We Keep Coding

Eclipse is not running Java method: public void paint (Graphics g)

I'm new to Eclipse, recently swapped from Bluej which ran my codes reliably. In Eclipse, it sometimes runs and sometimes just doesn't run the paint method and I'm not sure why. The same code was running this morning and now it decides to not run and I'm not sure what to do.
Main method:
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import Asset.Paddle;
import Asset.Puck;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;
import java.awt.BorderLayout;
public class setup implements KeyListener, MouseListener, MouseMotionListener, Runnable {
int width = 100;
int height = 100;
int scale = 8;
public static setup setup;
JFrame frame;
JPanel main;
Graphic graphic;
Puck puck;
Paddle paddle1,paddle2;
boolean running, up = true, up2 = true;
boolean menu = false, b1, b2, b3;
int winSize;
public setup() {
puck = new Puck((width*scale)/2,(width*scale)/2,20,20);
paddle1 = new Paddle(width*scale/8-20,height*scale/2,20,100);
paddle2 = new Paddle(width*scale/8*7,height*scale/2,20,100);
frame();
}
public void frame() { //Frame setup
frame = new JFrame("Pong");
frame.setSize(width * scale,height * scale);
frame.setLayout(new BorderLayout());
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container c1 = frame.getContentPane();
Dimension winSize = frame.getSize();
System.out.println(winSize);
graphic = new Graphic(puck,paddle1,paddle2);
graphic.addKeyListener(this);
graphic.addMouseListener(this);
graphic.addMouseMotionListener(this);
main = new JPanel();
main.setLayout(new BorderLayout());
main.setSize(width * scale,height * scale);
main.add(graphic,BorderLayout.CENTER);
start();
c1.add(main);
graphic.requestFocus();
}
public void start() { //running = true
new Thread(this).start();
running = true;
menu = true;
RENDER();
}
public void stop() {
running = false;
}
public void run() { //Game
while(running == true) {
try {
Thread.sleep(10);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
if(puck.getY() < 0 || puck.getY() > height * scale) {
puck.reverseY();
}
paddle1.run();
paddle2.run();
puck.run();
RENDER();
}
}
public void RENDER() {
graphic.UPDATEPADDLE(paddle1,paddle2);
graphic.UPDATEPUCK(puck);
graphic.repaint();
}
public void keyPressed(KeyEvent evt) {
if(evt.getKeyCode() == 81) { // Q
paddle1.setYVel(-2);
up = true;
}
if(evt.getKeyCode() == 65) { // A
paddle1.setYVel(2);
up = false;
}
if(evt.getKeyCode() == 80) { // P
paddle2.setYVel(-2);
up2 = true;
}
if(evt.getKeyCode() == 76) {
paddle2.setYVel(2);
up2 = false;
}
}
public void keyReleased(KeyEvent evt) {
if(evt.getKeyCode() == 81 && up ) { // Q
paddle1.setYVel(0);
}
if(evt.getKeyCode() == 65 && !up) { // A
paddle1.setYVel(0);
}
if(evt.getKeyCode() == 80 && up2) { // P
paddle2.setYVel(0);
}
if(evt.getKeyCode() == 76 && !up2) { // L
paddle2.setYVel(0);
}
}
public void keyTyped(KeyEvent evt) {}
public void mouseClicked(MouseEvent e) {
// if(e.getX() > 375 && e.getX() < 375 + 200 && e.getY() > 400 && e.getY() < 400 + 50) {
// menu = false;
// System.out.println("clicked");
// graphic.UPDATEBUTTON(b1,b2,b3);
// graphic.UPDATEMENU(menu);
// start();
// graphic.repaint();
// }
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public static void main(String[] args) {
setup = new setup();
}
public void mouseDragged(MouseEvent e) {
}
public void mouseMoved(MouseEvent e) {
if(e.getX() > 375 && e.getX() < 375 + 200 && e.getY() > 400 && e.getY() < 400 + 50) {
b1 = true;
graphic.UPDATEBUTTON(b1,b2,b3);
graphic.repaint();
}
else {
b1 = false;
graphic.UPDATEBUTTON(b1,b2,b3);
graphic.repaint();
}
}
}
Paddle:
package Asset;
public class Paddle {
double x, y, yVel, h, w;
public Paddle(double xx, double yy, int width, int height) {
x = xx;
y = yy;
h = height;
w = width;
}
public int getX() {
return (int)x;
}
public int getY() {
return (int)y;
}
public int getH() {
return (int)h;
}
public int getW() {
return (int)w;
}
public void setYVel(int yVelocity) {
yVel = yVelocity;
}
public void run() {
y += yVel;
if(y < 0) {
yVel = 0;
y = 0;
}
}
}
Puck:
package Asset;
public class Puck {
double x,y,w,h;
double xVel = 0;
double yVel = 3;
public Puck(double xx, double yy,int width,int height) {
x = xx;
y = yy;
w = width;
h = height;
x++;
}
public void reverseY() {
yVel *= -1;
}
public void reverseX() {
xVel *= -1;
}
public int getX() {
return (int)x;
}
public int getY() {
return (int)y;
}
public int getW() {
return (int)w;
}
public int getH() {
return (int)h;
}
public void run() {
x += xVel;
y += yVel;
}
}
Setup:
import java.awt.*;
import javax.swing.*;
import Asset.Paddle;
import Asset.Puck;
public class Graphic extends JPanel {
private static final long serialVersionUID = 2273791975624707192L;
Puck ppuck;
Paddle ppaddle1,ppaddle2;
boolean mmenu = true;
boolean bb1,bb2,bb3;
public Graphic(Puck puck,Paddle paddle1,Paddle paddle2) {
ppuck = puck;
ppaddle1 = paddle1;
ppaddle2 = paddle2;
}
public void UPDATEMENU(boolean menu) {
mmenu = menu;
}
public void UPDATEPADDLE(Paddle paddle1, Paddle paddle2) {
ppaddle1 = paddle1;
ppaddle2 = paddle2;
}
public void UPDATEPUCK(Puck puck) {
ppuck = puck;
}
public void UPDATEBUTTON(boolean b1,boolean b2, boolean b3) {
bb1 = b1;
bb2 = b2;
bb3 = b3;
}
public void paint (Graphics g) {
super.paint(g);
g.setColor(Color.black);
g.fillRect(0, 0, 1000, 1000);
if (mmenu) { //menu
if(bb1) {
g.setColor(Color.blue);
g.setFont(new Font("TimesRoman", Font.PLAIN, 50));
g.drawString("START", 390, 440);
}
else {
g.setColor(Color.white);
g.setFont(new Font("TimesRoman", Font.PLAIN, 50));
g.drawString("START", 390, 440);
}
}
else {
g.setColor(Color.white);
g.fillOval(ppuck.getX(), ppuck.getY(), ppuck.getW(), ppuck.getH());
g.fillRect(ppaddle1.getX(), ppaddle1.getY(), ppaddle1.getW(), ppaddle1.getH());
g.fillRect(ppaddle2.getX(), ppaddle2.getY(), ppaddle2.getW(), ppaddle2.getH());
}
}
}

