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java jlabel disappears in game loop

The goal here is to use jlabels with an image icon that contains a BufferedImage. Those jlabels can then be easily moved around with the mouse without having to go searching a ton of different BufferedImages on the screen to find out which one is being clicked on.
This is easy to do in a standard JFrame. I've been searching around here for an hour trying to figure out how to implement this in a game loop where a paintComponent is overridden.
import javax.swing.*;
import java.awt.*;
public class Main {
public Main() {
}
public static void main(String[] args) {
JFrame window = new JFrame();
GamePanel gamePanel = new GamePanel();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(true);
window.setLayout(new FlowLayout());
window.setTitle("FX Test");
window.add(gamePanel);
window.pack();
window.setLocationRelativeTo(null);
window.setVisible(true);
gamePanel.startGameThread();
}
}
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
public class GamePanel extends JPanel implements ActionListener {
private Timer gameLoopTimer;
public int screenWidthPixels = 640;
public int screenHeightPixels = 480;
private int counter;
private int x = 1;
private float alpha = 1;
private final int DELAY = 15;
private final int INITIAL_DELAY = 200;
public GamePanel() {
this.setPreferredSize(new Dimension(screenWidthPixels, screenHeightPixels));
this.setBackground(Color.black);
this.setDoubleBuffered(true);
this.setFocusable(true);
this.requestFocus();
counter = 0;
JButton testButton = new JButton("Button Test");
this.add(testButton);
JLabel label = new JLabel(new String("Label test"));
label.setVisible(true); // Doesn't seem to be needed.
this.add(label);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.WHITE);
g2.drawString("Game Panel Testing: " + counter,128,129);
g2.dispose();
}
#Override
public void actionPerformed(ActionEvent e) {
repaint();
update();
}
void startGameThread() {
gameLoopTimer = new Timer(DELAY,this);
gameLoopTimer.setInitialDelay(INITIAL_DELAY);
gameLoopTimer.start();
}
}
That code draws "Game Panel Testing: " and the incrementing counter, but no button and no label.
If I comment out the entire paintComponent I'm overriding, the button and label appear as expected.
What I can't wrap my head around is how to get the label and button to appear again once paintComponent is overridden. I thought the super.paintComponent(g) would take care of that automatically, but clearly I'm missing something here. How on earth can I add a bunch of JLabels to this game loop instead of having to manually handle moving of g2 drawn BufferedImages on mouse drag?

The jlabels are not drawn since you have overridden the paintComponent method.
The call to super is on the super class, so you have misunderstood how that call works.
If you put your in a class that inherits from your class with jlabels it will work.

JFrame does not add component when JButton is pressed

My code is basically about having a frame and it has a button. You press the button you can draw rectangles, getting coordinates from the mouse press and the mouse release.
Now, if you remove the button the code works perfectly, here is the code.
//testing file
package ActionTest;
import java.awt.*;
import javax.swing.*;
public class MouseTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new MouseFrame();
frame.setTitle("MouseTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setSize(500,500);
}
});
}
}
My frame, calls on the mouse component
package ActionTest;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class MouseFrame extends JFrame
{
public MouseFrame()
{
add(new MouseComponent());
}
}
The component class: handles mouse clicks and drawing the rectangle
package ActionTest;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import javax.swing.*;
public class MouseComponent extends JComponent
{
Point first;
Point second;
private ArrayList<Rectangle2D> rectangles;
public MouseComponent()
{
rectangles = new ArrayList<>();//contains rectangles
addMouseListener(new MouseHandler());
}
//paint method of the component, simply re-paint the array
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
for (Rectangle2D r : rectangles)
g2.draw(r);
}
/**
* creates a rectangle and adds it to the rectangles ArrayList
* then repaint the component
* inside some operations to deal with rectangle drawing nothing to do with the issue
* #param p1: first coordinates
* #param p2: second coordinates
*/
public void addRec(Point2D p1, Point2D p2)
{
double w, h, x, y;
double x1 = p1.getX();
double y1 = p1.getY();
double x2 = p2.getX();
double y2 = p2.getY();
if(x1 <= x2){
x = x1;
w = x2-x1;
}
else{
x = x2;
w = x1-x2;
}
if (y1 <= y2){
y = y1;
h = y2-y1;
}
else{
y = y2;
h = y1-y2;
}
rectangles.add(new Rectangle2D.Double(x, y, w, h));
repaint();
}
//records mouse click and mose release
//you press the mouse that is the 1st coordinates
//you release it that is the 2nd coordinates
//pass both to the addRec method
private class MouseHandler extends MouseAdapter
{
#Override
public void mousePressed(MouseEvent event)
{
first = event.getPoint();
}
#Override
public void mouseReleased(MouseEvent event)
{
second = event.getPoint();
addRec(first, second);
}
}
}
It works perfectly. However, going back to the original problem, if I add a button, and then when the button pressed go ahead and begin drawing rectangles it doesn't work.
Here is the modified frame class
package ActionTest;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class MouseFrame extends JFrame
{
private JPanel buttonPanel;
public MouseFrame()
{
JFrame frame = this;
buttonPanel = new JPanel();
JButton rec = new JButton("Rectangle");
rec.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent event)
{
System.out.println("pressed");
frame.add(new MouseComponent());
}});
buttonPanel.add(rec);
add(buttonPanel);
}
}
Thanks in advance.

