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Repaint() does not work after adding more components to JPanel in Swing, Java

I am starting with Java and want to make a simple pong game to get into the ways of displaying stuff in java. I have created 2 classes that both extend JPanel and call the repaint() function every 16.6 milliseconds. I added both to a JPanel which I added to the frame, but only the component I added first displays.
I've tried to revalidate() after repaint() in both classes and made sure that the Timer actually works and that it's actionPerformed() method is actually called.
This is the main method:
public class Main {
public static void main(String[] args){
JFrame frame = new JFrame("Pong");
//...
JPanel mainPanel = new JPanel();
mainPanel.add(new Player());
mainPanel.add(new Ball(frameWidth/2, frameHeight/2 -40));
frame.add(mainPanel);
}
}
This is the important code for the classes (It's basically the same for both of them):
public class Player extends JPanel {
public Player(){
setPreferredSize(new Dimension(Main.frameWidth, Main.frameHeight));
setBackground(Color.BLACK);
new Timer(1000/60, new ActionListener(){
public void actionPerformed(ActionEvent e){
update();
repaint();
}
}).start();
}
//...
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(x, y, width, height);
}
}
(Of coure I left things like #Override or unneseccary functions out to shorten the code)
This code only paints the Player, altough I want it to display all the components of mainPanel.
This is an example that you can (hopefully) run. I had to split it up into 3 files, since I suck at anonymus classes:
Main.java
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args){
JFrame frame = new JFrame("Pong");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 800);
JPanel mainPanel = new JPanel();
mainPanel.add(new Player());
mainPanel.add(new Ball());
frame.add(mainPanel);
frame.setVisible(true);
}
}
///////
Player.java
//////
import javax.swing.JPanel;
import javax.swing.Timer;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Player extends JPanel{
private int x = 20, y = 300, width = 20, height = 100;
public Player(){
setPreferredSize(new Dimension(800, 800));
setBackground(Color.BLACK);
new Timer(1000/60, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
repaint();
}
}).start();
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(x, y, width, height);
}
}
//////
Ball.java
//////
import javax.swing.JPanel;
import javax.swing.Timer;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ball extends JPanel{
private int x = 20, y = 300, width = 20, height = 100;
public Ball(){
setPreferredSize(new Dimension(800, 800));
setBackground(Color.BLACK);
new Timer(1000/60, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
repaint();
}
}).start();
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(x, y, width, height);
}
}

In method paintComponent() of class Player, you paint the exact same Rectangle each time. In order to achieve animation, each time you paint the rectangle you need to change either its size or location or both. What do you expect the Player to do? Should it move up and down along the left edge of the window? Have you seen the lesson entitled How to Use Swing Timers which is part of Oracle's Java Tutorial?
EDIT
I see now that Player hides Ball, because of the default layout manager of JPanel. The below code is essentially the code you posted but I set GridLayout as the layout manager for mainPanel. Also, a java source code file may contain more than one class but exactly one class must be public. Hence in the below code only class Main is public.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame("Pong");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel mainPanel = new JPanel(new GridLayout(0, 2));
mainPanel.add(new Player());
mainPanel.add(new Ball());
frame.add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
class Player extends JPanel {
public Player() {
setBorder(BorderFactory.createLineBorder(Color.RED, 2, false));
setPreferredSize(new Dimension(800, 800));
setBackground(Color.BLACK);
new Timer(1000 / 60, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
repaint();
}
}).start();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(20, 100, 20, 100);
}
}
class Ball extends JPanel {
public Ball() {
setBorder(BorderFactory.createLineBorder(Color.CYAN, 2, false));
setPreferredSize(new Dimension(800, 800));
setBackground(Color.BLACK);
new Timer(1000 / 60, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
repaint();
}
}).start();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(300, 300, 10, 10);
}
}
And here is a screen capture of the GUI...

