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java- repaint() method is misbehaving - 2?

This question is an extension of java- repaint() method is misbehaving?
(Reading it, is optional)
I am working on a Music Player
I am using a JSlider as seek bar and using a JLabel to draw text on screen, such as song name.
I am new to Graphics2D
Here's the minimized code:
public class JSliderDemo extends JFrame
{
JLabel label;
JSlider seek = new JSlider();
int y = 10;
public JSliderDemo()
{
setSize(400, 400);
setLocationRelativeTo(null);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
createWindow();
setVisible(true);
startThread();
}
public void createWindow()
{
JPanel panel = new JPanel(new BorderLayout());
panel.setOpaque(true);
panel.setBackground(Color.BLUE);
panel.setBorder(new LineBorder(Color.YELLOW));
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new Dimension(300, 310));
label = new Component();
label.setSize(300, 300);
createSlider();
layeredPane.add(seek, new Integer(50));
layeredPane.add(label, new Integer(100));
panel.add(layeredPane);
add(panel);
}
protected void createSlider()
{
seek.setUI(new SeekBar(seek, 300, 10, new Dimension(20, 20), 5,
Color.DARK_GRAY, Color.RED, Color.RED));
seek.setOrientation(JProgressBar.HORIZONTAL);
seek.setOpaque(false);
seek.setLocation(10, 50);
seek.setSize(300, 20);
seek.setMajorTickSpacing(0);
seek.setMinorTickSpacing(0);
seek.setMinimum(0);
seek.setMaximum(1000);
seek.setBorder(new MatteBorder(5, 5, 5, 5, Color.CYAN));
}
protected void startThread()
{
Thread thread = new Thread(new Runnable(){
#Override
public void run()
{
try
{
while(true)
{
if(y == label.getHeight()){y = 1;}
label.repaint();
y += 1;
Thread.sleep(100);
}
}
catch(Exception ex){}
}
});
thread.start();
}
protected class Component extends JLabel
{
#Override
public void paintComponent(Graphics g)
{
Graphics2D gr = (Graphics2D) g;
gr.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
gr.setColor(Color.RED);
gr.setFont(new Font("Calibri", Font.PLAIN, 16));
gr.drawString("Song Name", 50, y);
gr.dispose();
}
}
public static void main(String[] args)
{
new JSliderDemo();
}
}
The problem is, when I call repaint() for JLabel it automatically repaints JSlider with it even though JSlider is not included in JLabel.
Output :
Slider re-painted
Slider re-painted
Slider re-painted
Slider re-painted
Slider re-painted
Slider re-painted.........
Now if I remove label.repaint() from the Thread, then the JSlider is not re-painted.
Output:
Slider re-painted
Slider re-painted
Is the repaint() method supposed to work like this?
In my last question, I was told to use Layout Manager and when I did use GridLayout just for checking if it's the solution, then it worked!
Only JLabel was repainted.
But I want to overlap JLabel on JSlider, so I thought of using JLayeredPane. And now, the problem is back.
How can I solve this?
Bottom Line : How can I overlap JLabel on JSlider without leading to repaint() method misbehave ?
OR
Does the repaint() method work like this?

As was already mentioned in the comments, the reason for your JSlider being repainted is that it has overlapping bounds with the JLabel. Even though your label doesn't paint over the area of the slider swing will still mark the overlapping area as dirty (i.e. the overlapping part of the slider will need to be repainted) because swing doesn't know that you are only painting in one part of the component.
To reduce the amount of repaints you will need to make the size of your JLabel smaller. Preferably only as large as it needs to be by invoking its getPreferredSize() method. You'll then be able to move the text by moving the location of the label.
Also you shouldn't be doing updates to the gui in a plain Thread. Use javax.swing.Timer instead. It ensures that all updates to the gui happen on the swing event thread, which is where they should be made.
After making these adjustments to your code the slider is only repainted while the label is actually visually over the slider.
public class JSliderDemo extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(JSliderDemo::new);
}
private final JLabel label = new CustomLabel();
public JSliderDemo() {
setSize(400, 400);
setLocationRelativeTo(null);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
createWindow();
setVisible(true);
startTimer();
}
public void createWindow() {
JPanel panel = new JPanel(new BorderLayout());
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new Dimension(300, 310));
label.setLocation(0, 0);
label.setBorder(new LineBorder(Color.RED));
label.setSize(label.getPreferredSize());
layeredPane.add(createSlider(), Integer.valueOf(50));
layeredPane.add(label, Integer.valueOf(100));
panel.add(layeredPane);
setContentPane(panel);
}
protected JSlider createSlider() {
JSlider seek = new CustomSlider();
seek.setOrientation(JProgressBar.HORIZONTAL);
seek.setOpaque(false);
seek.setLocation(10, 50);
seek.setSize(300, 20);
seek.setMajorTickSpacing(0);
seek.setMinorTickSpacing(0);
seek.setMinimum(0);
seek.setMaximum(1000);
seek.setBorder(new LineBorder(Color.BLUE));
return seek;
}
private void startTimer() {
new Timer(100, e -> {
int y = label.getY();
int maxY = label.getParent().getHeight();
if (y == maxY) {
y = -label.getHeight();
}
label.setLocation(label.getX(), y + 1);
label.repaint();
}).start();
}
private static class CustomLabel extends JLabel {
protected CustomLabel() {
setFont(new Font("Calibri", Font.PLAIN, 16));
setText("Song Name");
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("Painting Label");
}
}
protected static class CustomSlider extends JSlider {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("Painting Slider");
}
}
}

