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Painting method paints things from other components

I am trying to make a simple Java program with GUI using Java Swing.
I have painting panel (gPanel) in the center of the screen, panel with buttons (buttonSet) in the west and panel with labels (labelPanel) in the east. To paint over gPanel I use paintComponent method and since I have two buttons, which are supposed to draw different things (and change label on the right of the screen), I decided to put switch case in paintComponent method for it to choose the correct actual painting method.
When I run the program everything looks fine - program uses the first method to paint and there is a sampletext.png image shown in the middle of the screen with yellow background, as it should be. Button number 1 also uses this method to draw over gPanel, so pressing it draws the same thing.
Now Button number 2 uses the second painting method and this is where things go wrong. It draws sampleimage.png over the gPanel, but also parts of left and right panels (i.e. buttons from left buttonSet panel and orange colour that is background colour of side panels) are drawn, though it shouldn't happen. Also the whole gPanel becomes gray (I think it happens because of label on the right that becomes very long after pressing Button number 2, because when the label was shorter gPanel didn't turn gray and left the previously drawn things instead).
Pressing Button number 1 paints things from first method properly, so pressing it after pressing Button number 2 "reverts" the changes.
What do I have to do to make my second painting method work properly?
Also why adding border to buttonSet and labelPanel works but adding it to gPanel doesn't?
package com.inferjus.drawingproject;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.border.*;
/**
*
* #author inferjus
*/
public class DrawingProject
{
private JFrame frame;
private graphicPanel gPanel;
private JPanel buttonSet;
private JPanel labelPanel;
private JLabel label;
private int painter=0;
public static void main(String[] args)
{
DrawingProject program=new DrawingProject();
program.prepareGUI();
}
public int getPainter()
{
return painter;
}
public void setPainter(int x)
{
painter=x;
}
public void prepareGUI()
{
//setting JFrame and icon
frame=new JFrame("Drawing Project");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
try { frame.setIconImage(ImageIO.read(getClass().getResource("/resources/sampleicon.png")));}
catch (IOException e) { e.printStackTrace(); }
//border for components
Border bigBlackBorder=new LineBorder(Color.black, 3);
//setting JPanel (graphicPanel) for drawing images
gPanel=new graphicPanel();
gPanel.setBorder(bigBlackBorder); // <--- why it does not work?
//setting JPanel for buttons on the left of the screen
buttonSet=new JPanel();
buttonSet.setLayout(new BoxLayout(buttonSet, BoxLayout.Y_AXIS));
buttonSet.setBorder(bigBlackBorder);
//setting JButtons
JButton buttonOne=new JButton("Button number 1");
buttonOne.addActionListener(new buttonOneListener());
buttonSet.add(buttonOne);
buttonSet.setBackground(Color.orange);
JButton buttonTwo=new JButton("Button number 2");
buttonTwo.addActionListener(new buttonTwoListener());
