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Smooth transition between moving left and right [duplicate]

I am trying to get a circle to move through the input of a keyboard. I am not able to move the object at all. Can someone help me figure out what is wrong? Here is my code:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JPanel;
public class AlienInvader extends JPanel implements KeyListener{
Constants constant = new Constants();
public void update() {
constant.x += constant.xvel;
addKeyListener(this);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.MAGENTA);
g.fillOval(constant.x, constant.y, 30, 30);
repaint();
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println(constant.x);
switch(e.getKeyCode()) {
case KeyEvent.VK_LEFT:
constant.xvel = -1;
break;
case KeyEvent.VK_RIGHT:
constant.xvel = 1;
break;
}
}
#Override
public void keyReleased(KeyEvent e) {
switch(e.getKeyCode()) {
case KeyEvent.VK_LEFT:
constant.xvel = -1;
break;
case KeyEvent.VK_RIGHT:
constant.xvel = 1;
break;
}
}
#Override
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
}
I am not sure what I am doing wrong. I thought it was because I wasn't calling the update method, but when I added a if statement in paintComponent (so it only calls itself once) and tried it, I had no luck.

To start with, don't call repaint within any paintXxx method. Paint methods are typically called in response to a call to repaint, therefore you are creating a nasty, never ending, ever consuming loop of resource hell.
Secondly, KeyListeners only respond to key events when 1- The component the are registered to are focusable 2- When the component they are registered to have focus.
They are a poor choice in this case. Use Key bindings instead
Thirdly, you are not providing a preferredSize hint for layout managers to use. This may or may not be a bad thing in your case, but it's possible that you component will be laid out with a size of 0x0
Example
Something like....
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MoveCircle {
public static void main(String[] args) {
new MoveCircle();
}
public MoveCircle() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private int xDelta = 0;
private int keyPressCount = 0;
private Timer repaintTimer;
private int xPos = 0;
private int radius = 10;
public TestPane() {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "pressed.left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "pressed.right");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), "released.left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "released.right");
am.put("pressed.left", new MoveAction(-2, true));
am.put("pressed.right", new MoveAction(2, true));
am.put("released.left", new MoveAction(0, false));
am.put("released.right", new MoveAction(0, false));
repaintTimer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
xPos += xDelta;
if (xPos < 0) {
xPos = 0;
} else if (xPos + radius > getWidth()) {
xPos = getWidth() - radius;
}
repaint();
}
});
repaintTimer.setInitialDelay(0);
repaintTimer.setRepeats(true);
repaintTimer.setCoalesce(true);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.drawOval(xPos, 0, radius, radius);
g2d.dispose();
}
public class MoveAction extends AbstractAction {
private int direction;
private boolean keyDown;
public MoveAction(int direction, boolean down) {
this.direction = direction;
keyDown = down;
}
#Override
public void actionPerformed(ActionEvent e) {
xDelta = direction;
if (keyDown) {
if (!repaintTimer.isRunning()) {
repaintTimer.start();
}
} else {
repaintTimer.stop();
}
}
}
}
}
For example...

Dr java keylistener help object move after key is released

I'm trying to create a program where an object continuously falls down the screen unless the user is pressing space, in which case it moves up. So far I've gotten the object to initially start falling when I run the program. When I press space, the object moves up (like it should). But, when I release the key the object stops moving. I want it to continue falling when the key is released.
I've looked at using key bindings instead of keylistener but I've had trouble with it. I am a highschool student looking to major in computer science so forgive me for not knowing too many advanced coding terms/methods. However, I am one of the best in my class and a fast learner who is eager to solve this problem. Here is my code:
public class htestnew extends JPanel implements ActionListener, KeyListener {
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public htestnew() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon background = new ImageIcon("OBJECTEXAMPLE1");
background.paintIcon(this, g, 0, 0);
}
public void actionPerformed(ActionEvent e) {
if (y < 0)
{
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 0;
//I have tried setting this value to 1 but it does not work
}
If it is easier to use keybindings a personal and easy to follow example would be amazing. Thank you.

