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Graphics Issue with JFrame in a Game Engine

I'm creating a "simple" 2D game engine for the block game Collapse for my college class. I am trying to make it such that the JFrame is resized any time a new screen is introduced, and I have made two attempts at it, one that resizes correctly, but doesn't show anything, and one that shows SOMETHING, but doesn't resize.
For this post, I will be showing the code for the second game engine that I have created, as my first attempt was a monolithic version that I ended up having trouble following myself.
First off, for some reason the window will not close with the X button, even though the setDefaultCLoseOperation(JFrame.EXIT_ON_CLOSE) is enacted.
Second (for the second attempt) the JFrame will not resize, but will show a sliver of the test StartMenu
(sorry for links, editor said I have to have rep of 10 before being able to post pictures... smart move, but still annoying)
http://i1148.photobucket.com/albums/o577/FoxnEagle/GraphicsWindow1_zpscqdgsjqh.png
but upon resizing;
http://i1148.photobucket.com/albums/o577/FoxnEagle/GraphicsWindow2_zpsckr4eohs.png
I guess the question of the post is what am I doing wrong to have the window become unresponsive, and be able to make modern art with it?
Collapse.java
import gameEngine.*;
import screens.*;
import javax.swing.*;
public class Collapse{
private Game game;
public Collapse(){
this.game = new Game("Test", null);
game.getScrMan().setScreen(new StartMenu(game.getScrMan()));
}
public static void main(String[] args){
new Collapse();
}
}
:||package screens||:
StartMenu.java
package screens;
import gameEngine.*;
import java.awt.*;
import javax.swing.*;
public class StartMenu extends Screen{
private final ScreenManager scrMan;
public StartMenu(ScreenManager scrMan){
super(scrMan);
this.scrMan = scrMan;
}
public void onCreate(){
JButton b1 = new JButton();
scrMan.getScrMan().setSize(200, 200);
scrMan.getScrMan().add(b1);
System.out.println("got here");
}
public void onUpdate(){
}
public void onDraw(Graphics2D g2d){
g2d.setColor(Color.BLACK);
g2d.fillOval(10, 10, 10, 10);
}
public void paintComponent(Graphics g){
g.setColor(Color.BLACK);
g.fillOval(10,10,10,10);
}
}
:||package gameEngine||:
Game.java
package gameEngine;
import javax.swing.*;
import java.awt.*;
public class Game{
private final ImageIcon image;
private final String title;
private final GameLoop gameLoop;
private final ScreenManager scrMan;
private final InputManager inpMan;
private final EntityManager entMan;
private JFrame window;
private boolean running;
//constructor and initializer for gameLoop
public Game(String title, ImageIcon image){
this.title = title;
this.image = image;
window = new JFrame();
scrMan = new ScreenManager(this);
inpMan = new InputManager();
entMan = new EntityManager();
gameLoop = new GameLoop(this);
initialize();
SwingUtilities.invokeLater(gameLoop);
}
private void initialize(){
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //close on exit
window.setTitle(title); //set the title
if(image != null){} //set the image icon NOT IMPLEMENTED YET
//window.setResizable(false); //user cannot resize
window.setFocusable(true); //
window.setLocationRelativeTo(null); //put in center of screen
window.add(scrMan); //add the
window.pack();
window.setVisible(true);
running = true;
}
public JFrame getWindow(){return window;}
public boolean getRunning(){return running;}
public ScreenManager getScrMan(){return scrMan;}
public InputManager getInput(){return inpMan;}
public EntityManager getEntMan(){return entMan;}
public void paused(){running = false;}
public void resume(){running = true;}
}
GameLoop.java
package gameEngine;
import java.lang.Runnable;
public class GameLoop implements Runnable{
private final Game game;
private long time;
private final int fps = 30;
public GameLoop(Game game){this.game = game;}
public void run(){
while(true){
while(game.getRunning()){
//System.out.println("running");//debugging
if(game.getScrMan().getScreen() != null){
game.getScrMan().getScreen().onUpdate();
//System.out.println("screen is updating");//debugging
}
//fps clock, commenting out does not fix problem
time = System.currentTimeMillis();
time = (1000/fps) - (System.currentTimeMillis() - time);
if(time > 0){try{Thread.sleep(time);}catch(Exception e){}}
}
}
}
}
ScreenManager.java
package gameEngine;
import javax.swing.JPanel;
import java.awt.*;
public class ScreenManager extends JPanel{
private final Game game;
private Screen screen;
public ScreenManager(Game game){this.game = game;}
public void setScreen(Screen screen){
this.screen = screen;
this.removeAll();
screen.onCreate();
game.getWindow().revalidate();
//game.getWindow().pack();
}
public Screen getScreen(){return screen;}
public Game getGame(){return game;}
public ScreenManager getScrMan(){return this;}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(0,0, 10, 10);
}
}
Screen.java (StartMenu extends and overrides all functions)
package gameEngine;
import java.awt.Graphics;
import java.awt.Graphics2D;
public abstract class Screen{
private final ScreenManager scrMan;
public Screen(ScreenManager scrMan){this.scrMan = scrMan;}
public abstract void onCreate();
public abstract void onUpdate();
public abstract void onDraw(Graphics2D g2d);
}
InputManager.java (nothing implemented yet, just a placeholder)
package gameEngine;
import java.awt.event.*;
public class InputManager implements KeyListener, MouseListener{
public void mouseClicked(MouseEvent event){
}
public void mouseEntered(MouseEvent event){
}
public void mouseExited(MouseEvent event){
}
public void mousePressed(MouseEvent event){
}
public void mouseReleased(MouseEvent event){
}
public void keyPressed(KeyEvent event){
}
public void keyReleased(KeyEvent event){
}
public void keyTyped(KeyEvent event){
}
}
EntityManager.java and Entity.java are just blank classes