buttonSet.add(buttonTwo);
//setting JLabels on the right of the screen
label=new JLabel("Default label");
label.setFont(new Font("Consolas", Font.PLAIN, 20));
labelPanel=new JPanel();
labelPanel.setLayout(new BoxLayout(labelPanel, BoxLayout.Y_AXIS));
labelPanel.setBackground(Color.orange);
labelPanel.setBorder(bigBlackBorder);
JLabel popeLabelTitle=new JLabel("What does the label say?");
popeLabelTitle.setFont(new Font("Consolas", Font.BOLD, 24));
//adding JLabels to labelPanel
labelPanel.add(BorderLayout.NORTH, popeLabelTitle);
labelPanel.add(BorderLayout.CENTER, label);
//adding components to JFrame
frame.getContentPane().add(BorderLayout.CENTER, gPanel);
frame.getContentPane().add(BorderLayout.EAST, labelPanel);
frame.getContentPane().add(BorderLayout.WEST, buttonSet);
frame.setVisible(true);
}
class graphicPanel extends JPanel
{
private BufferedImage sampletext=null;
private BufferedImage sampleimage=null;
#Override
public void paintComponent(Graphics g)
{
//for Button One paint sampletext.png, for Button Two paint sampleimage.png
switch (painter)
{
case 0:
paintSampletext(g);
break;
case 1:
paintSampleimage(g);
break;
}
}
//paint yellow background and put sampletext.png in the middle
private void paintSampletext(Graphics g)
{
if (sampletext==null)
{
gPanel.setSampletextPNG();
}
g.setColor(Color.yellow);
g.fillRect(0,0, gPanel.getWidth(), gPanel.getHeight());
g.drawImage(sampletext, gPanel.getWidth()/2-sampletext.getWidth()/2, gPanel.getHeight()/2-sampletext.getHeight()/2, this);
g.setColor(Color.black);
g.drawRect(gPanel.getWidth()/2-sampletext.getWidth()/2, gPanel.getHeight()/2-sampletext.getHeight()/2, sampletext.getWidth(), sampletext.getHeight());
g.dispose();
}
//paint sampleimage.png over what is already displayed
private void paintSampleimage(Graphics g)
{
if (sampleimage==null)
{
gPanel.setSampleimagePNG();
}
int x=(int)((Math.random()*gPanel.getWidth())-sampleimage.getWidth());
int y=(int)((Math.random()*gPanel.getHeight())-sampleimage.getHeight());
g.drawImage(sampleimage, x, y, gPanel);
g.dispose();
}
public void setSampletextPNG()
{
try { sampletext=ImageIO.read(getClass().getResource("/resources/sampletext.png")); }
catch (IOException ex) { System.out.println("Image error"); }
}
public void setSampleimagePNG()
{
try { sampleimage=ImageIO.read(getClass().getResource("/resources/sampleimage.png")); }
catch (IOException ex) { System.out.println("Image error"); }
}
}
class buttonOneListener implements ActionListener
{
#Override
public void actionPerformed(ActionEvent e)
{
label.setText("Reaction to button number 1: change of label.");
setPainter(0);
gPanel.repaint();
}
}
class buttonTwoListener implements ActionListener
{
#Override
public void actionPerformed(ActionEvent e)
{
label.setText("Reaction to button number 2: change of label + drawing images over gPanel.");
setPainter(1);
gPanel.repaint();
}
}
}
Tree of my project:
DrawingProject
-JRE System Library
-src
--com.inferjus.drawingproject
---DrawingProject.java
--resources
---sampleicon.png
---sampleimage.png
---sampletext.png
what shows after running the program by default or after pressing Button One
what shows after pressing Button Two one time
what shows after pressing Button Two a few times