So, two "basic" problems...
One, if you modify the UI after the frame is visible, you must call revalidate and repaint too trigger a layout and paint pass. A simpler solution, in your case, would be to call setVisible AFTER you've established the UI
public void frame() { //Frame setup
frame = new JFrame("Pong");
frame.setSize(width * scale, height * scale);
frame.setLayout(new BorderLayout());
frame.setLocationRelativeTo(null);
//frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container c1 = frame.getContentPane();
//...
start();
c1.add(main);
graphic.requestFocus();
frame.setVisible(true);
}
Second...
This one's a little more complicated, but, you start your Thread and then update the state which it relies on to keep running
public void start() { //running = true
new Thread(this).start();
running = true;
menu = true;
RENDER();
}
While very, very unlikely, it's possible that the thread will inspect the state before you change it ... or because of the way the memory model works, won't see the change.
Better to set it before hand...
public void start() { //running = true
running = true;
new Thread(this).start();
menu = true;
RENDER();
}
You should also consider making it volatile
Having said that...
You're going around it all the wrong way.
To start with, don't try and do all the rendering for all the states in the single view, instead, use seperate views to different states (such as the start screen and the game screen).
You could then make use of CardLayout or simply overlay the containers onto of each other when you want to switch between them.
Next, you should avoid using KeyListener, it's troublesome at the best of times. Instead, make us of the key bindings API, then you won't need to post another question about why KeyListener has stopped working.
Next, Swing is single threaded and not thread safe. This means you should not be performing blocking or long running operations within the context of the Event Dispatching Thread or updating the UI or a state the UI depends on from outside of it.
Take a look at Concurrency in Swing for more details.
The simple solution in this case is probably to use a Swing Timer, see How to use Swing Timers for more details.
I would, personally, make the "game" panel responsible for setting up the input and rendering management, but that's me.