This,
SwingUtilities.invokeLater(gameLoop);
runs your game loop in the event dispatch thread, blocking it. So the repaint manager never has a change to draw the contents. You should instead create the GUI in the event dispatch thread, as modifying or creating swing components from other threads is not safe.
The game loop's timing needs to be done in a way that does not block the EDT. The easiest is using a swing Timer; if that proves later to be insufficient, you can switch to another solution, but then you need to pay close attention to thread safety. Swing timer runs the action listener code in the EDT so it's easy to be thread safe that way.

Set JButton to the location of another JButton

I'm trying to move a JButton to the location of another one but the button I want to move moves to a wrong point. My idea is that this happens because I use multiple JPanels. I tried: getLocationOnScreen, getBounds and getLocation, but none of them worked, how to solve it? When an user selects a card on the table or from a player by clicking this card the the target is set, the sender is set by clicking a card from the top panel. playerCardSpotTargetand playerCardSpotSender are both of type Card. When I try to move the for example eight of diamonds this card moves to a point behind the eight and nine of clubs.
Code:
This events belong to the blue cards on the table and the cards for the players(I have to change the name of the event, I know).
private void PlayerOneMouseClicked(java.awt.event.MouseEvent evt){
playerCardSpotTarget=(Card)evt.getSource();
if(playerCardSpotTarget.isBorderPainted()){
playerCardSpotTarget.setBorderPainted(false);
}
else{
playerCardSpotTarget.setBorderPainted(true);
}
}
This event belongs to the cards in the top panel.
private void MouseClicked(java.awt.event.MouseEvent evt) {
playerCardSpotSender=(Card)evt.getSource();
System.out.println(playerCardSpotSender.suit+" "+playerCardSpotSender.kind);
if (playerCardSpotTarget != null && playerCardSpotTarget.isBorderPainted()) {
playerCardSpotSender.setLocation(playerCardSpotTarget.getLocation());
System.out.println(playerCardSpotTarget.getLocationOnScreen());
System.out.println(playerCardSpotSender.getLocationOnScreen());
}
}
Layout for the center panel in the JFrame (BorderLayout.CENTER)
JPanel centerPanelNorth;
JPanel centerPanelCenter;
JPanel centerPanelEast;
JPanel centerPanelSouth;
JPanel centerPanelWest;
JLabel tablePicture;
JPanel centerPanel;
centerPanel=new JPanel(new BorderLayout());
tablePicture = new JLabel(new ImageIcon(this.getClass().getResource(Constants.POKERTABLE_ICON)));
centerPanelNorth=new JPanel();
centerPanelEast=new JPanel();
centerPanelSouth=new JPanel();
centerPanelWest=new JPanel();
centerPanelCenter=new JPanel();
centerPanel.add(centerPanelCenter,BorderLayout.CENTER);
centerPanelCenter.add(tablePicture);
//add
tablePicture.add(boardCard1);
tablePicture.add(boardCard2);
tablePicture.add(boardCard3);
tablePicture.setLayout(new GridBagLayout());
//PLAYER NORTH
centerPanel.add(centerPanelNorth,BorderLayout.NORTH);
centerPanelNorth.add(playerOneCardOne);
centerPanelNorth.add(playerOneCardTwo);
//PLAYER EAST
centerPanel.add(centerPanelEast,BorderLayout.EAST);
centerPanelEast.setLayout(new BoxLayout(centerPanelEast,BoxLayout.X_AXIS));
centerPanelEast.add(playerTwoCardOne);
centerPanelEast.add(playerTwoCardTwo);
//PLAYER SOUTH
centerPanel.add(centerPanelSouth,BorderLayout.SOUTH);
centerPanelSouth.add(playerThreeCardOne);
centerPanelSouth.add(playerThreeCardTwo);
//PLAYER WEST
centerPanel.add(centerPanelWest,BorderLayout.WEST);
centerPanelWest.setLayout(new BoxLayout(centerPanelWest,BoxLayout.X_AXIS));
centerPanelWest.add(playerFourCardOne);
centerPanelWest.add(playerFourCardTwo);
Card.java
public class Card extends JButton{
int suit;
int kind;
boolean known;
String iconPath;
Integer boardPosition;
}