frame.add(new MouseComponent());
The size of a newly created component is (0, 0) so there is nothing to paint. So you need to invoke the layout manager when you add a component to a visible GUI.
frame.add(new MouseComponent());
frame.revalidate();
frame.repaint();
Note this will only work if the layout manager allows you to add multiple components to the frame. The default layout manager for a frame is the BorderLayout and only a single components can be added to the CENTER of the BorderLayout.
So maybe you need to add the button using:
frame.add(button, BorderLayout.PAGE_START);
Read the section from the Swing tutorial on How to Use Layout Managers for more information and working examples.
Also, any time you do custom painting you need to override the getPreferredSize() method of the custom component so the layout managers can do their job.

How to prevent the JPanel from being updated?

I'm creating a sort of paint application. The user can move a circle in a JPanel by pressing/dragging the mouse.
I have a JCheckBoxMenuItem in one of my JMenus:
JCheckBoxMenuItem checkitem = new JCheckBoxMenuItem("Draw mode",false);
When it is not activated, the circle can only be moved (by dragging/pressing) and the previous circle will be erased.
When it is activated, the circle can only be moved, but the previous circle will not be erased when dragging/pressing the mouse ( This works the same way as a paint program )
Shortened version of my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class GUI extends JFrame implements MouseListener, MouseMotionListener, ActionListener, ItemListener
{
JPanel mainPan, colorPan;
Color color = Color.BLACK;
JCheckBoxMenuItem checkitem;
boolean clear = true;
public GUI(String header)
{
maker();
mainPan.addMouseListener(this);
mainPan.addMouseMotionListener(this);
add(mainPan , BorderLayout.CENTER);
add(colorPan, BorderLayout.PAGE_END);
}
public void maker()
{
colorPan = new JPanel();
colorPan.setLayout(new GridLayout(1, 0));
mainPan = new JPanel(){
#Override
public void paintComponent(Graphics g)
{
//g.setColor(Color.WHITE);
//g.fillRect(0,0,getWidth(),getHeight());
if(clear)
super.paintComponent(g); //Do the same thing as above(Clear JPanel)
g.setColor(color);
g.fillOval(x,y,50,50); //x and y are integer variables that I use in my full program
}
};
checkitem = new JCheckBoxMenuItem("Draw mode",false);
//After adding this to a JMenu,
checkitem.addItemListener(this);
}
public void itemStateChanged(ItemEvent e)
{
if(e.getStateChange() == ItemEvent.SELECTED)
{
clear = false;
}
else
{
clear = true;
}
}
}
The below screenshot shows the output of my full program:
colorPan is the JPanel full of JButtons of different colors. The top of it is mainPan.
Right now, the "Draw mode" doesn't work as expected. I had always thought that super.paintComponent(g); was the one that clears/resets the screen when repaint() is called. But I removed that and was quite surprised to see the program behave the same way.
Basically, my problem is here:
if(clear)
super.paintComponent(g);
I need to prevent everything from being cleared when repaint() is called. How do I achieve what I want?

It is not in this code where changes should be made. And it is not paint method which should be changed. Paint paints whenever is required either by your or by system. When window is resized or moved or partially covered - it uses paint to paint picture again.
What you should really do is to stop updating coordinates for your painted oval. It could be done in mouse listener or in coordinates setter or, better, in control part which manages these coordinates. Your checkbox should control ability to change your model. It should not control painting.
There is commonly used pattern Model-View-Controller - look at it. Maybe it could look like overkill for such small application but even Swing itself is built on this pattern so you already follow it. Issues rise when you try to break it. So - don't.

