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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;
}
}
}

Cant paint on JFrame

I am having a problem drawing a JLabel on my JFrame. I already did that in another project and it was working properly, but i messed up somewhere this time and cant draw anymore. Here is my Code:
Board:
import javax.swing.*;
import java.awt.*;
public class Board extends JPanel {
public Board() {
initBoard();
}
private void initBoard() {
setPreferredSize(new Dimension(Frame.GAME_WIDTH, Frame.GAME_HEIGHT));
setMinimumSize(new Dimension(Frame.GAME_WIDTH, Frame.GAME_HEIGHT));
setMaximumSize(new Dimension(Frame.GAME_WIDTH, Frame.GAME_HEIGHT));
setBackground(Color.GRAY);
setDoubleBuffered(true);
}
}
Frame:
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;
import java.io.File;
import java.io.IOException;
public class Frame extends JFrame {
public static final int GAME_WIDTH = 800;
public static final int GAME_HEIGHT = 600;
private final String title = "title here";
private Image backgroundIMG;
public Frame() {
initUI();
}
private void initUI() {
add(new Board());
pack();
setTitle(title);
setSize(GAME_WIDTH, GAME_HEIGHT);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setResizable(false);
setLayout(null);
/*
* set background image
*/
/*try {
this.backgroundIMG = ImageIO.read(new File("src/to/image"));
} catch (IOException e) {
e.printStackTrace();
}*/
Border emptyBorder = BorderFactory.createEmptyBorder();
int titleWidth = 270;
int titleHeight = 55;
int titleX = 24;
int titleY = 30;
int titleSize = 47;
String titleFont = "Ravie";
/*
* Customize the startscreen
*/
JLabel title = new JLabel("text");
title.setBounds(0, 0, titleWidth, titleHeight);
title.setFont(new Font(titleFont, Font.BOLD, titleSize));
title.setForeground(new Color(251,102,8));
title.setLocation(titleX, titleY);
add(title);
System.out.println("title should be printed");
}
}
Launcher:
import java.awt.*;
public class Launcher {
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
Frame main = new Frame();
main.setVisible(true);
});
}
}
When i start the program, the Frame is loading up but does not display the JLabel. Its also printing "title should be printed" on the console. I did some research already but wasnt able to find anything that helped me. Maybe its just a trivial error and someone can help me out real quick.
Thanks in advance

Getting past all the, "interesting" stuff for moment, you're basic problem comes down to this...
add(new Board());
//...
add(title);
Java/Swing paint's it's component in LIFO order, so the last component added, is the first component painted.
Probably the most logical fix is to add title to the Board, but you might want to fix a couple of other issues first...
Avoid extending from top level containers like JFrame. Lots of reasons, but mostly, you're not adding new functionality to the class and it's locking you into a single use case which can be better managed through other means/components
Avoid setPreferred/Minimum/MaximumSize. These are more trouble then they are worth. Instead, as required, override getPreferredSize
setDoubleBuffered(true); is pointless, as Swing components are double buffered by default
Avoid null layouts, seriously, this is the number one cause of most of the issues people post about on SO. The layout management API is there for a reason, learn to make use of it.
If we take all that into account, you might end up within something more like...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Image;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) {
new Test();
}
private final String title = "title here";
public Test() {
EventQueue.invokeLater(() -> {
JFrame main = new JFrame(title);
main.add(new MainPane());
main.pack();
main.setLocationRelativeTo(null);
main.setVisible(true);
});
}
public static final int GAME_WIDTH = 800;
public static final int GAME_HEIGHT = 600;
public static class MainPane extends JPanel {
private Image backgroundIMG;
public MainPane() {
setLayout(new BorderLayout());
setBackground(Color.GRAY);
add(new Board());
String titleFont = "Ravie";
int titleSize = 47;
JLabel title = new JLabel("text");
title.setHorizontalAlignment(JLabel.CENTER);
title.setFont(new Font(titleFont, Font.BOLD, titleSize));
title.setForeground(new Color(251, 102, 8));
add(title, BorderLayout.NORTH);
}
}
public static class Board extends JPanel {
public Board() {
initBoard();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(GAME_WIDTH, GAME_HEIGHT);
}
private void initBoard() {
setBackground(Color.GRAY);
}
}
}