Overrided paint method not being called after repaint is

My problem is essentially creating a physics engine with a few different scenarios. I would like to consolidate the different scenarios into one window by having buttons that run each individually. The frame works properly and the buttons show up and can be pressed; however, that print line in the pain method is never happening and from there I concluded that paint is not being called even after repaint is. I understand that they are not the same but I don't understand why paint isn't being accessed in this instance compared to others.
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Color;
import javax.swing.JButton;
public class PhysicsEngine extends JPanel{
double x ,y;
JFrame frame;
JPanel pan;
JButton b1;
JButton b2;
JButton b3;
JButton b4;
JButton b5;
public static void main(String[] args){
PhysicsEngine gui = new PhysicsEngine();
}
public PhysicsEngine(){
frame = new JFrame("Ball Engine");
pan = new JPanel();
frame.add(pan);
b1 = new JButton("1");
b1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event){
try{
startFirst();
}
catch(InterruptedException exception){}
}
});
pan.add(b1);
b2 = new JButton("2");
b2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
try{
startSecond();
}
catch(InterruptedException exception){}
}
});
pan.add(b2);
b3 = new JButton("3");
b3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
try{
startThird();
}
catch(InterruptedException exception){}
}
});
pan.add(b3);
b4 = new JButton("4");
b4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
try{
startFourth();
}
catch(InterruptedException exception){}
}
});
pan.add(b4);
b5 = new JButton("5");
b5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
try{
startFifth();
}
catch(InterruptedException exception){}
}
});
pan.add(b5);
frame.setSize(600, 600);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g) {
super.paint(g);
System.out.println(""+y);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.RED);
g2d.fillOval((int)x, (int)y, 30, 30);
}
public void startFirst() throws InterruptedException{
x = 300;
for(int t = 1;;t++){
//xPos= 0*t*t + 0*t + 300 this is constant at 300
if(y>=615) break; //stops the loop when the ball is off the screen
y = .1*t*t + 0*t + 80; //parametric equation for y
repaint();
Thread.sleep(10);
}
}
public void startSecond() throws InterruptedException{
x = 300;
for(int t = 1;;t++){
//xPos= 0*t*t + 0*t + 300 this is constant at 300
if(y>=615) break; //stops the loop when the ball is off the screen
y = .1*t*t - 10*t + 550; //parametric equation for y
repaint();
Thread.sleep(10);
}
}
public void startThird() throws InterruptedException{
for(int t = 1;;t++){
if(y>=615||x>=615) break; //stops the loop when the ball is off the screen
y = .1*t*t - 10*t + 550; //parametric equation for y
x = 0*t*t + 5*t + 50; //parametric equation for x
repaint();
Thread.sleep(10);
}
}
public void startFourth() throws InterruptedException{
for(int t = 1;;t++){
//xPos= 0*t*t + 0*t + 300 this is constant at 300
if(y>=615||x>=615) break; //stops the loop when the ball is off the screen
y = t*t*t + 50; //given parametric equation for y
x = t - 4; //given parametric equation for x
repaint();
Thread.sleep(10);
}
}
public void startFifth() throws InterruptedException{
for(int t = 1;t<500 /* goes for 5 seconds */;t++){
y = 200*Math.sin(t) + 300; //given parametric equation for y
x = 200*Math.cos(t) + 300; //given parametric equation for x
repaint();
Thread.sleep(10);
}
}
}