JButton responds in JFrame, but not in a JPanel

I'm new to java and I'm trying to figure out how action listeners and buttons work. I've found that I can get a working JButton if I put it directly into my JFrame object. But if I put it in a JPanel within that JFrame, it won't respond. Why is that?
Main.java
public class Main {
private static Frame f = new Frame();
public static void main(String[] args) {}
}
Frame.java
public class Frame extends JFrame {
private final int WIDTH = 640, HEIGHT = 480;
private Panel p = new Panel();
Frame() {
super("Java Program");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(WIDTH, HEIGHT);
this.setLayout(null);
this.setLocationRelativeTo(null);
this.setVisible(true);
}
public void paint(Graphics g) {
super.paint(g);
p.paintComponent(g);
}
}
Panel.java
public class Panel extends JPanel {
JButton b = new JButton("Button");
Panel() {
b.setBounds(0, 0, 200, 100);
add(b);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
b.setText("Pressed");
}
});
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
b.paint(g);
}
}

I am not a Swing expert so I can't really explain why it does not work. It seems like an unresponsive button is painted on top of you button. I tweaked it a little and here are a few modifications to get it to work:
Add the panel to the Frame: add(p);
Remove the this.setLayout(null); line, it seems to mess up the frame
To set the size of the Frame, use setPreferredSize: this.setPreferredSize(new Dimension(WIDTH, HEIGHT));
You also need to call pack() at then end of your Frame constructor.
And you need to remove b.paint(g) from your Panel.paintComponent(), this seems to be what paints the "unresponsive" button, (see image at the end of the answer).
Optionally, you can remove the paint() from the Frame, it does nothing more than the JFrame's one
Here is a modified working version:
class Frame extends JFrame {
private final int WIDTH = 640, HEIGHT = 480;
private Panel p = new Panel();
Frame() {
super("Java Program");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setPreferredSize(new Dimension(WIDTH, HEIGHT));
this.setLocationRelativeTo(null);
this.setVisible(true);
// add the panel to the frame
add(p);
pack();
}
}
class Panel extends JPanel {
JButton b = new JButton("Button");
Panel() {
b.setBounds(0, 0, 200, 100);
add(b);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
b.setText("Pressed");
}
});
}
// You can also get rid of this method,
// I just leave it here to show that I removed the b.paint(g) line
public void paintComponent(Graphics g) {
super.paintComponent(g);
}
}
Here is what the same code shows if you leave b.paint(g) in Panel.paintComponent(), as you can see there are 2 buttons, the one in the corner does not work.

ActionListener to draw shapes on separate panel

I want my GUI to draw circles/rectangles on the exact position I coded in the method paintComponent when I click on the respective buttons.
But I just don't know how to go on. What should I tell actionPerformed to do? Trying for a few hours to figure out a way, but I'm only getting errors.
public class Kreise extends JFrame {
Kreise() {
setLayout(new GridLayout(2, 1));
JLabel label = new JLabel("Draw Circ / Rect here: ");
label.setLayout(new FlowLayout(FlowLayout.CENTER));
JPanel jp1 = new JPanel();
jp1.setBackground(Color.LIGHT_GRAY);;
jp1.add(label);
JPanel jp2 = new JPanel(new FlowLayout());
JButton circ = new JButton("Circle");
JButton rect = new JButton("Rectangle");
circ.addActionListener(new KRListener(true));
rect.addActionListener(new KRListener(false));
jp2.add(circ);
jp2.add(rect);
MyPanel obj = new MyPanel();
jp1.add(obj);
add(jp1);
add(jp2);
setSize(400, 250);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public class MyPanel extends JPanel {
public boolean circleZ = true;
public void paintComponent(Graphics g) {
if (circleZ = true) {
super.paintComponent(g);
g.drawOval(150, 50, 50, 50);
} else if (circleZ = false) {
super.paintComponent(g);
g.drawRect(150, 50, 50, 50);
}
}
}
public class KRListener implements ActionListener {
boolean b;
KRListener(boolean b) {
this.b = b;
}
public void actionPerformed(ActionEvent e) {
?
}
}
public static void main(String[] args) {
new Kreise();
}
}