Introduction
Oracle has a helpful tutorial, Creating a GUI With Swing. Skip the Learning Swing with the NetBeans IDE section.
I went ahead and created the following GUI. I created two BufferedImages for the text image and the plain image so I wouldn't have to read any external files.
Explanation
When I create a Swing GUI, I use the model-view-controller pattern. This pattern allows me to separate my concerns and focus on one part of the application at a time.
Model
I created a model class to hold the button flag and the two BufferedImages. This is the class where you would read the resources.
You can add the JFrame icon back to this class.
Model classes are plain Java getter/setter classes.
View
All Swing applications must start with a call to the SwingUtilities invokeLater method. This method ensures that the Swing components are created and executed on the Event Dispatch Thread.
Class names are written in camel case and start with an upper case character. Method names are written in camel case and start with a lower case character. Field names follow the same rules as method names.
I separated the creation of the JFrame from the creation of the JPanels. This helps me to separate my concerns and makes it much easier to visually verify whether or not the code is correct. Aim to write short methods that do one thing and do it well.
You have to manually draw a border on a graphic JPanel. I added the code to your paintComponent method to paint a partial border.
Your paintComponent method should paint. Period. Nothing else. It must also start with a call to the super.paintComponent method to maintain the Swing paint chain.
I changed your JLabel in the right JPanel to a JTextArea. A JTextArea allows for longer messages to word wrap on multiple lines and not make your JFrame change size.
Controller
Your JButton controller classes were fine, except for the class names.
Code
Here's the complete runnable code. I made all the additional classes inner classes so I could post the code in one block.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class DrawingProject implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new DrawingProject());
}
private final DrawingModel model;
private GraphicPanel graphicPanel;
private JTextArea textArea;
public DrawingProject() {
this.model = new DrawingModel();
}
#Override
public void run() {
JFrame frame = new JFrame("Drawing Project");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
graphicPanel = new GraphicPanel(model);
frame.add(createButtonPanel(), BorderLayout.WEST);
frame.add(graphicPanel, BorderLayout.CENTER);
frame.add(createTextPanel(), BorderLayout.EAST);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
panel.setBackground(Color.orange);
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 3));
JButton buttonOne = new JButton("Button number 1");
buttonOne.addActionListener(new ButtonOneListener());
panel.add(buttonOne);
JButton buttonTwo = new JButton("Button number 2");
buttonTwo.addActionListener(new ButtonTwoListener());
panel.add(buttonTwo);
return panel;
}
private JPanel createTextPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 3));
JLabel popeLabelTitle = new JLabel("What does the label say?");
popeLabelTitle.setFont(new Font(Font.MONOSPACED, Font.BOLD, 24));
panel.add(popeLabelTitle, BorderLayout.NORTH);
textArea = new JTextArea(4, 30);
textArea.setEditable(false);
textArea.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 20));
textArea.setText("Default label");
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
panel.add(textArea, BorderLayout.CENTER);
return panel;
}
public class GraphicPanel extends JPanel {
private static final long serialVersionUID = 1L;
private final DrawingModel model;
public GraphicPanel(DrawingModel model) {
this.model = model;
this.setPreferredSize(new Dimension(640, 480));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Paint border
int width = getWidth();
int height = getHeight();
int lineThickness = 3;
g.setColor(Color.BLACK);
g.fillRect(0, 0, width, height);
g.setColor(Color.YELLOW);
g.fillRect(0, lineThickness, width, height - 2 * lineThickness);
switch (model.getPainter()) {
case 0:
paintSampleText(g);
break;
case 1:
paintSampleImage(g);
break;
}
}
private void paintSampleText(Graphics g) {
BufferedImage image = model.getSampleText();
int x = (getWidth() - image.getWidth()) / 2;
int y = (getHeight() - image.getHeight()) / 2;
g.drawImage(image, x, y, this);
}
private void paintSampleImage(Graphics g) {
BufferedImage image = model.getSampleImage();
int x = (int) ((Math.random() * getWidth()) - image.getWidth());
int y = (int) ((Math.random() * getHeight()) - image.getHeight());
g.drawImage(image, x, y, this);
}
}
public class ButtonOneListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
textArea.setText("Reaction to button number 1: change of label.");
model.setPainter(0);
graphicPanel.repaint();
}
}
public class ButtonTwoListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
textArea.setText("Reaction to button number 2: change of label + "
+ "drawing images over gPanel.");
model.setPainter(1);
graphicPanel.repaint();
}
}
public class DrawingModel {
private int painter;
private final BufferedImage sampleText;
private final BufferedImage sampleImage;