You can't "prevent the JPanel from being updated;" paintComponent() will be called asynchronously, as required by the system. Instead, condition attributes of your view class in a way that allows your implementation of paintComponent() to render everything whenever it is called.
In the example below, the foreground color is changed with each mouse click and paintComponent() uses the revised setting. In the more elaborate example cited here, ClearAction clears the List<Node> and List<Edge> that define the graph's model. Absent a call to super.paintComponent(g), otherwise required for an opaque component, a call to fillRect() in paintComponent() cleans up any leftover selection artifacts.
public void actionPerformed(ActionEvent e) {
nodes.clear();
edges.clear();
repaint();
}
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
/** #see https://stackoverflow.com/a/5312702/230513 */
public class MouseDragTest extends JPanel {
private static final String TITLE = "Drag me!";
private static final Random r = new Random();
private static final int W = 640;
private static final int H = 480;
private Point textPt = new Point(W / 2, H / 2);
private Point mousePt;
private Color color = Color.black;
public MouseDragTest() {
this.setFont(new Font("Serif", Font.ITALIC + Font.BOLD, 32));
this.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
mousePt = e.getPoint();
setColor(Color.getHSBColor(r.nextFloat(), 1, 1));
repaint();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
#Override
public void mouseDragged(MouseEvent e) {
int dx = e.getX() - mousePt.x;
int dy = e.getY() - mousePt.y;
textPt.setLocation(textPt.x + dx, textPt.y + dy);
mousePt = e.getPoint();
repaint();
}
});
}
public void setColor(Color color) {
this.color = color;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(W, H);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(color);
int w2 = g.getFontMetrics().stringWidth(TITLE) / 2;
g.drawString(TITLE, textPt.x - w2, textPt.y);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame f = new JFrame(TITLE);
f.add(new MouseDragTest());
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
});
}
}

Java: Using graphics component within an ActionListener

I have two separate class and driver files, and in the class file I create the paint method:
public void paint(Graphics g){
g.drawLine(......
....
//along with all of my other draw commands
}
Further down in the code, I create a JButton and within this button's action listener I don't know how to use a Graphics object to create more graphics in the JFrame. Should I be adding something to my driver to make this happen, or is there a way to use these graphics within my action listener? Thank you, and any help is appreciated.

You need to draw everything within the paint method. The actionPerformed should only change the state of something already in the paint method, and then call repaint. For example
boolean drawHello = true;
boolean drawWorld = false;
protected void paintComponent(Graphics g) {
super.paintCompoent(g);
if (drawHello)
g.drawString("Hello", 50, 50);
if (drawWorld)
g.drawString("World", 10, 10);
}
Then in your actionPerformed, you can change the state of drawWorld to true and call repaint().
public void actionPerformed(ActionEvent e) {
drawWorld = true;
repaint();
}
So as you can see, everything should be drawn in the paintComponent method. You can just hide and paint renderings, and make them "visible" from a action command. You should already have predefined what could posibly be drawn. Then just change the state of it rendering
And as #MadPrgrammer pointed out, you should not be painting on top-level containers like JFrame. Instead paint on a custom JPanel or JComponent and override the paintComponent method, instead of JFrame and paint
Here's an example where I draw a new square every time the button is pressed. If look at the code, you will see that in the paintComponent method, I loop through a list of Squares and draw them, and in the actionPerformed all I do is add a new Square to the List and call repaint()
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
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 AddSquares {
private int R = 0;
private int G = 0;
private int B = 0;
private int xLoc = 0;
private int yLoc = 0;
List<Square> squares = new ArrayList<>();
private JButton addSquare = new JButton("Add Square");
private RectsPanel panel = new RectsPanel();
public AddSquares() {
addSquare.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
Color color = new Color(R, G, B);
squares.add(new Square(xLoc, yLoc, color));
panel.repaint();
R += 10;
G += 20;
B += 30;
xLoc += 20;
yLoc += 20;
}
});
JFrame frame = new JFrame("Draw Squares");
frame.add(panel, BorderLayout.CENTER);
frame.add(addSquare, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
private class RectsPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
for (Square square : squares) {
square.drawSquare(g);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(250, 250);
}
}
private class Square {
int x = 0;
int y = 0;
Color color;
public Square(int x, int y, Color color) {
this.x = x;
this.y = y;
this.color = color;
}
public void drawSquare(Graphics g) {
g.setColor(color);
g.fillRect(x, y, 75 ,75);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
AddSquares addSquares = new AddSquares();
}
});
}
}