Animating the button movement isn't actually the hardest problem, the hardest problem is trying to move the data about in away in which you can manage it and how to connect the source component with the target...
To start with, you need a means by which you can move a component across container boundaries. While there are probably a few ways to do this, the simplest is to probably use the glass pane of the frame
public class AnimationPane extends JPanel {
public AnimationPane() {
setOpaque(false);
setLayout(null);
}
}
This is nothing special, it's just a JPanel which is transparent and has no layout manager, normally, not recommended, but in the case, we're going to take control..
Now, we need some way to animate the movement...
public enum Animator {
INSTANCE;
private List<IAnimatable> animatables;
private Timer timer;
private Animator() {
animatables = new ArrayList<>(25);
timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
IAnimatable[] anins = animatables.toArray(new IAnimatable[animatables.size()]);
for (IAnimatable animatable : anins) {
animatable.update();
}
}
});
timer.start();
}
public void addAnimatable(IAnimatable animatable) {
animatables.add(animatable);
}
public void removeAnimatable(IAnimatable animatable) {
animatables.remove(animatable);
}
}
public interface IAnimatable {
public void update();
}
public interface IMoveAnimatable extends IAnimatable{
public JComponent getSourceComponent();
public IImportable getImportable();
}
So the Animator is the core "engine", it's basically a Swing Timer which simply calls update on any IAnimatables it might be managing. The intention with this approach is you can have a number of animations running, but it won't degrade the system (greatly) as you only have a single update/timer point.
Now, normally I'd just use something like the Timing Framework or the Trident Framework or even the Universal Tween Engine
The IAnimatable interfaces just define the basic contracts that provide functionality for the animation.
We need to define some kind of contract the defines objects which can take part in the animation process and receive information, or the "target"
public interface IImportable {
public JComponent getView();
public void importValue(String value);
}
public abstract class AbstractImportable extends JPanel implements IImportable {
#Override
public JComponent getView() {
return this;
}
}
Now it occurs to me that we could tap into the pre-existing Transferable API, which would allow you to also implement drag-n-drop (and even copy/cut and paste), this would be used to define a lookup mechanism where you match a given data type with potential targets based on the DataFlavor ... but I'll leave you to investigate how that might work...
The core mechanism basically removes the source component from it's current container, adds it to the AnimationPane, moves the source component across the AnimationPane and then imports the data into the target...
The problem is, you need to translate the location of component from it's current context to the AnimationPane.
A components location is relative to it's parents context. It's relatively easy to do with SwingUtilities.convertPoint(Component, Point, Component)
We calculate the origin point of the source component and the target point, relative to the AnimationPane. We then, on each call to update, calculate the progress of the animation. Instead of using a "delta" movement, we calculate the different between the time we started and a predefined duration (1 second in this case), this generally produces a more flexible animation
public class DefaultAnimatable implements IMoveAnimatable {
public static final double PLAY_TIME = 1000d;
private Long startTime;
private JComponent sourceComponent;
private IImportable importable;
private JComponent animationSurface;
private Point originPoint, destinationPoint;
private String value;
public DefaultAnimatable(JComponent animationSurface, JComponent sourceComponent, IImportable importable, String value) {
this.sourceComponent = sourceComponent;
this.importable = importable;
this.animationSurface = animationSurface;
this.value = value;
}
public String getValue() {