public DrawingModel() {
this.painter = 0;
this.sampleText = createBufferedImage(Color.BLUE);
this.sampleImage = createBufferedImage(Color.MAGENTA);
}
private BufferedImage createBufferedImage(Color color) {
BufferedImage image = new BufferedImage(64, 64,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.setColor(color);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
g.dispose();
return image;
}
public int getPainter() {
return painter;
}
public void setPainter(int painter) {
this.painter = painter;
}
public BufferedImage getSampleText() {
return sampleText;
}
public BufferedImage getSampleImage() {
return sampleImage;
}
}
}
Update
In order to paint multiple images, you have to save the origin of the images in a List. I've modified the application model to hold a List of origin Point instances. I also corrected the code to create a random point.
Here's the GUI with multiple images.
Here's the modified code
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class DrawingProject implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new DrawingProject());
}
private final DrawingModel model;
private GraphicPanel graphicPanel;
private JTextArea textArea;
public DrawingProject() {
this.model = new DrawingModel();
}
#Override
public void run() {
JFrame frame = new JFrame("Drawing Project");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
graphicPanel = new GraphicPanel(model);
frame.add(createButtonPanel(), BorderLayout.WEST);
frame.add(graphicPanel, BorderLayout.CENTER);
frame.add(createTextPanel(), BorderLayout.EAST);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
panel.setBackground(Color.orange);
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 3));
JButton buttonOne = new JButton("Button number 1");
buttonOne.addActionListener(new ButtonOneListener());
panel.add(buttonOne);
JButton buttonTwo = new JButton("Button number 2");
buttonTwo.addActionListener(new ButtonTwoListener());
panel.add(buttonTwo);
return panel;
}
private JPanel createTextPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 3));
JLabel popeLabelTitle = new JLabel("What does the label say?");
popeLabelTitle.setFont(new Font(Font.MONOSPACED, Font.BOLD, 24));
panel.add(popeLabelTitle, BorderLayout.NORTH);
textArea = new JTextArea(4, 30);
textArea.setEditable(false);
textArea.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 20));
textArea.setText("Default label");
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
panel.add(textArea, BorderLayout.CENTER);
return panel;
}
public class GraphicPanel extends JPanel {
private static final long serialVersionUID = 1L;
private final DrawingModel model;
public GraphicPanel(DrawingModel model) {
this.model = model;
this.setPreferredSize(new Dimension(640, 480));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
paintMyBorder(g);
if (model.getPainter() == 1) {
createSampleImage(g);
}
paintSampleText(g);
BufferedImage image = model.getSampleImage();
List<Point> origin = model.getImageOrigin();
for (Point point : origin) {
g.drawImage(image, point.x, point.y, this);
}
}
private void paintMyBorder(Graphics g) {
int width = getWidth();
int height = getHeight();
int lineThickness = 3;
g.setColor(Color.BLACK);
g.fillRect(0, 0, width, height);
g.setColor(Color.YELLOW);
g.fillRect(0, lineThickness, width, height - 2 * lineThickness);
}
private void paintSampleText(Graphics g) {
BufferedImage image = model.getSampleText();
int x = (getWidth() - image.getWidth()) / 2;
int y = (getHeight() - image.getHeight()) / 2;
g.drawImage(image, x, y, this);
}
private void createSampleImage(Graphics g) {
BufferedImage image = model.getSampleImage();
int x = (int) (Math.random() * (getWidth() - image.getWidth()));
int y = (int) (Math.random() * (getHeight() - image.getHeight()));
model.addNewImageOrigin(new Point(x, y));
}
}
public class ButtonOneListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
textArea.setText("Reaction to button number 1: change of label.");
model.setPainter(0);
graphicPanel.repaint();
}
}
public class ButtonTwoListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
textArea.setText("Reaction to button number 2: change of label + "
+ "drawing images over gPanel.");
model.setPainter(1);
graphicPanel.repaint();
}
}
public class DrawingModel {
private int painter;
private final BufferedImage sampleText;
private final BufferedImage sampleImage;
private final List<Point> imageOrigin;
public DrawingModel() {
this.painter = 0;
this.sampleText = createBufferedImage(Color.BLUE);
this.sampleImage = createBufferedImage(Color.MAGENTA);
this.imageOrigin = new ArrayList<>();
}
private BufferedImage createBufferedImage(Color color) {
BufferedImage image = new BufferedImage(64, 64,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.setColor(color);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
g.dispose();
return image;
}
public void addNewImageOrigin(Point point) {
this.imageOrigin.add(point);
}
public int getPainter() {
return painter;
}
public void setPainter(int painter) {
this.painter = painter;
}
public BufferedImage getSampleText() {
return sampleText;
}
public BufferedImage getSampleImage() {
return sampleImage;
}
public List<Point> getImageOrigin() {
return imageOrigin;
}
}
}