Clicking a button within a JFrame passes an data to a JPanel

I have a Jframe with two buttons: '1' and '2'. Clicking the button '1' should display the capital letter A in the JPanel.
Code fore my JFrame:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class DrawFrame extends JFrame{
private final int WIDTH = 500;
private final int HEIGHT = 300;
private JButton number1;
private JButton number2;
private JPanel numberPanel;
private DrawPanel graphicsPanel;
public DrawFrame()
{
createSelectionPanel();
createGraphicsPanel();
this.setSize(WIDTH, HEIGHT);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
private void createSelectionPanel()
{
numberPanel = new JPanel();
number1 = new JButton("1");
number2 = new JButton("2");
numberPanel.setLayout(new GridLayout(2,2));
numberPanel.add(number1);
numberPanel.add(number2);
this.add(numberPanel, BorderLayout.WEST);
}
private void createGraphicsPanel()
{
//instantiate drawing panel
graphicsPanel = new DrawPanel();
//add drawing panel to right
add(graphicsPanel);
}
private class Number1ButtonListener implements ActionListener {
public void actionPerformed (ActionEvent event) {
Number number = new Number();
number.setNumber('A');
}
}
//creates a drawing frame
public static void main(String[] args)
{
DrawFrame draw = new DrawFrame();
}
}
Code for my JPanel
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
public class DrawPanel extends JPanel{
public Coordinates current;
public DrawPanel(){
//nothing drawn initially
current = null;
//set white background for drawing panel
setBackground(Color.WHITE);
//add mouse listeners
MouseHandler mouseHandler = new MouseHandler();
this.addMouseListener(mouseHandler);
this.addMouseMotionListener(mouseHandler);
}
public void paint(Graphics g){
super.paint(g);
if(current!=null){
I want to replace "A" with number.getNumber()
g.drawString("A", current.getX(), current.getY());
}
}
//class to handle all mouse events
private class MouseHandler extends MouseAdapter implements MouseMotionListener
{
public void mousePressed(MouseEvent event)
{
current = new Coordinates(event.getX(), event.getY());
}
public void mouseReleased(MouseEvent event)
{
repaint();
}
}
}
I'm not sure if this is possible. So sorry if I am mistaken in my logic. Please provide an alternate way for me to approach this problem. Appreciate any guidance.
Thanks!

