
.getScreenSize().height));
drawArea.setLocation(100, 0);
drawArea.setBackground(Color.black);
drawArea.add(menu);
drawArea.add(game);
frame.add(drawArea);
frame.add(notDrawn);
}
public void paint(Graphics g) {
Game game = new Game();
if (gridPressed) {
Game.drawGrid(0, 0, g);
}
g.dispose();
repaint();
}
public static void drawGrid(int x, int y, Graphics g) {
g.setColor(Color.white);
g.drawLine(x, y, 50, 300);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == grid && gridPressed == true) {
gridPressed = false;
System.out.println("Unpressed");
}
if (e.getSource() == grid) {
gridPressed = true;
System.out.println("Pressed");
}
}
}

There are a number of problems...
The red "square" you are seeing is actually your grid button. The reason it's red is because of your paint method.
Graphics is a shared resource, that is, each component that is painted on the screen shares the same Graphics context. Because you chose to dispose of the context and because you've failed to honor the paint chain, you've basically screwed it up.
Don't EVER dispose of a Graphics context you didn't create. It will prevent anything from being painted to it again. Always call super.paintXxx. The paint chain is complex and does a lot of very important work. If you're going to ignore it, be ready to have to re-implement it.
null layouts are vary rarely the right choice, especially when you're laying out components. You need to separate your components from your custom painting, otherwise the components will appear above the custom painting.
This frame.setSize(new Dimension(Toolkit.getDefaultToolkit().getScreenSize().width, Toolkit.getDefaultToolkit().getScreenSize().height)) is not the way to maximize a window. This does not take into consideration the possibility of things like tasks bars. Instead use Frame#setExtendedState
As Andreas has already commented, you actionPerformed logic is wrong. You should be using an if-statement or simply flipping the boolean logic...
Updated with simple example
ps- static is not your friend here...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Game extends JPanel implements ActionListener {
private GridPane gridPane;
public Game() {
setLayout(new BorderLayout());
SideBarPane sideBar = new SideBarPane();
sideBar.addActionListener(this);
add(sideBar, BorderLayout.WEST);
gridPane = new GridPane();
add(gridPane);
}
public static void main(String args[]) {
Game game = new Game();
JFrame frame = new JFrame();
frame.setVisible(true);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setTitle("Game");
frame.setAlwaysOnTop(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(game);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equalsIgnoreCase("grid")) {
gridPane.setGridOn(!gridPane.isGridOn());
}
}
public class GridPane extends JPanel {
private boolean gridOn = false;
public GridPane() {
setBackground(Color.BLACK);
}
public boolean isGridOn() {
return gridOn;
}
public void setGridOn(boolean value) {
if (value != gridOn) {
this.gridOn = value;
repaint();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (gridOn) {
g.setColor(Color.white);
g.drawLine(0, 0, 50, 300);
}
}
}
public class SideBarPane extends JPanel {
public JButton grid;
public SideBarPane() {
setBackground(new Color(255, 0, 50));
setLayout(new GridBagLayout());
grid = new JButton("Show Grid");
grid.setActionCommand("grid");
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.NORTH;
gbc.weighty = 1;
add(grid, gbc);
}
public void addActionListener(ActionListener listener) {
grid.addActionListener(listener);
}
}
}