paint() doesn't work after panel and frame was added

I am making kind of my paint that creates shapes, it worked fine until I added layers(panel and frame), now the shapes aren't visible on button press I assume it is under the layers?i tried using paintComponent and revalidate etc and still couldn't get it to appear
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Main2 extends JPanel implements ActionListener {
private static Square mySquare;
private static Circle myCircle;
private static Color myColor;
public boolean SquareCheck;
public boolean CircleCheck;
JButton buttonSquare;
JButton buttonCircle;
JFrame frame;
JPanel panel;
public void paint(Graphics g) {
if (SquareCheck) {
g.setColor(myColor);
g.fillRect(mySquare.x, mySquare.y, mySquare.width, mySquare.length);
} else if (CircleCheck) {
g.setColor(myColor);
g.fillOval(myCircle.x, myCircle.y, myCircle.width, myCircle.length);
}
}
public void start() {
frame = new JFrame();
panel = new JPanel();
//setLayout(new BorderLayout());
buttonSquare = new JButton("■");
buttonCircle = new JButton("●");
buttonSquare.setPreferredSize(new Dimension(200, 20));
buttonCircle.setPreferredSize(new Dimension(200, 20));
buttonCircle.addActionListener(this);
buttonSquare.addActionListener(this);
//add(buttonCircle, BorderLayout.NORTH);
//add(buttonSquare, BorderLayout.SOUTH);
JToggleButton red = new JToggleButton();
panel.add(buttonCircle);
panel.add(buttonSquare);
frame.add(panel);
frame.setSize(500, 500);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == buttonSquare) {
SquareCheck = true;
} else if (e.getSource() == buttonCircle) {
CircleCheck = true;
}
repaint();
}
public static void main(String[] args) {
mySquare = new Square(30, 50, 50, 50);
myCircle = new Circle(60, 100, 50, 50);
myColor = Color.red;
Main2 x = new Main2();
x.start();
}
}
Basiclly the buttons changes the boolean then the repaint is called and based on the boolean it draws either a cirlce or a square,the code worked before adding frame and panel

Your paint method is a method of the Main2 class, but you never add a Main2 instance to the JFrame or to any component that goes into the JFrame, and so the Main2 instance will never be displayed, and the Swing painting manager will never call its paint method.
For starters, get rid of this variable, panel = new JPanel(); and every place you use panel, substitute this. This way you'll be working with a correct Main2 instance and adding it to the GUI.
Other issues:
You need to call the super's equivalent painting method in your override on its first line
Override paintComponent, not paint, and yes call super.paintComponenet(g); in this override
You will want to learn and use Java naming conventions. Variable names should all begin with a lower letter while class names with an upper case letter. Learning this and following this will allow us to better understand your code, and would allow you to better understand the code of others.
For safety's sake, add the #Override annotation above any method that you think may be overriding a parent method (such as paint), to make sure that you are doing it correctly.
For example:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
#SuppressWarnings("serial")
public class Main2 extends JPanel implements ActionListener {
private static Square mySquare;
private static Circle myCircle;
private static Color myColor;
private JToggleButton buttonSquare;
private JToggleButton buttonCircle;
JFrame frame;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (buttonSquare.isSelected()) {
g.setColor(myColor);
g.fillRect(mySquare.x, mySquare.y, mySquare.width, mySquare.length);
}
if (buttonCircle.isSelected()) {
g.setColor(myColor);
g.fillOval(myCircle.x, myCircle.y, myCircle.width, myCircle.length);
}
}
public Main2() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
buttonSquare = new JToggleButton("■");
buttonCircle = new JToggleButton("●");
buttonCircle.addActionListener(this);
buttonSquare.addActionListener(this);
this.add(buttonCircle);
this.add(buttonSquare);
frame.add(this);
frame.setSize(500, 500);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
repaint();
}
public static void main(String[] args) {
mySquare = new Square(30, 50, 50, 50);
myCircle = new Circle(60, 100, 50, 50);
myColor = Color.red;
new Main2();
}
}
class MyShape {
public int x, y, width, length;
public MyShape(int x, int y, int width, int length) {
this.x = x;
this.y = y;
this.width = width;
this.length = length;
}
}