Presuming I understand the question clearly (you wish to toggle between the a rectangle or circle), in the ActionListener implementation you need to:
Toggle the appropriate boolean value
Call repaint on the JPanel instance that performs the painting
One way to accomplish these steps is to have a single toggle JButton, and pass an instance of the JPanel used for drawing to your ActionListener implementation, which can be used to accomplish both steps above:
public class KRListener implements ActionListener {
private MyPanel panel;
KRListener(MyPanel panel) {
this.panel = panel;
}
#Override
public void actionPerformed(ActionEvent e) {
panel.circleZ = !panel.circleZ;
panel.repaint();
}
}
And when you paint:
if ( circleZ ){
g.drawOval(150, 50, 50, 50);
}else{
g.drawRect(150, 50, 50, 50);
}

I dont know what you are using the global boolean variable b for But I noticed that you have to call the repaint() method when you press the Button.
public class KRListener implements ActionListener {
boolean b;
KRListener(boolean b) {
this.b = b;
}
#Override
public void actionPerformed(ActionEvent e){
//add some code here to change properties of the drawing before calling the repaint method?
repaint();
}
}

Panel added to BorderLayout.CENTER does not occupy remaining space

I am currently learning to program GUI in Java, and I have a problem where the CENTER component does not occupy the remaining space in the frame. From what I've read BorderLayout will grant components in north/south their preferred height and the stretch it out to the edges, and west/east will be the opposite. The center component will then get whatever space is left. What I am trying to do is to create a simple window with a panel in the north region, and a panel in the center region. I give each their own background color so I can easily see the space they are given. However, instead of getting a window with a yellow top bar and the remaining space being occupied by the magenta panel, I get this.
The top panel is just a regular JPanel, but the center panel is a class extending JPanel which overrides paintComponent and fills the panel with a color. If I hardcode in a bigger area in the fillRect() it will actually fill the window. So I suspect there's something wrong happening when I call getHeight() and getWidth in the method. It also might be worth mentioning that the dawPanel always will paint a perfect square, if I resize the window into a rectangle longer on the Y-aksis the gap will appear on the bottom instead.
So my question is, how can I get the component added to the Borderlayout.CENTER to occupy all remaining space in the frame.contentPane()?
package oblig1;
import java.awt.*;
import javax.swing.*;
public class Oblig1
{
JFrame frame;
JPanel infoPanel;
DrawingPanel drawPanel;
public static void main(String[] args)
{
Oblig1 game = new Oblig1();
}
public Oblig1()
{
frame = new JFrame("Parachute Game");
frame.setSize(860, 640);
infoPanel = new JPanel();
drawPanel = new DrawingPanel();
infoPanel.setBackground(Color.yellow);
infoPanel.setPreferredSize(new Dimension(840, 20));
infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));
drawPanel.setPreferredSize(new Dimension(840, 620));
frame.getContentPane().add(infoPanel, BorderLayout.NORTH);
frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// frame.setResizable(false);
frame.setVisible(true);
}
//This class represents the panel that paints all animated parts of the game
public class DrawingPanel extends JPanel
{
public DrawingPanel()
{
setDoubleBuffered(true);
}
#Override
protected void paintComponent(Graphics g)
{
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.MAGENTA);
g2d.fillRect(0, 0, drawPanel.getHeight(), drawPanel.getWidth());
}
}
}