I just realized that if I extend my window manually, the second JPanel shows up under the one responsible for the Player! This means that I'll need to set the Panels position somehow, right?
#Abra

Animation Constructor not working in Java GUI

Hello I am new to Java GUI I made a second.java which is as below:
package theproject;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class second extends JPanel implements ActionListener {
private Timer animator;
private ImageIcon imageArray[];
private int delay=50, totalFrames=8, currentFreames=1;
public second()
{
imageArray= new ImageIcon[totalFrames];
System.out.println(imageArray.length);
for(int i=0; i<imageArray.length;i++)
{
imageArray[i]=new ImageIcon(i+1+".png");
System.out.println(i+1);
}
animator= new Timer(delay, this);
animator.start();
}
public void paintComponent(Graphics g )
{
super.paintComponent(g);
if(currentFreames<8)
{
imageArray[currentFreames].paintIcon(this, g, 0, 0);
currentFreames++;
System.out.println(currentFreames);
}
else{
currentFreames=0;
}
}
#Override
public void actionPerformed(ActionEvent arg0) {
repaint();
}
}
And a Gui calling the constructor second and output is not showing . Can you please guide me what should I do and the gui is given below:
package theproject;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import javax.swing.JTextField;
public class Sav {
private JFrame frame;
private JTextField textField;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Sav window = new Sav();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Sav() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
textField = new JTextField();
textField.setBounds(10, 0, 261, 20);
frame.getContentPane().add(textField);
textField.setColumns(10);
JButton btnNewButton = new JButton("Submit");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
second s= new second();
frame.add(s);
}
});
btnNewButton.setBounds(273, -1, 89, 23);
frame.getContentPane().add(btnNewButton);
}
}
The gui has to basically call the constructor and which will showcase the animation on the screen If someone what i am doing wrong or if something that has to be done please let me know .

First, don't update the state within the paintComponent method, paint can occur for a number of reasons at any time, mostly without your interaction. Painting should simple paint the current state. In your ActionListener, you should advance the frame and make decisions about what should occur (like resetting the frame value)
Second, you never actually add second to anything, so it will never be displayed.
Third, you don't override getPreferredSize in second, so the layout managers will have no idea what size the component should be and will simply be assigned 0x0, making it as good as invisible as makes no difference
Fourth, you're using null layouts. This is going to make you life impossibly hard. Swing has been designed and optimised around the use of layout managers, they do important work in deciding how best to deal with differences in font metrics across different rendering systems/pipelines, I highly recommend that you take the time to learn how to use them
Fifthly, paintComponent has no business been public, no one should ever call it directly
Example
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;
public class Sav {
private JFrame frame;
private JTextField textField;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Sav window = new Sav();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Sav() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
textField = new JTextField(20);
frame.getContentPane().add(textField, gbc);
JButton btnNewButton = new JButton("Submit");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
second s = new second();
frame.add(s, gbc);
frame.getContentPane().revalidate();
frame.pack();
frame.setLocationRelativeTo(null);
}
});
frame.getContentPane().add(btnNewButton, gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public class second extends JPanel implements ActionListener {
private Timer animator;
private ImageIcon imageArray[];
private int delay = 50, totalFrames = 8, currentFreames = 1;
public second() {
imageArray = new ImageIcon[totalFrames];
for (int i = 0; i < imageArray.length; i++) {
imageArray[i] = new ImageIcon(getImage(i));
}
animator = new Timer(delay, this);
animator.start();
}
protected Image getImage(int index) {
BufferedImage img = new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
FontMetrics fm = g2d.getFontMetrics();
g2d.dispose();
String text = Integer.toString(index);
int height = fm.getHeight();
int width = fm.stringWidth(text);
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
g2d = img.createGraphics();
g2d.setColor(getForeground());
g2d.drawString(text, 0, fm.getAscent());
g2d.dispose();
return img;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(imageArray[0].getIconWidth(), imageArray[1].getIconHeight());
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
imageArray[currentFreames].paintIcon(this, g, 0, 0);
}
#Override
public void actionPerformed(ActionEvent arg0) {
currentFreames++;
if (currentFreames >= imageArray.length) {
currentFreames = 0;
}
repaint();
}
}
}
Your code is also not working. It increment the values of image set but do not displays the images
Works just fine for me...
imageArray[i]=new ImageIcon(i+1+".png"); will not generate any errors if the image can't be loaded for some reason (and it will load the images in the background thread, which is just another issue).
Instead, I would recommend using ImageIO.read instead, which will throw a IOException if the image can't be read for some reason, which is infinitely more useful. See Reading/Loading an Image for more details