Paint component disappear after resizing window or use scrollbar

I write a program to draw 50 rectangles after clicking OK button. But I don't uderstand why it disappears after resizing window, using scrollbar or clicking on OK again.
Here's my code (I have two classes: drawingPanel and Main)
drawingPanel.java:
import javax.swing.*;
import java.awt.*;
public class drawingPanel extends JPanel
{
public boolean drawIt = false;
public int x = 140,y = 0;
public void paintIt()
{
drawIt = true;
repaint();
}
public void paintComponent(Graphics g)
{
if (drawIt == true)
{
super.paintComponent(g);
for (int i = 1; i <= 50; i++)
{
g.fillRect(x, y, 50, 50);
y += 70;
}
}
}
}
Main.java:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame
{
private drawingPanel draw = new drawingPanel();
private JPanel controlPanel = new JPanel();
private JButton ok = new JButton("OK");
private JScrollPane scroll = new JScrollPane(draw);
public Main()
{
setSize(500,500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Demo");
setLayout(new BorderLayout());
controlPanel.setLayout(new FlowLayout());
controlPanel.add(ok);
ok.addActionListener(new okListener());
draw.setPreferredSize(new Dimension(100,1000));
add(controlPanel, BorderLayout.NORTH);
add(scroll,BorderLayout.CENTER);
setVisible(true);
}
private class okListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
draw.paintIt();
}
}
public static void main(String[] args)
{
new Main();
}
}
Please help me, thanks in advance.

Re-initialize x and y fields within your paint component method like so that they won't keep increasing out of view each time the JPanel is drawn:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); // move this here
if (drawIt) {
x = 140; // add these guys
y = 0;
for (int i = 1; i <= 50; i++) {
// .... etc....
and things should draw OK.
Other minor issues not related to your question:
The super's painting method should always be called, so pull that out of the if block.
Rename your drawingPanel class to be DrawingPanel so that it conforms to Java conventions.
Better to change if (drawIt == true) { to the more simple if (drawIt) {
Minor quibble: paintComponent should be protected, not public.

Transfer value to an external method in Java

So I have a program that's meant to update a thermometer bar (using drawRect) dynamically based on the position of a JSlider. What I'm trying to do is to pass that value to an external method so I can use it to update the size of the rectangle. I'm a VB guy so I'm having trouble figuring out how to do it.
Here's my main class:
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
public class ThermoProject extends JApplet
{
JSlider mySlider;
JPanel sliderPanel;
JPanel northernPanel = new NorthPanel();
JLabel printLabel = new JLabel("");
static int fillSize = 0;
int topSize = 100;
public void init() //init is the "main" for an applet
{
buildSliderPanel();
sliderPanel.setBackground(Color.gray);
add(northernPanel, BorderLayout.NORTH); //separate class
add(printLabel, BorderLayout.WEST); //add label to top
add(sliderPanel, BorderLayout.SOUTH); //add the panel to the south of the borderLayout
}
private void buildSliderPanel()
{
sliderPanel = new JPanel();
//JSlider(direction, beginning, end, initial location)
mySlider = new JSlider(JSlider.HORIZONTAL, 0, 100, 0);
mySlider.setMajorTickSpacing(10);
mySlider.setPaintTicks(true);
mySlider.setPaintLabels(true);
mySlider.setSnapToTicks(true);
//add listener
mySlider.addChangeListener(new SliderListener());
//add to panel
sliderPanel.add(mySlider);
}
public class SliderListener implements ChangeListener
{
public void stateChanged(ChangeEvent e)
{
//change when slider is moved
updateThermo(mySlider.getValue());
//topSize = 100 - fillSize;
//drawRect(x, y, width, height)
//fillRect(x, y, width, height)
repaint();
}
}
}
And here's my subclass, which is mostly used to build a separate JPanel.
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
public class NorthPanel extends JPanel
{
JPanel theNorthernPanel;
int fillSize = 0;
public void paint(Graphics g)
{
//drawRect() and fillRect() args are x, y, width, height
g.drawRect(90, 90, 200, 30);
g.setColor(Color.red);
g.fillRect(90, 90, fillSize, 30);
}
public NorthPanel()
{
JPanel theNorthernPanel = new JPanel();
setPreferredSize(new Dimension(200, 200));
JLabel printLabel = new JLabel(String.valueOf(fillSize));
theNorthernPanel.add(printLabel);
add(theNorthernPanel);
}
public void updateThermo(int temperature)
{
fillSize = temperature;
}
}