The basic problem is you are overriding the paint() method of the PhysicsEngine class. But you never add an instance of this class to the frame.
However, the bigger problem is the structure of your class. Your main class should not be extending a JPanel just so you can create a JFrame. The logic for creating the frame should be in the main() method and then your PysicsEngine panel should contain all the components you want to build for your frame. Also, custom painting should be done by overriding the paintComponent(...) method, not the paint() method.
Read the section from the Swing tutorial on Custom Painting for basic painting information and demos.
Then you can look at other sections in the tutorial for a better way to structure your code. For example the ButtonDemo code found in the How to Use Buttons tutorial will show you how to extend a JPanel and add buttons to it.

repaint() stores a request for refreshing a component, request that will be executed by the GUI thread later on. But a component will be refreshed only if it is visible on screen, alas your PhysicsEngine class doesn't seem to be used as a visible component in some visible GUI hierarchy.

Your paint method should be paintComponent and also should call the paintComponent method of super class.
And you don't add the PhysicsEngine JPanel into the JFrame, and it is very bad approach to create a JFrame in the constructor of JPanel subclass. I create a JFrame in the main method and create a object of PhysicsEngine (JPanel Subclass) and add it into the JFrame. I add the buttons by using this which reference to the PhysicsEngine (JPanel subclass) object.
Here is the working code:
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JButton;
public class PhysicsEngine extends JPanel {
double x, y;
JPanel pan;
JButton b1;
JButton b2;
JButton b3;
JButton b4;
JButton b5;
public static void main(String[] args) {
JFrame frame = new JFrame("Ball Engine");
PhysicsEngine gui = new PhysicsEngine();
frame.add(gui, BorderLayout.CENTER);
frame.setSize(600, 600);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public PhysicsEngine() {
b1 = new JButton("1");
b1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
try {
startFirst();
} catch (InterruptedException exception) {
}
}
});
this.add(b1);
b2 = new JButton("2");
b2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
startSecond();
} catch (InterruptedException exception) {
}
}
});
this.add(b2);
b3 = new JButton("3");
b3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
startThird();
} catch (InterruptedException exception) {
}
}
});
this.add(b3);
b4 = new JButton("4");
b4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
startFourth();
} catch (InterruptedException exception) {
}
}
});
this.add(b4);
b5 = new JButton("5");
b5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
startFifth();
} catch (InterruptedException exception) {
}
}
});
this.add(b5);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("" + y);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.RED);
g2d.fillOval((int) x, (int) y, 30, 30);
}
public void startFirst() throws InterruptedException {
x = 300;
for (int t = 1;; t++) {
// xPos= 0*t*t + 0*t + 300 this is constant at 300
if (y >= 615)
break; // stops the loop when the ball is off the screen
y = .1 * t * t + 0 * t + 80; // parametric equation for y
repaint();
Thread.sleep(10);
}
}
public void startSecond() throws InterruptedException {
x = 300;
for (int t = 1;; t++) {
// xPos= 0*t*t + 0*t + 300 this is constant at 300
if (y >= 615)
break; // stops the loop when the ball is off the screen
y = .1 * t * t - 10 * t + 550; // parametric equation for y
repaint();
Thread.sleep(10);
}
}
public void startThird() throws InterruptedException {
for (int t = 1;; t++) {
if (y >= 615 || x >= 615)
break; // stops the loop when the ball is off the screen
y = .1 * t * t - 10 * t + 550; // parametric equation for y
x = 0 * t * t + 5 * t + 50; // parametric equation for x
repaint();
Thread.sleep(10);
}
}
public void startFourth() throws InterruptedException {
for (int t = 1;; t++) {
// xPos= 0*t*t + 0*t + 300 this is constant at 300
if (y >= 615 || x >= 615)
break; // stops the loop when the ball is off the screen
y = t * t * t + 50; // given parametric equation for y
x = t - 4; // given parametric equation for x
repaint();
Thread.sleep(10);
}
}
public void startFifth() throws InterruptedException {
for (int t = 1; t < 500 /* goes for 5 seconds */; t++) {
y = 200 * Math.sin(t) + 300; // given parametric equation for y
x = 200 * Math.cos(t) + 300; // given parametric equation for x
repaint();
Thread.sleep(10);
}
}
}