Missing JPanel in JLayeredPane

I was working on an overlay for a JPanel but I have a slight problem, the transparency of the overlay sees straight through to the JFrame.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class GUI extends JFrame {
private GUI() {
super("Recorder Part");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
JLayeredPane layers = new Overlay();
add(layers);
pack();
getContentPane().setBackground(Color.GREEN);
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> new GUI());
}
private class Overlay extends JLayeredPane {
JPanel base;
JPanel overlay;
private Overlay() {
setPreferredSize(new Dimension(800, 100));
createBase();
createOverlay();
add(base, new Integer(0));
add(overlay, new Integer(1));
}
private void createBase() {
base = new JPanel();
base.setPreferredSize(new Dimension(800, 100));
base.setBounds(0, 0, 800, 100);
base.setBackground(Color.BLUE);
base.setOpaque(true);
base.add(new JLabel("Hello"));
}
private void createOverlay() {
overlay = new JPanel();
overlay.setPreferredSize(new Dimension(800, 100));
overlay.setBounds(0, 0, 800, 100);
overlay.setBackground(new Color(255, 0, 0, 0));
}
}
}
How can I fix this so that when the JPanel called overlay is transparent, the Jpanel called base can be seen and not the JFrame?
Edit
I found that this problem only occurs when the overlay panel has one dimension that is greater than or equal to the dimensions of the base panel. This can be seen by adjusting the size of the frame in this example.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class GUI extends JFrame {
private GUI() {
super("Recorder Part");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
JLayeredPane layers = new Overlay();
add(layers);
pack();
getContentPane().setBackground(Color.GREEN);
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> new GUI());
}
private class Overlay extends JLayeredPane {
JPanel base;
JPanel overlay;
private Overlay() {
addComponentListener(new Resize());
setPreferredSize(new Dimension(800, 100));
createBase();
createOverlay();
add(base, new Integer(0));
add(overlay, new Integer(1));
}
private void createBase() {
base = new JPanel();
base.setLocation(0, 0);
base.setBackground(Color.BLUE);
base.setOpaque(true);
base.add(new JLabel("Hello"));
}
private void createOverlay() {
overlay = new JPanel();
overlay.setLocation(0, 0);
overlay.setSize(new Dimension(800, 100));
overlay.setBackground(new Color(255, 0, 0, 128));
}
private class Resize extends ComponentAdapter {
#Override
public void componentResized(ComponentEvent e) {
System.out.println("Resized");
base.setSize(new Dimension(getParent().getWidth(), getParent().getHeight()));
}
}
}
}
This is undesirable as the overlay panel needs to be the exact same size of the base panel. I would appreciate any help.

I have the felling that this is a bug. Change the bounds so it doesn't fully overlap the base to o see what happens:
overlay.setBounds(0, 0, 799, 100); // or (1, 0, 800, 100)
probably some kind of optimization, like ignoring a component if it is being completely obscured by another component, but without considering transparency in that optimization [:-|
EDIT:
that is definitively the problem - paintChildren of JComponent does some kind of optimization based on children being totally obscured by other children.
I found two solutions, the first one is probably the correct one- set the overlay to non-opaque:
overlay.setOpaque(false);
this has the drawback that the background color is not being used at all.
Second is more a workarround - make the JLayeredPane return true for optimizedDrawingEnabled, this will stop the JComponent from doing it:
private class Overlay extends JLayeredPane {
/// ...
#Override
public boolean isOptimizedDrawingEnabled() {
return true;
}
}
but not sure what may stop working by doing that, so I would prefer the first solution!