try this:
NorthPanel northernPanel = new NorthPanel(); // to declare
and then,
northernPanel.updateThermo(mySlider.getValue()); //to call

You paint code is broken, start by taking a look at Painting in AWT and Swing and Performing Custom Painting for more details.
To call a method, you need a reference to the instance of the class you want to call...
Start by changing
JPanel northernPanel = new NorthPanel();
to
NorthPanel northernPanel = new NorthPanel();
And then use it to call the method....
northernPanel.updateThermo(mySlider.getValue());

I belive that you should change the content of the SliderListener to:
public class SliderListener implements ChangeListener
{
public void stateChanged(ChangeEvent e)
{
//change when slider is moved
((NorthPanel)northernPanel).updateThermo(mySlider.getValue());
//topSize = 100 - fillSize;
//drawRect(x, y, width, height)
//fillRect(x, y, width, height)
northernPanel.repaint();
}
}
In the code snippet you presented you're trying to invoke a member of ThermoProject.
Also take notion of casting to NorthPanel which is necessary, because you declared northernPanel as a more general type:
JPanel northernPanel = new NorthPanel();

actionPerformed skip a step

I want everytime i click on the button "bouton" to execute the function
boutonPane.Panel2(h, ....) which is supposed to display h circles. So i want 2 then 3 then 4, then 5... circles.
The problem is that it is not displaying the step with number 4. I see the function is called in the console but on the screen it does really 2, (press button) 3, (press button) 5, (press button)9. I dont see 4. I dont see 6,7,8.. Could you tell me what is the problem please? Here is the code:
public class Window extends JFrame implements ActionListener {
int lg = 1000; int lrg = 700;
int h = 2;
Panel b = new Panel();
private JButton btn = new JButton("Start");
JButton bouton = new JButton();
private JPanel container = new JPanel();
public Window(){
this.setTitle("Animation");
this.setSize(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
btn.addActionListener(this);
top.add(btn);
container.add(top);
this.setContentPane(container);
this.setVisible(true);
}
public void Window2()
{
System.out.println("windows2");
this.setTitle("ADHD");
this.setSize(lg, lrg);
this.setLocationRelativeTo(null);
bouton.addActionListener(this);
if(h<11)
{
Panel boutonPane = new Panel();
boutonPane.Panel2(h, Color.BLUE ,lg, lrg, this.getGraphics());
System.out.println("draw"+h);
boutonPane.add(bouton);
this.add(boutonPane);
this.setContentPane(boutonPane);
this.revalidate();
this.repaint();
}
this.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if((JButton)e.getSource()==btn)
{
System.out.println("pressed0");
Window2();
}
if((JButton)e.getSource()==bouton)
{
h++;
System.out.println("pressed"+h);
Window2();
}
}
}
Here is a the Panel class:
public class Panel extends JPanel
{
int m;
int i=1;
int a=0, b=0, tremp=0;
Color cc;
int lgi, lrgi;
int [] ta;
int [] tb;
Graphics gi;
int u=0;
Panel()
{
}
public void Panel2(int n, Color c, int lg, int lrg, Graphics g){
m=n;
cc=c;
gi=g;
lgi=lg;
lrgi=lrg;
ta = new int [n]; ta[0]=0;
tb = new int [n]; tb[0]=0;
}
public void paintComponent( final Graphics gr){
gr.setColor(Color.red);
for(int it=0; it<m;it++)
{
ta[it]=100*it;
tb[it]=100*it;
gr.fillOval(ta[it],tb[it], 150, 150);
}
}
}