return value;
}
public JComponent getAnimationSurface() {
return animationSurface;
}
#Override
public JComponent getSourceComponent() {
return sourceComponent;
}
#Override
public IImportable getImportable() {
return importable;
}
#Override
public void update() {
if (startTime == null) {
System.out.println("Start");
IImportable importable = getImportable();
JComponent target = importable.getView();
originPoint = SwingUtilities.convertPoint(getSourceComponent().getParent(), getSourceComponent().getLocation(), getAnimationSurface());
destinationPoint = SwingUtilities.convertPoint(target.getParent(), target.getLocation(), getAnimationSurface());
destinationPoint.x = destinationPoint.x + ((target.getWidth() - getSourceComponent().getWidth()) / 2);
destinationPoint.y = destinationPoint.y + ((target.getHeight() - getSourceComponent().getHeight()) / 2);
Container parent = getSourceComponent().getParent();
getAnimationSurface().add(getSourceComponent());
getSourceComponent().setLocation(originPoint);
parent.invalidate();
parent.validate();
parent.repaint();
startTime = System.currentTimeMillis();
}
long duration = System.currentTimeMillis() - startTime;
double progress = Math.min(duration / PLAY_TIME, 1d);
Point location = new Point();
location.x = progress(originPoint.x, destinationPoint.x, progress);
location.y = progress(originPoint.y, destinationPoint.y, progress);
getSourceComponent().setLocation(location);
getAnimationSurface().repaint();
if (progress == 1d) {
getAnimationSurface().remove(getSourceComponent());
Animator.INSTANCE.removeAnimatable(this);
animationCompleted();
}
}
public int progress(int startValue, int endValue, double fraction) {
int value = 0;
int distance = endValue - startValue;
value = (int) Math.round((double) distance * fraction);
value += startValue;
return value;
}
protected void animationCompleted() {
getImportable().importValue(getValue());
}
}
Okay, now this produces a linear animation, which is pretty boring, now if you have plenty of time, you could create an easement like this or just use one of the animation frameworks...
Now, we need to put it together...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
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.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class AnimationTest {
public static void main(String[] args) {
new AnimationTest();
}
public AnimationTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
AnimationPane animationPane = new AnimationPane();
LeftPane leftPane = new LeftPane(animationPane);
RightPane rightPane = new RightPane();
leftPane.setImportabale(rightPane);
rightPane.setImportabale(leftPane);
JFrame frame = new JFrame("Testing");
frame.setLayout(new GridLayout(1, 2));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(leftPane, BorderLayout.WEST);
frame.add(rightPane, BorderLayout.WEST);
frame.setGlassPane(animationPane);
animationPane.setVisible(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class RightPane extends AbstractImportable {
private IImportable source;
private JButton imported;
private String importedValue;
public RightPane() {
setLayout(new GridBagLayout());
setBorder(new LineBorder(Color.DARK_GRAY));
}
public void setImportabale(IImportable source) {
this.source = source;
}
#Override
public void importValue(String value) {
if (imported != null) {
// May re-animate the movement back...
remove(imported);
}
importedValue = value;
imported = new JButton(">> " + value + "<<");
add(imported);
revalidate();
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
public class LeftPane extends AbstractImportable {
private IImportable importable;
public LeftPane(AnimationPane animationPane) {
setLayout(new GridBagLayout());
JButton btn = new JButton("Lefty");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
DefaultAnimatable animatable = new DefaultAnimatable(animationPane, btn, importable, "Lefty");
Animator.INSTANCE.addAnimatable(animatable);
}
});
add(btn);
setBorder(new LineBorder(Color.DARK_GRAY));
}
public void setImportabale(IImportable target) {
this.importable = target;
}
#Override
public void importValue(String value) {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}