So, changing...
public void keyReleased(KeyEvent e) {
vely=0;
//I have tried setting this value to 1 but it does not work
}
to...
public void keyReleased(KeyEvent e) {
vely=1;
//I have tried setting this value to 1 but it does not work
}
Basically made it work (after I added in something that actually paints)
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test extends JPanel implements ActionListener, KeyListener {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 1;
//I have tried setting this value to 1 but it does not work
}
}
I would strongly recommend that you take a look at How to Use Key Bindings instead of using KeyListener, it will solve the core problem with KeyListener
Key Binding Example...
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test extends JPanel implements ActionListener {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyBinding("space.pressed", KeyEvent.VK_SPACE, true, new ChangeYAction(-1));
addKeyBinding("space.released", KeyEvent.VK_SPACE, false, new ChangeYAction(1));
}
protected void addKeyBinding(String name, int virtualKey, boolean pressed, Action action) {
addKeyBinding(name, KeyStroke.getKeyStroke(virtualKey, 0, !pressed), action);
}
protected void addKeyBinding(String name, KeyStroke keyStroke, Action action) {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(keyStroke, name);
am.put(name, action);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public class ChangeYAction extends AbstractAction {
private int changeYTo;
public ChangeYAction(int changeYTo) {
this.changeYTo = changeYTo;
}
#Override
public void actionPerformed(ActionEvent e) {
vely = changeYTo;
}
}
}

JLabel not showing up no matter what I do

I have tried a ton of different things to try to get the JLabel to show but I don't understand why it is not working. I have tried resizing it, though that is not what i want to do, I have tried other classes, but I would prefer to stick with this one, and it is starting to get really frustrating. If you have any ideas please help. But please try to keep them simple and explain very clearly as I am still quite new to java. I have only been going for about three or four months. Here is my code:
package com.thefallenpaladin;
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
/**
* Created by darkp_000 on 11/4/2015.
*/
#SuppressWarnings("serial")
public class Game extends JPanel implements KeyListener,MouseListener {
public boolean mainMenu = true;
public int winWidth = 700; //Window Stats
public int winHeight = 600;
public int buttonOneX = 60; // Button Stats
public int buttonOneY = 240;
public int buttonOneW = 100;
public int buttonOneH = 75;
public boolean buttonOne = false;
public int mouseX; // not set because it is set in mouseClicked
public int mouseY;
public static void main(String[] args) {
Game game = new Game();
JFrame window = new JFrame("I hate this");
JLabel onePlayer = new JLabel();
onePlayer.setLocation(0,0/*game.buttonOneX + game.buttonOneX/2,game.buttonOneY + game.buttonOneY/2*/);
window.add(game);
window.setFocusable(true);
window.setResizable(false);
window.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
window.setSize(700,600); //TODO
window.setVisible(true);
game.requestFocusInWindow();
game.add(onePlayer);
game.addKeyListener(game);
game.addMouseListener(game);
window.setLocationRelativeTo(null);
while(true) { // Main Game loop
onePlayer.setText("One Player");
game.repaint();
game.customUpdate();
}
}
public void customUpdate() {
if(mouseX > buttonOneX && mouseX < buttonOneX+buttonOneX && mouseY > buttonOneY && mouseY < buttonOneY+buttonOneY && mainMenu) {
buttonOne = true;
System.out.print("Starting Game");
}
}
public void paint(Graphics g) {
if(mainMenu) {
g.setColor(Color.CYAN); // Set main menu
g.fillRect(0,0,winWidth,winHeight);
g.setColor(Color.GREEN);
g.fillRect(buttonOneX,buttonOneY,buttonOneW,buttonOneH);
}
if(buttonOne) {
mainMenu = false;
g.setColor(Color.GREEN);
g.fillRect(0,0,winWidth,winHeight);
}
}
public void keyTyped(KeyEvent e) {
}
public void keyPressed(KeyEvent e) {
System.out.println(e);
}
public void keyReleased(KeyEvent e) {
}
public void mouseClicked(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
// System.out.println(e);
mouseX = e.getX();
mouseY = e.getY();
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
}

