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Repaint method not working on JComponent java swing

I want to have a text field to input an integer, then select 1) Grow or 2) Shrink, and then click the button so that the circle gets redrawn on the screen based on the selected options.
I don't know why it isn't repaining. (Don't worry about the layout, just want to get it to work first)
My Frame:
public class Main {
public static void main(String[] args) {
var frame = new JFrame();
frame.setSize(400,400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
var circleComp = new circleComponent();
var panel1 = new JPanel();
var multiplierLabel = new JLabel("Grow Multiplier");
var multiplierField = new JTextField(20);
var radio1 = new JRadioButton("Grow Circle");
var radio2 = new JRadioButton("Shrink Circle");
var bg = new ButtonGroup();
bg.add(radio1);
bg.add(radio2);
JButton button = new JButton("Rivizato");
button.addActionListener(
new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(radio1.isSelected()){
rrComp.repaint(0,0,Integer.parseInt(multiplierField.getText())*rrComp.getWidth(), Integer.parseInt(multiplierField.getText())*rrComp.getHeight());
}
else if(radio2.isSelected()){
rrComp.repaint(0,0,Integer.parseInt(multiplierField.getText())/rrComp.getWidth(), Integer.parseInt(multiplierField.getText())/rrComp.getHeight());
}
}
}
);
panel1.add(multiplierLabel);
panel1.add(multiplierField);
panel1.add(button);
panel1.add(radio1);
panel1.add(radio2);
frame.add(panel1);
frame.add(circleComp);
}
}
My CircleComponent class:
public class CircleComponent extends JComponent {
public void paintComponent(Graphics g){
super.paintComponent(g);
var g2 = (Graphics2D) g;
var circle = new Ellipse2D.Double(0,0,100,100);
g2.draw(circle);
}
}

var circle = new Ellipse2D.Double(0,0,100,100); means that your circle will never change size.
You should also be careful with repaint(x, y, width, height) as it could leave regions of your component "dirty". Better to just use repaint.
As a conceptual example...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public final class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new MainPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class MainPane extends JPanel {
private CirclePane circlePane;
public MainPane() {
setLayout(new BorderLayout());
JPanel actionsPane = new JPanel(new GridBagLayout());
JButton growButton = new JButton("Grow");
growButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
circlePane.grow();
}
});
JButton shrinkButton = new JButton("Shrink");
shrinkButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
circlePane.shrink();
}
});
actionsPane.add(growButton);
actionsPane.add(shrinkButton);
circlePane = new CirclePane();
add(circlePane);
add(actionsPane, BorderLayout.SOUTH);
}
}
public class CirclePane extends JPanel {
private Ellipse2D circle;
public CirclePane() {
circle = new Ellipse2D.Double(0, 0, 100, 100);
}
public void grow() {
double width = circle.getWidth() + 10;
double height = circle.getHeight() + 10;
circle.setFrame(0, 0, width, height);
repaint();
}
public void shrink() {
double width = Math.max(0, circle.getWidth() - 10);
double height = Math.max(0, circle.getHeight() - 10);
circle.setFrame(0, 0, width, height);
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
double x = (getWidth() - circle.getWidth()) / 2d;
double y = (getHeight() - circle.getHeight()) / 2d;
g2d.translate(x, y);
g2d.draw(circle);
g2d.dispose();
}
}
}
nb: I know I've not used JTextField to specify the size of the circle, that's on purpose. You will need to adapt your requirements to work in a similar way - can you see where you might pass parameters to the CirclePane?