The Coordinates and Number classes weren't included, so I had to modify the code somewhat.
Here's the GUI I created.
The first thing I did was create a model class for the GUI. By creating a model class, I could make the display string and the drawing coordinate available to the view and the controller classes. This is a simple example of the model / view / controller pattern.
package com.ggl.drawing;
import java.awt.Point;
public class GUIModel {
private String displayString;
private Point coordinate;
public GUIModel(String displayString) {
this.displayString = displayString;
}
public Point getCoordinate() {
return coordinate;
}
public void setCoordinate(int x, int y) {
this.coordinate = new Point(x, y);
}
public void setCoordinate(Point coordinate) {
this.coordinate = coordinate;
}
public void setDisplayString(String displayString) {
this.displayString = displayString;
}
public String getDisplayString() {
return displayString;
}
}
Now that we have a model, lets look at the DrawFrame class.
package com.ggl.drawing;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class DrawFrame implements Runnable {
private final int WIDTH = 500;
private final int HEIGHT = 300;
private JFrame frame;
private GUIModel model;
public DrawFrame() {
this.model = new GUIModel("A");
}
#Override
public void run() {
frame = new JFrame("Draw Letters");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createSelectionPanel(), BorderLayout.WEST);
frame.add(new DrawPanel(WIDTH, HEIGHT, model), BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
private JPanel createSelectionPanel() {
JPanel numberPanel = new JPanel();
ButtonListener listener = new ButtonListener();
JButton number1 = new JButton("A");
number1.addActionListener(listener);
JButton number2 = new JButton("B");
number2.addActionListener(listener);
numberPanel.setLayout(new GridLayout(0, 2));
numberPanel.add(number1);
numberPanel.add(number2);
return numberPanel;
}
private class ButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
model.setDisplayString(event.getActionCommand());
}
}
// creates a drawing frame
public static void main(String[] args) {
SwingUtilities.invokeLater(new DrawFrame());
}
}
I started the Java Swing application on the Event Dispatch thread with the call to the SwingUtilities invokeLater method.
I separated the JFrame construction from the 2 JPanels construction. I used a JFrame, rather than extend a JFrame. The only time you should extend any Java class is if you want to override one or more of the class methods.
I used the same ButtonListener for both JButtons. I'm guessing what you want, but I drew either an "A" or a "B", depending on which button you left clicked.
Let's look at the DrawPanel class.
package com.ggl.drawing;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JPanel;
public class DrawPanel extends JPanel {
private static final long serialVersionUID = 3443814601865936618L;
private GUIModel model;
public DrawPanel(int width, int height, GUIModel model) {
this.setPreferredSize(new Dimension(width, height));
this.model = model;
// add mouse listeners
MouseHandler mouseHandler = new MouseHandler();
this.addMouseListener(mouseHandler);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (model.getCoordinate() != null) {
Point p = model.getCoordinate();
Font font = g.getFont().deriveFont(48F);
g.setFont(font);
g.drawString(model.getDisplayString(), p.x, p.y);
}
}
// class to handle all mouse events
private class MouseHandler extends MouseAdapter {
#Override
public void mousePressed(MouseEvent event) {
model.setCoordinate(event.getPoint());
}
#Override
public void mouseReleased(MouseEvent event) {
DrawPanel.this.repaint();
}
}
}
The major change I made in this class was to use the paintComponent method, rather than the paint method. The paintComponent method is the correct method to override.
I set the size of the drawing panel in the DrawPanel constructor. It's much better to let Swing figure out the size of the JFrame. That's what the pack method in the DrawFrame run method does.
I increased the font size so you can see the drawn letter better.
I removed the mouse motion listener code, as it wasn't needed.
I hope this was helpful to you.

OK, all I know so far is that you want the text displayed in a JPanel to change if a button is pressed. If so, then your code looks to be way too complex for the job. Suggestions include:
Give the DrawingPanel a setter method, say, setText(String text), that allows outside classes to change the text that it displays.
Within that method, set a field of DrawingPanel, say called text, and call repaint().
Override DrawingPanel's paintComponent not its paint method, and call the super's method within your override.
Within the paintComponent method, call drawString to draw the String held by the text field, if the field is not null.
Give your buttons ActionListeners or AbstractActions that call the DrawingPanel's setText(...) method, setting the text to be displayed.
For example:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class DrawAorB extends JPanel {
private DrawingPanel drawingPanel = new DrawingPanel();
public DrawAorB() {
JPanel btnPanel = new JPanel(new GridLayout(1, 0, 5, 5));
btnPanel.add(new JButton(new ButtonAction("A")));
btnPanel.add(new JButton(new ButtonAction("B")));
setLayout(new BorderLayout());
add(drawingPanel, BorderLayout.CENTER);
add(btnPanel, BorderLayout.PAGE_END);
}
private class ButtonAction extends AbstractAction {
public ButtonAction(String name) {
super(name);
}
#Override
public void actionPerformed(ActionEvent e) {
String text = e.getActionCommand();
drawingPanel.setText(text);
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("DrawAorB");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new DrawAorB());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class DrawingPanel extends JPanel {
private static final int PREF_W = 200;
private static final int PREF_H = PREF_W;
private String text = null;
public void setText(String text) {
this.text = text; // set the JPanel's text
repaint(); // and draw it
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (text != null) {
int x = getWidth() / 2;
int y = getHeight() / 2;
// use FontMetrics if you want to center text better
g.drawString(text, x, y);
}
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
}
Even simpler, easier, and probably better would be to display the text within a JLabel as it's much easier to center this text.