Okay so you've made a couple of basic mistakes...
First, JLabel onePlayer = new JLabel(); creates an empty label, with no size (0x0) and since labels are transparent by default, you'd not see it
Next, you've overridden paint of a top level container (JFrame), but failed to honor the paint chain effectively preventing any of the child components from ever getting painted
public void paint(Graphics g) {
if (mainMenu) {
g.setColor(Color.CYAN); // Set main menu
g.fillRect(0, 0, winWidth, winHeight);
g.setColor(Color.GREEN);
g.fillRect(buttonOneX, buttonOneY, buttonOneW, buttonOneH);
}
if (buttonOne) {
mainMenu = false;
g.setColor(Color.GREEN);
g.fillRect(0, 0, winWidth, winHeight);
}
}
So, if I remove your paint method and change JLabel onePlayer = new JLabel(); to JLabel onePlayer = new JLabel("I'm a label"); I get this output...
Also...
while (true) { // Main Game loop
onePlayer.setText("One Player");
game.repaint();
game.customUpdate();
}
has the potential to try screw up your program, you have no guarantee's in what thread your main method is been called and you should not make assumptions.
Start by creating a custom component, extending from something like JPanel and override it's paintComponent method, place your custom painting there. In fact, you should have a panel for each state of your game (menu, running, settings, etc).
Add these to your frame (probably using a CardLayout to enable you to easily switch between them)
Use either a Thread or Swing Timer as a main game loop, one which you create explicitly.
Have a look at Painting in AWT and Swing, Performing Custom Painting, How to Use CardLayout and How to use Swing Timers for some more details
As a "conceptual" example...
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
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.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class AwesomeGame {
public static void main(String[] args) {
new AwesomeGame();
}
public AwesomeGame() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new ContentPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public interface NavigationController {
public void letsPlay();
}
public class ContentPane extends JPanel implements NavigationController {
private CardLayout cardLayout;
private GamePane gamePane;
public ContentPane() {
cardLayout = new CardLayout();
setLayout(cardLayout);
add(new MenuPane(this), "TheMenu");
add((gamePane = new GamePane()), "TheGame");
cardLayout.show(this, "TheMenu");
}
#Override
public void letsPlay() {
cardLayout.show(this, "TheGame");
gamePane.play();
}
}
public class MenuPane extends JPanel {
public MenuPane(NavigationController navigationController) {
JLabel label = new JLabel("My Super Dupa Awesome Game!");
label.setFont(label.getFont().deriveFont(Font.BOLD, 48));
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(label, gbc);
JButton play = new JButton("Play Now!");
play.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
navigationController.letsPlay();
}
});
add(play, gbc);
setBackground(Color.GREEN);
}
}
public class GamePane extends JPanel {
public GamePane() {
setBackground(Color.BLUE);
}
public void play() {
Timer timer = new Timer(500, new ActionListener() {
int count;
#Override
public void actionPerformed(ActionEvent e) {
count++;
if (count % 2 == 0) {
setForeground(Color.BLACK);
} else {
setForeground(Color.RED);
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
String text = "I bet you're blowen away by it's awesomness!";
FontMetrics fm = g2d.getFontMetrics();
int x = (getWidth() - fm.stringWidth(text)) / 2;
int y = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();
g2d.drawString(text, x, y);
g2d.dispose();
}
}
}

Repaint without painting every component again

i have an application containing a jframe, this jframe then adds a jpanel which constains an image. the jpanel is displayed for a given time, then removed from the jframe and another jpanel is added.
I want to fade in and out between the images, and ive done this using a timer
private void fadeOut() {
ActionListener fadeOutAc = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
opacity += 10;
if (opacity >= 255) {
opacity = 255;
fadeOutT.stop();
}
repaint();
}
};
fadeOutT = new Timer(20, fadeOutAc);
fadeOutT.start();
}
private void fadeIn() {
ActionListener fadeInAc = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
opacity -= 10;
if (opacity <= 0) {
opacity = 0;
fadeInT.stop();
}
repaint();
}
};
fadeInT = new Timer(10, fadeInAc);
fadeInT.setInitialDelay(200);
fadeInT.start();
}
public void paint(Graphics g) {
super.paintComponent(g);
g.setColor(new Color(picColor.getRed(), picColor.getGreen(), picColor.getBlue(), opacity));
g.fillRect(0, 0, presWin.getWidth(), presWin.getHeight());
}
i recently moved the fading in/out from the jpanel to the jframe instead. The problem is, that in the jpanel, the repaint only had to draw an image, now it has to repaint the entire jpanel each time. Is there a way to call repaint without having the paint the components, only the rectangel?