Adding two JPanels to JFrame, only one is visible

I have the following problem, when i want to add 2JPanels to my JFrame only one is visible, depending on which I added to the frame last. I overrided the JPanels default paintComponent() method on both of the JPanels. How can i fix this?
Code snippet:
Border:
public class BorderDrawer extends JPanel{
private int _width,_height;
BorderDrawer(int width,int height)
{
setOpaque(false);
_width = width;
_height = height;
}
#Override
protected void paintComponent(Graphics g) {
final int BUTTON_WIDTH = 20,BUTTON_HEIGHT = 20;
int MINES_HORIZONTALLY = _width;
int MINES_VERTICALLY = _height;
super.paintComponent(g);
try{
BufferedImage topLeftCorner = ImageIO.read(this.getClass().getResource("topLeftCorner.png"));
g.drawImage(topLeftCorner, 0, 0, null);
....// drawing other border components
}
}
Clock:
public class GraphicTimer extends JPanel{
Timer _aktTimer = null;
int seconds;
int _width = 0;
GraphicTimer(int width)
{
setSize(52, 31);
setOpaque(false);
_width = width;
int delay = 1000; //milliseconds
_aktTimer = new Timer(delay, taskPerformer);
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
try
{
final int BUTTON_WIDTH = 20,BUTTON_HEIGHT = 20;
int MINES_HORIZONTALLY = _width;
int HORIZONTAL_ENDING = 15+BUTTON_WIDTH*MINES_HORIZONTALLY;
BufferedImage clock = ImageIO.read(this.getClass().getResource("clock.png"));
g.drawImage(clock,HORIZONTAL_ENDING-54,22, null);
}
catch(IOException ex)
{
ex.printStackTrace();
}
}
....
}
JFrame:
public class DrawerField extends JFrame implements Serializable{
//...
public DrawerField()
{
super("MineSweeper");
_FIELD = new Field();
constructorInit();
}
public void constructorInit()
{
_buttons = new FieldButton[_height][_width];
_isMouseEventEnabled = true;
fieldPanel = new JPanel();
smilePanel = new JPanel();
//INITS
int fieldSizeWidth = (_width)*20;
int fieldSizeHeight = (_height)*20; // Magic size
fieldPanel.setSize(fieldSizeWidth,fieldSizeHeight); // 20x20
fieldPanel.setLocation(15, 70);
fieldPanel.setLayout(new GridLayout(_width,_height));
int fullWindowWidth = fieldSizeWidth+36;
int fullWindowHeight = fieldSizeHeight+142;
setSize(fullWindowWidth,fullWindowHeight);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
restartButton = new RestartButton(this);
smilePanel.setSize(34,34);
smilePanel.add(restartButton);
smilePanel.setLayout(new GridLayout(1,1));
smilePanel.setLocation((int)fullWindowWidth/2-(34/2)-1,20);
///INITIALS
for(int i = 0; i < _height; i++)
{
for(int j = 0; j < _width ; j++)
{
_buttons[i][j] = new FieldButton(_hidden[i][j],true,i,j,this);
fieldPanel.add(_buttons[i][j]);
}
}
add(smilePanel);
add(fieldPanel);
borderDrawer = new BorderDrawer(_width,_height);
_graphicTimer = new GraphicTimer(_width);
_graphicTimer.start();
add(_graphicTimer); // This is the two lines which change the result
add(borderDrawer);
MenuBar menuBar = new MenuBar(this);
setJMenuBar(menuBar);
setVisible(true);
}
//...
}
Easier and compilable example:
public class Main {
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(500, 500);
MyPanel panel1 = new MyPanel(30,30);
frame.add(panel1);
MyPanel panel2 = new MyPanel(70,30);
frame.add(panel2);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.repaint();
frame.setVisible(true);
}
public static class MyPanel extends JPanel
{
int _x,_y;
MyPanel(int x, int y)
{
_x = x; _y = y;
}
#Override
public void paint(Graphics g) {
g.drawOval(_x,_y,20,20);
}
}
}
My main goal is to add 2 circles to the JFrame without using any Layout.( As you can see in the example above I already have a lot of things on my JFrame that's why I don'T want to use layouts). The problem is the same in this example, when i add the 2nd circle the first is disappearing.

Its simple. Adding a panel in a frame adds it to the content pane of the frame. This contentpane has a default layout of BorderLayout which means, every time you add a panel, it gets added to the center of the content pane and gets replaces the previous one. This is the reason why you see only the last one. Its always good to use a Jpanel set to the layout of your choice put everything that needs to be shown on the screen in that panel. If you don't want to do that, you may also call getContentPane() from the frame and play with the returned instance of JPanel.

Here is the example code for you:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Frame extends JFrame {
public Frame() {
setTitle("Two panels");
setSize(new Dimension(500,500));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Here goes your code
JPanel p= (JPanel) getContentPane();
p.setLayout(new GridLayout(1,2)); //set your own layout
p.add(new MyPanel(Color.BLUE)); //add panel with blue border
p.add(new MyPanel(Color.GREEN));//add panel with green border
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Frame f= new Frame();
f.setVisible(true);
}
});
}
}
class MyPanel extends JPanel {
public MyPanel(Color color) {
setBorder(BorderFactory.createLineBorder(color));
}
}
Run it and see... You should be able to see something like this:

Layering a button over a painting

There is a window in which I want to place a button, and then paint the whole area beneath it. In other words, button should cover a piece of painting.
import java.awt.*;
import javax.swing.*;
class Window
{
private JFrame frame;
private JButton launchButton;
private JPanel pnllaunchButton;
private JPanel paintingPanel;
//width and height of client area
private Rectangle dim;
//w,h - width and height of the whole window
public Window(String title,int w,int h)
{
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocation(0,0);
frame.setMinimumSize( new Dimension(110,110));
frame.setSize(w, h);
frame.setVisible(true);
frame.setTitle(title);
frame.setResizable(false);
addLaunchButton();
}
private void addLaunchButton()
{
pnllaunchButton = new JPanel();
launchButton = new JButton("Plot!");
dim = new Rectangle();
frame.getContentPane().getBounds(dim);
pnllaunchButton.setBounds(dim.width-100,dim.height-25,100,25);
launchButton.setBounds(dim.width-100,dim.height-25,100,25);
pnllaunchButton.setLayout(null);
pnllaunchButton.add(launchButton);
frame.getContentPane().add(pnllaunchButton);
frame.getContentPane().setComponentZOrder(pnllaunchButton, new Integer(2));
}
public void drawCoordinateSystem()
{
paintingPanel = new JPanel();
paintingPanel.add(new CoordinateSystem());
frame.getContentPane().add(paintingPanel);
frame.getContentPane().setComponentZOrder(paintingPanel,new Integer(3));
}
}
class CoordinateSystem extends JPanel
{
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Dimension size = this.getSize();
g.setColor(Color.BLACK);
g.drawLine(0,size.height/2,size.width, size.height/2);
g.drawLine(size.width/2, 0, size.width/2, size.height);
}
}
public class GC {
public static void main(String[] args)
{
Window h = new Window("GC",800,600);
h.drawCoordinateSystem();
}
}
This code doesn't fulfill the specification. Program creates an empty window and outputs:
run:
Exception in thread "main" java.lang.IllegalArgumentException: illegal component position
at java.awt.Container.checkAdding(Container.java:504)
at java.awt.Container.setComponentZOrder(Container.java:759)
at Window.addLaunchButton(Window.java:46)
at Window.<init>(Window.java:26)
at GC.main(GC.java:10)
Could you point out my mistake? setComponentZOrder() method doesn't seem to be described precisely in javadoc.

Rename your class. The Window class is already part of the standard core Java libraries, and your class name could cause present or future problems.
Don't us null layouts and setBounds(...). This is bad, bad, bad, and will make it very difficult to maintain or upgrade your application. Instead, learn about and use the layout managers.
Consider making a JLabel the contentPane, make it opaque, give it a layout and an ImageIcon and add your components to it.
The ImageIcon can hold a BufferedImage with a grid.
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class MyWindow {
private static final int PREF_W = 800;
private static final int PREF_H = 600;
private static final Color COLOR0 = Color.red;
private static final Color COLOR1 = Color.blue;
private static final float COLOR_REPEAT_DIST = 30f;
private JLabel backGroundLabel = new JLabel();
public MyWindow() {
backGroundLabel.setOpaque(true);
backGroundLabel.setLayout(new BorderLayout());
int eb = 15;
BufferedImage bkgrndImg = createBkgrndImage();
ImageIcon icon = new ImageIcon(bkgrndImg);
backGroundLabel.setIcon(icon);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new FlowLayout(SwingConstants.RIGHT, eb, eb));
bottomPanel.setOpaque(false);
bottomPanel.add(new JButton("Plot"));
backGroundLabel.add(bottomPanel, BorderLayout.PAGE_END);
}
private BufferedImage createBkgrndImage() {
BufferedImage img = new BufferedImage(PREF_W, PREF_H, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setPaint(new GradientPaint(0f, 0f, COLOR0, COLOR_REPEAT_DIST, COLOR_REPEAT_DIST, COLOR1, true));
g2.fillRect(0, 0, PREF_W, PREF_H);
g2.dispose();
return img;
}
public JComponent getMainPane() {
return backGroundLabel;
}
private static void createAndShowGui() {
MyWindow mainPanel = new MyWindow();
JFrame frame = new JFrame("MyWindow");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainPane());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Which looks like so:

Pass an int instead of an Integer to the setComponentZOrder method.
private void addLaunchButton()
{
pnllaunchButton = new JPanel();
launchButton = new JButton("Plot!");
dim = new Rectangle();
frame.getContentPane().getBounds(dim);
pnllaunchButton.setBounds(dim.width-100,dim.height-25,100,25);
launchButton.setBounds(dim.width-100,dim.height-25,100,25);
pnllaunchButton.setLayout(null);
pnllaunchButton.add(launchButton);
frame.getContentPane().add(pnllaunchButton);
frame.getContentPane().setComponentZOrder(pnllaunchButton, 2);
}

paintComponent not changing shape

can someone take a look at my code below and tell me why, when I change the following two statements, I do not see a change on the rectangle that is painted. So if I change:
g.setColor(Color.black);
g.fillRect(l, w, 100, 100);
The program still prints a black rectangle with the same dimensions and in the same position that I first started with even though I change color to yellow or try to change the dimensions or location. I am BlueJ. The following is my full code:
import java.awt.*;
import javax.swing.*;
public class SwingPaintDemo2 extends JComponent {
public static boolean isWall = true;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
//System.out.println("Created GUI on EDT? "+
//SwingUtilities.isEventDispatchThread());
JFrame f = new JFrame("Swing Paint Demo");
JPanel MyPanel = new JPanel();
MyPanel.setBorder(BorderFactory.createEmptyBorder(1000, 1000, 1000, 1000));
MyPanel.setPreferredSize(new Dimension(250, 200));
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MyPanel());
f.pack();
f.setVisible(true);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
int l = 10;
int w = 10;
g.setColor(Color.black);
g.fillRect(l, w, 100, 100);
}
}
Any advice would be appreciated.