issue came from two code lines (and one code line missed
infoPanel.setPreferredSize(new Dimension(840, 20));
and
infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));
BoxLayout required Min, Max and PreferredSize, otherwise missed Dimensions collided with another PreferredSize, in this case (infoPanel.setPreferredSize(new Dimension(840, 20)); ) that is laid in JFrame that uses BorderLayout
remove infoPanel.setPreferredSize(new Dimension(840, 20));, or its widht must be less than PreferredSize used for JPanel
painting in Swing by default never returns PreferredSize correctly back to the container, you jave to override getPreferredSize, for BoxLayout min, max and preferred size
use JFrame.pack() instead of sizing for min,max and preferredSize directly to the JComponents or container, nor to setSize for JFrame
not true at all, to see my EDIT --> use another LayoutManager for JPanel to reduce funny issue with painting if is JFrame resized
your paintComponent missed important code line super.paintComponent(g);
e.g.
import java.awt.*;
import javax.swing.*;
public class Oblig1 {
JFrame frame;
JPanel infoPanel;
DrawingPanel drawPanel;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Oblig1();
}
});
}
public Oblig1() {
frame = new JFrame("Parachute Game");
//frame.setSize(860, 640);
infoPanel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(20, 20);
}
};
drawPanel = new DrawingPanel();
infoPanel.setBackground(Color.yellow);
//drawPanel.setPreferredSize(new Dimension(840, 20));
infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.X_AXIS));
//drawPanel.setPreferredSize(new Dimension(840, 620));
frame.getContentPane().add(infoPanel, BorderLayout.NORTH);
frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
//This class represents the panel that paints all animated parts of the game
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawingPanel() {
setDoubleBuffered(true);
}
#Override
public Dimension getMinimumSize() {
return new Dimension(300, 300);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public Dimension getMaximumSize() {
return new Dimension(300, 300);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.MAGENTA);
//g2d.fillRect(0, 0, getHeight(), getWidth());
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
}
EDIT
to my point, is simple wrong
use another LayoutManager for JPanel to reduce funny issue with painting if is JFrame resized
there are wrong, reversed parameters for Height and Width, wrong code line g2d.fillRect(0, 0, getHeight(), getWidth()); should be g2d.fillRect(0, 0, getWidth(), getHeight());

Adding JLabels to a Panel inside a Panel inside another Panel

I have one "main" panel. I'd like to have a "side" panel inside the main one. The side is composed of two other panels, let's call one graphicPanel and one supportPanel. I'm trying to add labels to the SupportPanel from the main one, but no changes happen.
Here is my side panel:
public class LateralSupportPane extends JPanel{
private final static int WIDTH = 240;
private final static int HEIGHT = 740;
private GraphicPanel gp;
private SupportPanel sp;
public LateralSupportPane(){
this.gp = new GraphicPanel();
this.sp = new SupportPanel();
this.setPreferredSize(new Dimension(WIDTH, HEIGHT));
this.setLayout(new GridLayout(2, 1));
//this.setBorder(BorderFactory.createLineBorder(Color.black));
this.add(gp);
this.add(sp);
this.setVisible(true);
}
public void addLabel(String label){
sp.addLabel(label);
}
public void paintComponent(Graphics g){
super.paintComponent(g);
gp.paintComponent(g);
}
public void addLabel(String label){
sp.addLabel(label);
}
Here my supportPanel:
public class SupportPanel extends JPanel{
private JLabel label;
private final static int WIDTH = 240;
private final static int HEIGHT = 370;
public SupportPanel(){
this.setPreferredSize(new Dimension(WIDTH, HEIGHT));
label = new JLabel();
label.setText("<html>BlaBla</html>");
this.setLayout(new GridLayout(10, 1));
this.add(label);
this.setVisible(true);
}
public JLabel getLabel() {
return label;
}
public void addLabel(String text){
JLabel label = new JLabel(text);
if(this.getComponentCount() < 10){
this.add(label);
} else {
this.remove(0);
this.add(label);
}
}
From the main panel I call the addLabel of the side panel.
EDIT: Here is the frame with all panels. The board itself is a panel added into a frame. The board also has another panel, that are the black rectangle and the area where the string is, together. Then the side panel is composed by 2 other panels, the GraphicPanel (the black rectangle) and the supportPanel, that is the area where I'd like to have my labels.
Board
Validating all panels made no progress.

Not sure if i undurstend it correctly, but it seams, that you have to validate your panels after inserting new label;
public static void main(String[] args) {
JFrame frame = new JFrame("test");
frame.setSize(900, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new CardLayout());
frame.setVisible(true);
LateralSupportPane p = new LateralSupportPane();
frame.add(p);
frame.validate();
p.addLabel("test 2");
p.validate();
}
as you see, after adding a label, validation is performed and object is painted on form.
your method addLabel(String label) should have this method called at end of it.