KeyListener ignored

I am trying to make simple program, exercise actually - its description is included in attached code. My trouble is that keyPressed() method is completely ignored. Please take a look if possible and provide me with some hints on what I am doing wrong.
class exercise_chapter10_5
/*
White a program that creates a window with a menu bar. The menu bar should have
a single menu that has 10 menu items with text: 0, 1, . . . , 9, respectively. When a user
selects a number from the menu bar, the corresponding number should be displayed
inside the panel of the window. Once finished, add a key listener. When a user types
a digit between 0 and 9, the digit should be displayed in the window. Create an array
to store the menu items.
*/
package exercise;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
public class exercise_chapter10_5 {
public static void main(String[] args) throws Exception {
MyFrame frame = new MyFrame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
class MyFrame extends JFrame {
MyPanel p;
public MyFrame() {
setSize(300, 300);
JMenuBar bar = new JMenuBar();
setJMenuBar(bar);
//a window with a menu bar
JMenu numbers = new JMenu(" Numbers ");
bar.add(numbers);
// Create an array to store the menu items
ArrayList<JMenuItem> menuitems = new ArrayList<JMenuItem>();
for (int i = 0; i < 10; i++) {
menuitems.add(new JMenuItem(i + ""));
}
for (int i = 0; i < menuitems.size(); i++) {
numbers.add(menuitems.get(i));
}
// add action listener for every menu item
for (int i = 0; i < menuitems.size(); i++) {
menuitems.get(i).addActionListener(new NumberListener(i));
}
p = new MyPanel();
add(p);
}
class NumberListener implements ActionListener {
private int number;
public NumberListener(int num) {
this.number = num;
}
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand());
p.changeNumber(number);
}
}
}
class MyPanel extends JPanel {
private int number;
public void changeNumber(int num) {
this.number = num;
repaint();
}
public MyPanel() {
this.setFocusable(true);
this.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
changeNumber((e.getKeyChar() - '0'));
//System.out.println(e.getKeyChar());
System.out.println("In Panel the number typed is: " + number);
repaint();
}
});
System.out.println("Panel was born");
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
if (e.getButton() == 1) {
System.out.println("current number is: " + number);
repaint();
}
if (e.getButton() == 3) {// right button was pressed
System.out.println("Right mouse button was pressed");
repaint();
}
}
});
}
public void showMessage(String s, Graphics2D g2) {
Font myFont = new Font(" SansSerif ", Font.BOLD + Font.ITALIC, 40);
g2.setFont(myFont);
g2.setColor(Color.RED);
Rectangle2D textBox = myFont.getStringBounds(s, g2.getFontRenderContext());
g2.drawString(s, (int) (getWidth() / 2 - textBox.getWidth() / 2), (int) (getHeight() / 2 - textBox.getHeight()));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
showMessage(Integer.toString(number), g2);
}
}