To me, it seems a bit silly to put the functionality in the JFrame when what you seem to want is a container which can fade it's content in and out. This way you can isolate the responsibility to a single container/class which can be placed or used in what ever way you want in isolation to the rest of the UI.
Basically, this example uses a FadingPane (based on a JPanel) to control the fading process, but onto which I place JLabel which holds the actual images.
Fading is controlled through the use of a AlphaComposite, meaning that this panel will actually physically fade in and out, not just change fill color ;)
There is also a FadingListener which provides additional notifications about the fading process, really only interested in fadeOutDidComplete, so you can switch the images and fade the panel back in, but you never know...
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel label;
private FadingPane fadingPane;
private File[] pictures;
private int index;
public TestPane() {
// Just for show
setBackground(Color.RED);
fadingPane = new FadingPane(new FadeListener() {
#Override
public void fadeDidStart(FadingPane panel) {
}
#Override
public void fadeDidStop(FadingPane panel) {
}
#Override
public void fadeOutDidComplete(FadingPane panel) {
nextPicture();
fadingPane.fadeIn();
}
#Override
public void fadeInDidComplete(FadingPane panel) {
}
});
setLayout(new BorderLayout());
fadingPane.setLayout(new BorderLayout());
label = new JLabel();
fadingPane.add(label);
add(fadingPane);
JButton next = new JButton("Next");
add(next, BorderLayout.SOUTH);
next.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
fadingPane.fadeOut();
}
});
pictures = new File("/Volumes/Disk02/Dropbox/MegaTokyo/thumnails").listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
String name = pathname.getName().toLowerCase();
return name.endsWith(".jpg") || name.endsWith(".png");
}
});
nextPicture();
}
protected void nextPicture() {
index++;
if (index >= pictures.length) {
index = 0;
}
try {
BufferedImage img = ImageIO.read(pictures[index]);
label.setIcon(new ImageIcon(img));
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
public interface FadeListener {
public void fadeDidStart(FadingPane panel);
public void fadeDidStop(FadingPane panel);
public void fadeOutDidComplete(FadingPane panel);
public void fadeInDidComplete(FadingPane panel);
}
public class FadingPane extends JPanel {
private float delta;
private float alpha = 1f;
private Timer timer;
private FadeListener fadeListener;
public FadingPane(FadeListener fadeListener) {
this.fadeListener = fadeListener;
// This is important, as we may not always be opaque
// and we don't want to stuff up the painting process
setOpaque(false);
timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
float alpha = getAlpha() + delta;
if (alpha < 0.001f) {
alpha = 0f;
timer.stop();
fadeListener.fadeOutDidComplete(FadingPane.this);
} else if (alpha >= 1.0f) {
alpha = 1.0f;
timer.stop();
fadeListener.fadeInDidComplete(FadingPane.this);
}
setAlpha(alpha);
}
});
}
public float getAlpha() {
return alpha;
}
public void setAlpha(float value) {
if (alpha != value) {
this.alpha = Math.min(1.0f, Math.max(0.0f, value));
repaint();
}
}
#Override
public void paint(Graphics g) {
// I don't normally recomamned overriding paint, but in this case,
// I want to affect EVERYTHING that might be added to this panel
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(getAlpha()));
super.paint(g2d);
g2d.dispose();
}
public void fadeIn() {
timer.stop();
fadeListener.fadeDidStop(FadingPane.this);
delta = 0.05f;
timer.restart();
fadeListener.fadeDidStart(FadingPane.this);
}
public void fadeOut() {
timer.stop();
fadeListener.fadeDidStop(FadingPane.this);
delta = -0.05f;
timer.restart();
fadeListener.fadeDidStart(FadingPane.this);
}
}
}

Thats totaly normal, moving your function to the JFrame and calling repaint function would actualy call repaint of your JFrame.
I think the best solution would be to pass panel as an argument to your fadeIn and fadeOut function and call its repaint methode for example fadeIn :
private void fadeIn(JPanel panelParam) {
ActionListener fadeInAc = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
opacity -= 10;
if (opacity <= 0) {
opacity = 0;
fadeInT.stop();
}
panelParam.repaint(); // here call repaint of the panel.
}
};
fadeInT = new Timer(10, fadeInAc);
fadeInT.setInitialDelay(200);
fadeInT.start();
}
With that you can apply your effect on any other panel.
Hope it helped.