Program is not painting the GUI when called

I am a high school student trying to teach myself GUI basics. The program I am trying to write would take two numbers from the user and then plot those two numbers in a graph. The user can also enter more points if he or she likes. The problem I am having is that when I press the button that opens the GUI that should be the graph, the GUI appears but it is blank. I think there is an issue with the paint method and the way that is being set up and called but I am not sure. Thanks in advance for any advice or help.
This is the class that creates the graph GUI:
package dataGraph;
import javax.swing.*;
import java.awt.*;
import javax.swing.JFrame;
import java.awt.Graphics;
import java.awt.Graphics2D;
public class graphGUI extends JFrame {
//public Graphics2D g2;
public graphGUI() {
setTitle("Data Graph");
setSize(500, 500);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
setVisible(true);
}
public void paint(Graphics g) {
super.paintComponents(g);
g.drawLine(40, 425, 450, 425);
g.drawLine(40, 425, 40, 70);
g.drawString("Graph", 20, 20);
// g2.draw
g.drawLine(50, 50, 50, 50);
for(int i = 0; i < dataEntryGUI.x.size(); i++){
g.drawOval(Integer.parseInt(dataEntryGUI.x.get(i)),
Integer.parseInt(dataEntryGUI.y.get(i)),5,5);
}
}
}
This is the class that creates the GUI for data entry and has the action listener that allows the user to add more "points" and then "graph" them:
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JFrame;
public class dataEntryGUI extends JFrame implements ActionListener {
public static ArrayList<String> x;
public static ArrayList<String> y;
private Button btnAdd;
private Button btnGraph;
private Label lbl;
private Label lbl2;
private TextField xInt;
private TextField yInt;
public dataEntryGUI() {
setTitle("Data entry");
setSize(250, 250);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
lbl = new Label("x");
lbl2 = new Label("y");
// text fields
xInt = new TextField();
yInt = new TextField();
x = new ArrayList<String>();
y = new ArrayList<String>();
// add button
btnAdd = new Button("Add another");
// btnAdd.setPreferredSize(new Dimension(70,30));
btnAdd.addActionListener(this);
btnGraph = new Button("Make Graph");
btnGraph.addActionListener(this);
add(lbl);
add(xInt);
add(lbl2);
add(yInt);
add(btnAdd);
add(btnGraph);
setLayout(new FlowLayout());
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
// System.out.println("boogers");
if (e.getSource() == btnAdd) {
//xInt.getText();
x.add(xInt.getText());
y.add(yInt.getText());
xInt.setText("");
yInt.setText("");
} else {
graphGUI graph = new graphGUI();
graph.repaint();
}
}
}
And this is the main method:
package dataGraph;
public class dataGraphMain {
public static void main(String[] args) {
dataEntryGUI gui = new dataEntryGUI();
//graphGUI gui2 = new graphGUI();
}
}

public void paint(Graphics g) {
super.paintComponents(g);
In general, whenever you override a method you should be invoking "super" on the method name you are overriding, not some other method. That is in this case you would invoke:
super.paint(g);
However, for custom painting you should NOT override the paint() method of a JFrame.
Instead you should override the paintComponent(...) method of a JPanel and then add the panel to the frame. Read the section from the Swing tutorial on Custom Painting for more information and examples.
I am a high school student trying to teach myself GUI basics.
Keep a link to the Table of Contents of the Swing tutorial handy for future reference as the tutorial covers the basics and more.