Thanks for your hints. What worked for me here is that I had to call setFocusable(true) method within JPanel constructor first.
class MyPanel extends JPanel {
private int number;
public void changeNumber(int num) {
this.number = num;
repaint();
}
public MyPanel() {
this.setFocusable(true);
this.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
changeNumber((e.getKeyChar() - '0'));
//System.out.println(e.getKeyChar());
System.out.println("In Panel the number typed is: " + number);
repaint();
}
});
System.out.println("Panel was born");
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
if (e.getButton() == 1) {
System.out.println("current number is: " + number);
repaint();
}
if (e.getButton() == 3) {// right button was pressed
System.out.println("Right mouse button was pressed");
repaint();
}
}
});
}

Basic animation not performing

I am learning java. This is my first animation. I want a ball to move up and down continuously when start button is pressed, and it should STOP when stop button is pressed. The code I have written moves the ball 5 times(3 times down and 2 times up). But the panel displays only start and final positions, it does not display intermediate positions. How to display intermediate positions as well?
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class dabble
{
private boolean z = true;
private int x=10;
private int y=10;
private JFrame frame;
private JLabel label;
private mypanel panel;
private JButton b1;
private JButton b2;
public static void main (String[] args)
{
dabble dab = new dabble();
dab.start();
}
void start()
{
frame = new JFrame();
label = new JLabel();
panel = new mypanel();
b1= new JButton("Start");
b2= new JButton("Stop");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b1.addActionListener(new al1());
b2.addActionListener(new al2());
frame.getContentPane().add(BorderLayout.NORTH,b1);
frame.getContentPane().add(BorderLayout.SOUTH,b2);
frame.getContentPane().add(BorderLayout.CENTER,panel);
frame.getContentPane().add(BorderLayout.EAST,label);
frame.setSize(600,600);
frame.setVisible(true);
}
void go()
{
for(int i=0;i<5;i++)
{
if(z==false)
break;
//label.setText("Hi");
y=510-y;
panel.repaint();
try{
Thread.sleep(500);
//label.setText("sleep");
}catch(Exception Ex)
{
//label.setText("exp");
}
}
}
class al1 implements ActionListener{
public void actionPerformed(ActionEvent event){
go();
}
}
class al2 implements ActionListener{
public void actionPerformed(ActionEvent event){
z=false;
}
}
class mypanel extends JPanel
{
public void paintComponent ( Graphics g)
{
g.setColor(Color.white);
g.fillRect(0,0,this.getWidth(),this.getHeight());
int red = (int) (Math.random()*255);
int green = (int) (Math.random()*255);
int blue = (int) (Math.random()*255);
Color c1 = new Color(red,green,blue);
g.setColor(c1);
g.fillOval(x,y,20,20);
}
}
}

Calling repaint() does not actually paint the panel - it just marks it to be painted later. And painting always happens on the event dispatch thread, as do event listener notifications.
Since go() is being called on the event dispatch thread (by a button action listener), the panel cannot be repainted while go() is running. You simply queue up a single repaint that happens as soon as go() is done.
What you probably want to do is to use a javax.swing.Timer that fires once every 500 ms, and have its action be to move the ball one step and then call repaint().