Java graphic not painting properly

I've written the following code
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
final public class Test
{
JFrame frame;
DrawPanel drawPanel;
boolean up = false;
boolean down = true;
boolean left = false;
boolean right = true;
private int timeStep = 0;
private int ballYTravel = 100;
private int BALL_NUM = 24;
public static void main(String... args)
{
new Test().go();
}
private void go()
{
frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
drawPanel = new DrawPanel();
frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
frame.setResizable(false);
frame.setSize(800, 600);
frame.setLocationByPlatform(true);
frame.setVisible(true);
moveIt();
}
class DrawPanel extends JPanel
{
private static final long serialVersionUID = 1L;
public double getY(int i, int t) {
return 200 + ballYTravel / 2 * (Math.sin(timeStep * (i / 200 + 0.08)));
}
public void paintComponent(Graphics g)
{
for (int k = 0; k < BALL_NUM; k++ ) {
g.fillRect(100 + 20 *k , (int) getY(k, timeStep), 6, 6);
}
timeStep++;
}
}
private void moveIt()
{
while (true)
{
try
{
Thread.sleep(10);
}
catch (Exception e)
{
e.printStackTrace();
}
frame.repaint();
}
}
}
It runs and animates, however it is not animating in the same fashion as the Javascript code I referenced it from which can be found here http://codepen.io/anon/pen/ZYQoQZ
any help in understanding why is appreciated

There are (possibly) two basic problems...
In getY, you are ignoring the parameter t and using timeStep instead, while, technically, this probably isn't going to make a MASSIVE difference, it is an area of concern
You have an integer division issue. i/200 will result in int result, where you really want a double. Change it to i/200d
For example...
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
final public class Test {
private int timeStep = 0;
private final int ballYTravel = 100;
private final int BALL_NUM = 24;
public static void main(String... args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DrawPanel());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
class DrawPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawPanel() {
new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
timeStep++;
repaint();
}
}).start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 200);
}
public double getY(int i, int t) {
return 100 + ballYTravel / 2 * (Math.sin(t * (i / 200d + 0.08)));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
for (int k = 0; k < BALL_NUM; k++) {
g.fillRect(10 + 20 * k, (int) getY(k, timeStep), 6, 6);
}
}
}
}
You're also breaking the paint chain, which is going to cause you issues in the long run, make sure you are calling super.paintComponent...
For more details see...
Performing Custom Painting
Painting in AWT and Swing
Concurrency in Swing
How to use Swing Timers
Initial Threads

Your transliteration reveals several problems:
Swing GUI objects should be constructed and manipulated only on the event dispatch thread.
Don't use setSize() when you really mean to override getPreferredSize().
Invoke pack() to let the container adopt its preferred size.
Use javax.swing.Timer to pace the animation.
Revised code, incorporating #Mad's fix and using drawOval():
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
final public class Test {
JFrame frame;
DrawPanel drawPanel;
private int timeStep = 0;
private int ballYTravel = 100;
private int BALL_NUM = 24;
public static void main(String... args) {
new Test().go();
}
private void go() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
drawPanel = new DrawPanel();
frame.add(BorderLayout.CENTER, drawPanel);
frame.setResizable(false);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
Timer t = new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
drawPanel.repaint();
}
});
t.start();
}
});
}
private class DrawPanel extends JPanel {
public double getY(int i, int t) {
return 200 + ballYTravel / 2 * (Math.sin(t * (i / 200d + 0.08)));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
for (int k = 0; k < BALL_NUM; k++) {
g.drawOval(100 + 20 * k, (int) getY(k, timeStep), 8, 8);
}
timeStep++;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(700, 500);
}
}
}