As mentioned by camickr, some refactoring should be done. Perhaps this will help.
First, you are trying to repaint the JFrame. This is not recommended. What you want to do is define a JPanel to work on and add it to the frame's pane content.
I refactored your code a bit, so that GraphGUI is now a JPanel, and not a JFrame. This way, you can use it as a component in any future JFrame you might create.
Second, I defined a function within DataEntryGUI that creates a new frame, which will hold the graph component and paint it. Here's the complete code:
Class GraphGUI
package dataGraph;
import javax.swing.*;
import java.awt.*;
import java.awt.Graphics;
public class graphGUI extends JPanel {
public GraphGUI() {
setBackground(Color.WHITE);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawLine(40, 425, 450, 425);
g.drawLine(40, 425, 40, 70);
g.drawString("Graph", 20, 20);
g.drawLine(50, 50, 50, 50);
for(int i = 0; i < dataEntryGUI.x.size(); i++){
g.drawOval(Integer.parseInt(dataEntryGUI.x.get(i)),
Integer.parseInt(dataEntryGUI.y.get(i)),5,5);
}
}
}
DataEntryGUI
package dataGraph;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JFrame;
public class DataEntryGUI extends JFrame implements ActionListener {
public static ArrayList<String> x; //This should be figured out by
public static ArrayList<String> y; //the OP. Encapsulation and
//decoupling is a different matter.
private Button btnAdd;
private Button btnGraph;
private Label lbl;
private Label lbl2;
private TextField xInt;
private TextField yInt;
public DataEntryGUI() {
setTitle("Data entry");
setSize(250, 250);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setResizable(false);
lbl = new Label("x");
lbl2 = new Label("y");
// text fields
xInt = new TextField();
yInt = new TextField();
x = new ArrayList<String>();
y = new ArrayList<String>();
// add button
btnAdd = new Button("Add another");
// btnAdd.setPreferredSize(new Dimension(70,30));
btnAdd.addActionListener(this);
btnGraph = new Button("Make Graph");
btnGraph.addActionListener(this);
add(lbl);
add(xInt);
add(lbl2);
add(yInt);
add(btnAdd);
add(btnGraph);
setLayout(new FlowLayout());
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
// System.out.println("boogers");
if (e.getSource() == btnAdd) {
//xInt.getText();
x.add(xInt.getText());
y.add(yInt.getText());
xInt.setText("");
yInt.setText("");
} else {
paintGraph();
}
}
private void paintGraph() {
JFrame graphFrame = new JFrame();
GraphGUI graph = new GraphGUI();
graphFrame.getContentPane().add(graph);
graphFrame.setTitle("Data Graph");
graphFrame.setSize(500, 500);
graphFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
graphFrame.setResizable(false);
graphFrame.setVisible(true);
}
}
This seems to exhibit the behavior you wanted. I have some thoughts/comments on how you pass your x,y data (and the fact that they are public and not private), but this is beyond the scope of what you needed here.

Show the line numbers when the JScrollBar is moved

In a linux text editor, Kate, there is this nice functionality that when I click and drag the scroll bar it shows the current line numbers that are currently in view in the text component.
My question is how can I add this function in Java to my scroll pane containing a JTextArea. Which component can I use to show this notification?

Apparently you can do this with a JPopupMenu:
I tried with this class because I knew it had the method show(Component, x, y). But it might be possible with other classes, or trying to implement whatever that method does yourself.
I put a couple of mouse listeners to the scrollBar and toyed a little with the values x, y in the show() call until I was satisfied with the position where it was being drawn at.
Full code:
import java.awt.Dimension;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPopupMenu;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class ScrollbarTest
{
private JScrollPane scrollPane;
private JScrollBar scrollBar;
private JPopupMenu popupMenu;
private JLabel popupLabel;
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new ScrollbarTest();
}
});
}
public ScrollbarTest()
{
JFrame frame = new JFrame("Test");
popupMenu = new JPopupMenu();
popupLabel = new JLabel();
popupMenu.add(popupLabel);
scrollPane = new JScrollPane(buildTestTextArea());
scrollBar = scrollPane.getVerticalScrollBar();
scrollBar.addMouseMotionListener(new PopUpMouseMotionListener());
scrollBar.addMouseListener(new PopUpMouseListener());
frame.add(scrollPane);
frame.setSize(new Dimension(400, 400));
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public JTextArea buildTestTextArea()
{
JTextArea textArea = new JTextArea();
StringBuilder builder = new StringBuilder();
for (int i = 0; i < 10000; ++i)
{
builder.append("X");
}
textArea.setText(builder.toString());
textArea.setLineWrap(true);
return textArea;
}
private class PopUpMouseMotionListener extends MouseMotionAdapter
{
#Override
public void mouseDragged(MouseEvent e)
{
double value = scrollBar.getValue();
double max = scrollBar.getMaximum() - scrollBar.getVisibleAmount();
double h = scrollBar.getHeight();
popupLabel.setText("" + (int) (100*value/max) + "%");
popupMenu.show(scrollPane, scrollBar.getX() - popupMenu.getWidth() - 2, (int) ((h - popupMenu.getHeight())*value/max));
}
}
private class PopUpMouseListener extends MouseAdapter
{
#Override
public void mouseReleased(MouseEvent e)
{
popupMenu.setVisible(false);
}
}
}