"But would you have an idea of another, correct, way to do what I want please?"
You should only have one panel for the circles. There's absolutely no need to keep creating new panel.
Use a List for Ellipse2D objects. Just loop through them in the paintComponent method.
When you want to add a new circle, just add a new Ellipse2D object to the List and call repaint()
Here's an example.
NOTE Accept Gijs Overvliet's answer, as his was the one that answered your problem. I just wanted to share some insight.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class EllipseList extends JPanel {
private static final int D_W = 700;
private static final int D_H = 500;
private static final int CIRCLE_SIZE = 50;
private List<Ellipse2D> circles;
private double x = 0;
private double y = 0;
private CirclePanel circlePanel = new CirclePanel();
public EllipseList() {
circles = new ArrayList<>();
JButton jbtAdd = createButton();
JFrame frame = new JFrame();
frame.add(jbtAdd, BorderLayout.NORTH);
frame.add(circlePanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JButton createButton() {
JButton button = new JButton("Add");
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
circles.add(new Ellipse2D.Double(x, y, CIRCLE_SIZE, CIRCLE_SIZE));
x += CIRCLE_SIZE * 0.75;
y += CIRCLE_SIZE * 0.75;
circlePanel.repaint();
}
});
return button;
}
public class CirclePanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setPaint(Color.RED);
for (Ellipse2D circle : circles) {
g2.fill(circle);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(D_W, D_H);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new EllipseList();
}
});
}
}

Try this:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Window extends JFrame implements ActionListener
{
int lg = 1000;
int lrg = 700;
int h = 2;
Panel b = new Panel();
private JButton btn = new JButton("Start");
JButton bouton = new JButton();
private JPanel container = new JPanel();
Panel boutonPane = new Panel();
public Window()
{
this.setTitle("Animation");
this.setSize(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
btn.addActionListener(this);
top.add(btn);
container.add(top);
this.setContentPane(container);
this.setVisible(true);
}
public void Window2()
{
System.out.println("windows2");
this.setTitle("ADHD");
this.setSize(lg, lrg);
this.setLocationRelativeTo(null);
bouton.addActionListener(this);
if (h < 11)
{
boutonPane.Panel2(h, Color.BLUE, lg, lrg, this.getGraphics());
System.out.println("draw" + h);
boutonPane.add(bouton);
this.add(boutonPane);
this.setContentPane(boutonPane);
updateWindow2();
}
this.setVisible(true);
}
public void updateWindow2()
{
boutonPane.Panel2(h, Color.BLUE, lg, lrg, this.getGraphics());
this.revalidate();
this.repaint();
}
public void actionPerformed(ActionEvent e)
{
if ((JButton) e.getSource() == btn)
{
System.out.println("pressed0");
Window2();
}
if ((JButton) e.getSource() == bouton)
{
h++;
System.out.println("pressed" + h);
updateWindow2();
}
}
public static void main(String[] args)
{
Test t = new Test();
}
}
What you did wrong was adding a new BoutonPane every time you clicked the button. The next time you clicked the button, you didn't click ONE button, but TWO buttons, adding two more boutonPanes, and two more buttons. This multiplies very quickly.
What I did was the following:
make boutonPane a class member variable
call window2() only once
create a method updateWindow2() for updating the circles. Call that method from window2() and actionPerformed().