Well you perform your loop 5 times (instead of an infinite loop). Moreover you change the vertical position from 10 to 500 and then back to 10 etc... If you want to see intermediate position, you should consider asking to repaint the intermediate positions as well providing the intermediate values of y.
OK, doing the following solves your issues but it is definitely a poor design:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class dabble {
private static final long ANIMATION_DURATION = 5000; // 5 seconds
private static final int REFRESH_RATE = 10;// 10 times per second
private boolean incrementing = true;
private volatile boolean z = true;
private int x = 10;
private volatile int y = 10;
private JFrame frame;
private JLabel label;
private mypanel panel;
private JButton b1;
private JButton b2;
public static void main(String[] args) {
dabble dab = new dabble();
dab.start();
}
void start() {
frame = new JFrame();
label = new JLabel();
panel = new mypanel();
b1 = new JButton("Start");
b2 = new JButton("Stop");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b1.addActionListener(new al1());
b2.addActionListener(new al2());
frame.getContentPane().add(BorderLayout.NORTH, b1);
frame.getContentPane().add(BorderLayout.SOUTH, b2);
frame.getContentPane().add(BorderLayout.CENTER, panel);
frame.getContentPane().add(BorderLayout.EAST, label);
frame.setSize(600, 600);
frame.setVisible(true);
}
void go() {
new Animation().start();
}
class al1 implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
go();
}
}
class al2 implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
z = false;
}
}
class mypanel extends JPanel {
#Override
public void paintComponent(Graphics g) {
g.setColor(Color.white);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
int red = (int) (Math.random() * 255);
int green = (int) (Math.random() * 255);
int blue = (int) (Math.random() * 255);
Color c1 = new Color(red, green, blue);
g.setColor(c1);
g.fillOval(x, y, 20, 20);
}
}
class Animation extends Thread {
private long start;
#Override
public void run() {
start = System.currentTimeMillis();
while (true) {
if (!z) {
return;
}
double progress = (double) (System.currentTimeMillis() - start) / ANIMATION_DURATION;
System.err.println(progress);
if (incrementing) {
y = (int) (10 + 500 * progress);
} else {
y = (int) (510 - 500 * progress);
}
if (progress > 1.0) {
start = System.currentTimeMillis();
incrementing = !incrementing;
}
panel.repaint();
try {
Thread.sleep(1000 / REFRESH_RATE);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}

Java: JSplitPane duplicates top panel's contents to bottom panel when Timer is active

So I have a JSplitPane, and two JPanels - one on top, one on the bottom. In both panels I overrode the paintComponent method and added my own graphics. In the bottom panel, I wanted to add an animation. When the panel does not repaint, it's fine, but as soon as the Timer (javax.swing.Timer) starts to call repaints, the bottom panel mimics the appearance of the top panel and glitches out. The actual animations are not refreshed, but rather it keeps on adding (like a dragged paintbrush instead of a moving object).
Here's the code for the Bottom Panel class:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.JPanel;
import javax.swing.Timer;
public class WaitControls extends JPanel {
private int pos;
public WaitControls(){
setBackground(Color.gray);
pos = 0;
}
public void progress(){
//animation timer:
Timer timer = new Timer(30, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
pos++;
repaint();
}
});
timer.start();
}
#Override
public void paintComponent(Graphics g){
g.fillRect(pos, pos, 10, 20);
}
}
And here's the code for the Splitpane class:
//my classes (imported packages)
import rcc.controls.ControlPanel;
import rcc.controls.InitControls;
import rcc.controls.WaitControls;
import rcc.video.Screen;
import javax.swing.JSplitPane;
public class MainPanel extends JSplitPane{
public RCC rcc;
public Screen screen;
private int height;
public ControlPanel curPanel;
public MainPanel(RCC rcc, Screen screen, int height){
super(JSplitPane.VERTICAL_SPLIT);
this.rcc = rcc;
this.screen = screen;
this.height = height;
setDividerSize(2);
setEnabled(false);
setTopComponent(screen);
setToInitControls();
}
//sets the control panel to init controls ***WORKS FINE***
public void setToInitControls(){
InitControls initCtrls = new InitControls(this);
setBottomComponent(initCtrls);
curPanel = initCtrls;
setDividerLocation(height / 4 * 3);
}
//sets the control panel to wait controls (trying to connect) ***GLITCHES***
public void setToWaitControls(){
WaitControls waitCtrls = new WaitControls();
setBottomComponent(waitCtrls);
curPanel = waitCtrls;
setDividerLocation(height / 4 * 3);
waitCtrls.progress();
}
}
The top panel is a bit complicated. It involves mouse action (including a MouseEntered listener) and animates to interact with user mouse input.
The strange thing is, I have another bottom panel that was swapped out that also uses animations, and a timer, and does not have this glitch.
Any ideas what may have caused this? Thank you for all your help!