3 buttons to draw 3 different objects in a jPanel

i have a simple question but for some reason I'm stuck and cant figure it out.
I have a simple code with 3 buttons in a JPanel each one of the buttons should draw at the JPanel with the overriden PaintComponent and it does but What i want to do is make the shapes stay.
(after i will change it to random positions )
any help would be apreciated thank you!
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Ex3 extends JFrame implements ActionListener
{
JButton circle, triang, square;
JPanel jp, jButton;
boolean drawSq, drawCir, drawTr;
public static void main(String[] args)
{
JFrame frame = new Ex3();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public Ex3()
{
super("Ex3");
setSize(400, 500);
circle = new JButton("Circle");
triang = new JButton("Triangle");
square = new JButton("Square");
drawCir = false;
drawSq = false;
drawTr = false;
//setLayout(new FlowLayout(FlowLayout.CENTER, 20, 30));
jButton = new JPanel();
jp = new CustomPanel();
circle.addActionListener(this);
triang.addActionListener(this);
square.addActionListener(this);
jButton.add(circle);
jButton.add(triang);
jButton.add(square);
jButton.add(new JLabel("Kayy"));
jp.setBackground(Color.gray);
add(jp, BorderLayout.CENTER);
add(jButton, BorderLayout.NORTH);
}
#Override
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == circle)
{
drawCir = true;
System.out.println("created cricle");
}
if(e.getSource() == triang)
{
drawTr = true;
System.out.println("created triangle");
}
if(e.getSource() == square)
{
drawSq = true;
System.out.println("created square");
}
repaint();
}
class CustomPanel extends JPanel
{
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if(drawSq)
{
g.setColor(Color.blue);
g.drawRect(((int)Math.random()* 20), 50, 200, 150);
drawSq = false;
}
else if(drawTr)
{
g.setColor(Color.green);
}
else if(drawCir)
{
g.setColor(Color.red);
g.drawOval(182, 124, 200, 200);
}
else
{
}
//drawSq = false;
drawTr = false;
drawCir = false;
}
}
}

What i want to do is make the shapes stay
Then you need to repaint the shapes every time the component is repainted.
There are two common approaches to do this:
paint to a BufferedImage
keep a list of Object to paint and iterate through the list to paint each object
Check out Custom Painting Approaches for working examples of each approach. Which approach you use will depend on your exact requirements.
Also, you should never change the state of your component in the painting method. You can't control when the paintComponent() method is invoked. Sometimes the system will repaint a component. So the presence of your Boolean variables indicates a design problem.

java Swing button action

I am new in java and i wanted to work on a simple paint program using java swing.
my simple paint program should draw a shape like triangle, circle and square whenever i clicked on buttons.
i managed to draw these shapes and print it without buttons but i can not do it using ActionListener?
As you see i have a single button at the moment, i want to draw the oval whenever this button is clicked.
This is the code that i am working on it so far:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class PaintProject extends JComponent implements ActionListener{
public static void main(String[] args) {
JFrame frame=new JFrame("NEW PAINT PROGRAME!");
JButton button1=new JButton("ADD");
PaintProject paint=new PaintProject();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLayout(new FlowLayout());
frame.add(paint);
frame.add(button1);
frame.pack();
frame.setVisible(true);
}
#Override
public Dimension getPreferredSize(){
return new Dimension(500,500);
}
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.red);
g.fillOval(0,0, 100, 100);
}
#Override
public void actionPerformed(ActionEvent e) {
}
}

Could you please take following steps:
Step 1:
Insert button1.addActionListener(paint); just after PaintProject paint=new PaintProject(); in the main method of PaintProject.java
Step 2:
Remove the method named protected void paintComponent(Graphics g). Instead create following method:
private void drawOval(){
Graphics g = this.getGraphics();
g.setColor(Color.red);
g.fillOval(0,0, 100, 100);
}
Step 3:
Call the above method as follows:
#Override
public void actionPerformed(ActionEvent e) {
drawOval();
}
EDIT:
Following example demonstrates how to draw two shapes when respective buttons are clicked:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.WindowConstants;
public class PaintProject extends JComponent implements ActionListener {
public static void main(String[] args) {
JFrame frame = new JFrame("NEW PAINT PROGRAME!");
JButton ovalButton = new JButton("Oval");
ovalButton.setActionCommand("Oval");
JButton rectangleButton = new JButton("Rectangle");
rectangleButton.setActionCommand("Rectangle");
PaintProject paint = new PaintProject();
ovalButton.addActionListener(paint);
rectangleButton.addActionListener(paint);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLayout(new FlowLayout());
frame.add(paint);
frame.add(ovalButton);
frame.add(rectangleButton);
frame.pack();
frame.setVisible(true);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
private void drawOval() {
Graphics g = this.getGraphics();
g.setColor(Color.red);
g.fillOval(0, 0, 100, 100);
}
private void drawRectangle() {
Graphics g = this.getGraphics();
g.setColor(Color.green);
g.fillRect(150, 150, 100, 100);
}
#Override
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if (command.equals("Oval")) {
drawOval();
} else if (command.equals("Rectangle")) {
drawRectangle();
}
}
}