It's difficult to be 100%, but it would seem as you don't understand how custom painting is performed in Swing.
Start by taking a look at Performing Custom Painting and Painting in AWT and Swing.
Essentially, painting is arranged by the Repaint Manager, which decides what and when something should be painted. It then calls (through a chain of methods) the paint method of the components it thinks need to be updated, passing it a reference to a Graphics context that should be used to actually paint on.
Basically, when ever your paint method is called, you should create paint the current state of your painting.
You should avoid overriding paint and instead use paintComponent from classes the extend JComponent

Your question is a little on the vague side as to what you are actually wondering about but generally speaking:
We don't override paint in Swing, we override paintComponent.
If you are already aware of this, you may be overriding paint because you are doing it on a JFrame and you found that JFrame does not have a paintComponent method. You shouldn't override paint on a JFrame. Instead, create a JPanel or something to put inside the frame and override paintComponent on the panel.
Question about the ActionListener.
It sounds like you are wanting to do painting outside of paintComponent in which case probably the best way is to do painting to a separate Image. Then you paint the Image on to the panel in paintComponent. You can also put an Image in a JLabel as an ImageIcon. Here is a very simple drawing program using MouseListener that demonstrates this (taken from here):
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
class PaintAnyTime {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new PaintAnyTime();
}
});
}
final BufferedImage image = (
new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB)
);
final JFrame frame = new JFrame();
final JLabel label = new JLabel(new ImageIcon(image));
final MouseAdapter drawer = new MouseAdapter() {
Graphics2D g2D;
#Override
public void mousePressed(MouseEvent me) {
g2D = image.createGraphics();
g2D.setColor(Color.BLACK);
}
#Override
public void mouseDragged(MouseEvent me) {
g2D.fillRect(me.getX(), me.getY(), 3, 3);
label.repaint();
}
#Override
public void mouseReleased(MouseEvent me) {
g2D.dispose();
g2D = null;
}
};
PaintAnyTime() {
label.setPreferredSize(
new Dimension(image.getWidth(), image.getHeight())
);
label.addMouseListener(drawer);
label.addMouseMotionListener(drawer);
frame.add(label);
frame.pack();
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
#MadProgrammer has already linked to the articles that I was going to link to.

How do I create a rectangle that is a JPanel?

I have picture as a JLabel and what I want to do is when I click the JLabel, there would be another Jlabel in a form of rectangle would appear.
I tried using paintComponent or paint and unfortunately, it doesn't work for my program. So I have to think that there are other ways, other than paintComponent and/or paint.
The aim is tag to a certain part of an image with a name, like in Facebook.

Wow.
Based on Pace's description of the problem, you're going to have to do the following (I think):
The picture will have to be painted directly on a JPanel. This is so when someone clicks on the picture, you can get the mouse x and y coordinates through the JPanel action listener.
You will then create a JDialog with a transparent JPanel that has a border, a text box for the name, and an OK button together. (Might as well put everything together in one dialog window.) The JDialog will be movable, but you're going to have to create a JDialog listener that keeps track of the x and y coordinates of the top left edge or the center of the transparent JPanel in the JDialog.
The JDialog JPanel won't really be transparent. You'll have to create the illusion of transparency by noting the position of the JDialog JPanel on the picture JPanel, and copying the part of the image from the picture JPanel to the JDialog JPanel.
The rest should be rather straightforward, compared to getting the JDialog to work properly.
Edited to add: Here's an extension of JPanel that will draw a picture directly on the JPanel and process mouse pressed events.
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseEvent;
import javax.swing.JPanel;
import javax.swing.event.MouseInputAdapter;
public class PicturePanel extends JPanel {
private static final long serialVersionUID = 1L;
protected Image picture;
public PicturePanel(Image picture) {
this.picture = picture;
createPartControl();
}
protected void createPartControl() {
new JPanel();
int width = picture.getWidth(getParent());
int height = picture.getHeight(getParent());
addMouseListener(new CoordinateListener());
setPreferredSize(new Dimension(width, height));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
int width = picture.getWidth(getParent());
int height = picture.getHeight(getParent());
g.drawImage(picture, 0, 0, width, height, null);
}
public class CoordinateListener extends MouseInputAdapter {
#Override
public void mousePressed(MouseEvent event) {
int x = event.getX();
int y = event.getY();
System.out.println("(" + x + ", " + y + ")");
}
}
}