I can't imagine how your animations works,
1/ but if animation(s) depends of by any of Listener then Timer must be Timer#restart();
2/ check (example), how to pass addNotify()/removeNotify() for start/stop animatiom(s)
NOTE required fullHD monitor for better output or change code line
for (int iPanels = 0; iPanels < 3; iPanels++) {
to
for (int iPanels = 0; iPanels < 2; iPanels++) {
Example:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class AnimationBackground {
public AnimationBackground() {
Random random = new Random();
JFrame frame = new JFrame("Animation Background");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.setLayout(new GridLayout(0, 3, 10, 10));
for (int iPanels = 0; iPanels < 3; iPanels++) {
final MyJPanel panel = new MyJPanel();
panel.setBackground(Color.BLACK);
for (int i = 0; i < 50; i++) {
Star star = new Star(new Point(random.nextInt(490), random.nextInt(490)));
star.setColor(new Color(100 + random.nextInt(155), 100 + random.nextInt(155), 100 + random.nextInt(155)));
star.setxIncr(-3 + random.nextInt(7));
star.setyIncr(-3 + random.nextInt(7));
panel.add(star);
}
panel.setLayout(new GridLayout(10, 1));
JLabel label = new JLabel("This is a Starry background.", JLabel.CENTER);
label.setForeground(Color.WHITE);
panel.add(label);
JPanel stopPanel = new JPanel();
stopPanel.setOpaque(false);
stopPanel.add(new JButton(new AbstractAction("Stop this madness!!") {
private static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
panel.stopAnimation();
}
}));
panel.add(stopPanel);
JPanel startPanel = new JPanel();
startPanel.setOpaque(false);
startPanel.add(new JButton(new AbstractAction("Start moving...") {
private static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
panel.startAnimation();
}
}));
panel.add(startPanel);
frame.add(panel);
}
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
AnimationBackground animationBackground = new AnimationBackground();
}
});
}
class Star extends Polygon {
private static final long serialVersionUID = 1L;
private Point location = null;
private Color color = Color.YELLOW;
private int xIncr, yIncr;
static final int WIDTH = 500, HEIGHT = 500;
Star(Point location) {
int x = location.x;
int y = location.y;
this.location = location;
this.addPoint(x, y + 8);
this.addPoint(x + 8, y + 8);
this.addPoint(x + 11, y);
this.addPoint(x + 14, y + 8);
this.addPoint(x + 22, y + 8);
this.addPoint(x + 17, y + 12);
this.addPoint(x + 21, y + 20);
this.addPoint(x + 11, y + 14);
this.addPoint(x + 3, y + 20);
this.addPoint(x + 6, y + 12);
}
public void setColor(Color color) {
this.color = color;
}
public void move() {
if (location.x < 0 || location.x > WIDTH) {
xIncr = -xIncr;
}
if (location.y < 0 || location.y > WIDTH) {
yIncr = -yIncr;
}
translate(xIncr, yIncr);
location.setLocation(location.x + xIncr, location.y + yIncr);
}
public void setxIncr(int xIncr) {
this.xIncr = xIncr;
}
public void setyIncr(int yIncr) {
this.yIncr = yIncr;
}
public Color getColor() {
return color;
}
}
class MyJPanel extends JPanel {
private static final long serialVersionUID = 1L;
private ArrayList<Star> stars = new ArrayList<Star>();
private Timer timer = new Timer(20, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
for (Star star : stars) {
star.move();
}
repaint();
}
});
public void stopAnimation() {
if (timer.isRunning()) {
timer.stop();
}
}
public void startAnimation() {
if (!timer.isRunning()) {
timer.start();
}
}
#Override
public void addNotify() {
super.addNotify();
timer.start();
}
#Override
public void removeNotify() {
super.removeNotify();
timer.stop();
}
MyJPanel() {
this.setPreferredSize(new Dimension(520, 520));
}
public void add(Star star) {
stars.add(star);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
for (Star star : stars) {
g.setColor(star.getColor());
g.fillPolygon(star);
}
}
}
}