Your SSCCE doesnt compile where is MyPanel class or did you mean new SwingPaintDemo2()?
On the assumption you meant new SwingPaintDemo2():
The code does work just fine but the JFrame is sized very small:
because you dont give it any size and none of its components have a size as they do not have any components added to them, thus we must make the JComponent return a correct size so when we call pack() our JFrame is sized correctly
Solution
override getPreferredSize() of JComponent to return a width and height which fits all drawings.
Some suggestions though:
Dont extend JComponent rather extend JPanel
Here is an example (your code with above fixes implemented):
import java.awt.*;
import javax.swing.*;
public class SwingPaintDemo2 extends JPanel {
public static boolean isWall = true;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
//System.out.println("Created GUI on EDT? "+
//SwingUtilities.isEventDispatchThread());
JFrame f = new JFrame("Swing Paint Demo");
JPanel MyPanel = new JPanel();
MyPanel.setBorder(BorderFactory.createEmptyBorder(1000, 1000, 1000, 1000));
MyPanel.setPreferredSize(new Dimension(250, 200));
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new SwingPaintDemo2());
f.pack();
f.setVisible(true);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
int l = 10;
int w = 10;
g.setColor(Color.black);
g.fillRect(l, w, 100, 100);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(150, 150);
}
}

Java repainting when pushing a button

I've hit a wall (in my brain) trying to update my board on button presses. Am I right in thinking that the GameBoard class is the one that needs to be repaint()ed?
GameBoard.java
public class GameBoard extends Panel {
static Compass compass = new Compass();
private static final long serialVersionUID = 1;
Graphics2D g2d;
static final Dimension WINDOW_SIZE = new Dimension(1150, 800);
public void boardMaker() throws Exception {
JFrame frame = new JFrame("Display image");
JPanel panel = new JPanel();
/* unimportant stuff
.....
*/
//
DieRoll roll = new DieRoll("Roll Dies");
roll.setC(compass);
roll.setG2D(g2d);
//
Button button = new Button("new");
button.setGameBoard(this);
JPanel buttonPanel = new JPanel();
buttonPanel.add(button);
buttonPanel.add(roll);
buttonPanel.setPreferredSize(new Dimension(200,100));
frame.getContentPane().add(buttonPanel, BorderLayout.NORTH);
//
frame.getContentPane().add(panel);
frame.setVisible(true);
}
public void paint(Graphics g) {
// not important I think
}
}
Button.java
public class Button extends JButton implements ActionListener {
private static final long serialVersionUID = 1L;
JPanel panel = new JPanel();
JFrame frame = new JFrame();
Compass c = new Compass();
GameBoard gb = new GameBoard();
Button(String text) {
this.setText(text);
this.addActionListener(this);
}
void setGameBoard(GameBoard gb) {
this.gb = gb;
}
#Override
public void actionPerformed(ActionEvent e) {
gb.g2d.setColor(Color.black);
gb.g2d.fillRect(100, 100, 100, 200);
gb.repaint();
}
}
This gives a null pointer exception. So any idea how to repaint my GameBoard? I'm not mad if I've to rewrite everything because of stupidity! ;)
Thanks

You have the wrong idea about how to draw in Java. Components like Panels draw themselves, and all drawing takes place on the UI thread.
Check out this tutorial: docs.oracle.com/javase/tutorial/2d/index.html

The article Painting in AWT and Swing may offer some perspective on application-triggered painting. The example below illustrates the principle. Note that setForeground() calls repaint() automatically because the foreground color is a bound property, but you can always call it yourself.
import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;
public class SwingPaint {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame f = new JFrame();
final GamePanel gp = new GamePanel();
f.add(gp);
f.add(new JButton(new AbstractAction("Update") {
#Override
public void actionPerformed(ActionEvent e) {
gp.update();
}
}), BorderLayout.SOUTH);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
});
}
private static class GamePanel extends JPanel {
private static final Random r = new Random();
public GamePanel() {
this.setForeground(new Color(r.nextInt()));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(320, 240);
}
public void update() {
this.setForeground(new Color(r.nextInt()));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Dimension size = this.getSize();
int d = Math.min(size.width, size.height) - 10;
int x = (size.width - d) / 2;
int y = (size.height - d) / 2;
g.fillOval(x, y, d, d);
g.setColor(Color.blue);
g.drawOval(x, y, d, d);
}
}
}