Maybe use mousePressed(),when you move the card,you press it until the target.And in the process, you get the information about JButton.getLocation() by the event,and than you need to solve the collision problem between two cards.So it's good!Of course, this is my advice ,you should have better idea!

Java: Repaint in Swing Not Working

I am learning java swing and am having trouble with the following program. It creates a small frame with a quit button at top. The objective is to display coordinates wherever the mouse is clicked. When I click the mouse 2 unwanted things are happening:
the quit button is overridden by the mouse clicks and it no longer responds (instead of responding to event and quitting, it displays coordinates on top of the quit button).
when I click at a new location, the coordinates from the old location persist.
I used removeAll() and revalidate() before doing repaint() based on this discussion but that has not helped. This code is taken from here and the code to says to research online documentation for why this is happening.
Any pointers?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
public class QuitCoordinateTest {
public static void main(String[] args){
GUI gui = new GUI();
}
}
class MyFrame extends JFrame implements ActionListener{
int clickX;
int clickY;
public void paint(Graphics g){
g.drawString("" + clickX + ", " + clickY, clickX, clickY);
}
public void actionPerformed(ActionEvent e){
System.exit(0);
}
}
//=======================================================//
class GUI extends MyFrame {
JButton quitButton = new JButton("Quit");
public GUI(){
MyFrame displayWindow = new MyFrame();
displayWindow.setTitle("Title");
/*
JPanel buttonPanel = new JPanel();
buttonPanel.add(quitButton);
displayWindow.getContentPane().add(buttonPanel,BorderLayout.NORTH);
JPanel textPanel = new JPanel();
*/
displayWindow.getContentPane().add(quitButton,BorderLayout.NORTH);
quitButton.addActionListener(displayWindow);
displayWindow.setSize(201,201);
displayWindow.setVisible(true);
// displayWindow.pack();
displayWindow.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
displayWindow.addMouseListener(new MouseProc(displayWindow));
}//end constructor
}//end class GUI definition
//=======================================================//
//This listener class monitors for mouse presses and
// displays the coordinates of the mouse pointer when the
// mouse is pressed on the source object.
class MouseProc extends MouseAdapter{
MyFrame refToWin;
MouseProc(MyFrame inWin){
refToWin = inWin;
}
//Override the mousePressed method to determine and
// display the coordinates when the mouse is pressed.
public void mousePressed(MouseEvent e){
refToWin.removeAll();
refToWin.clickX = e.getX();
refToWin.clickY = e.getY();
//Force the JFrame object to be repainted in order to
// display the coordinate information.
refToWin.removeAll();
refToWin.validate();
refToWin.repaint();
}
}

repaint() is working fine.
Avoid drawing directly on the JFrame.
Instead draw in the protected void paintComponent(Graphics g) method override of a JPanel that is then displayed in your JFrame.
Be sure to call the super's paintComponent(g) method inside of your paintComponent override -- this will erase the old images and is the reason for one of your problems.
Use reasonable comments in your code. Too many comments and too much text distracts and makes understanding your code harder, not easier.
Calling removeAll() on your JFrame will do just that -- remove all components including your button. Why are you calling this? Are you sure that you want to call this method?
A minor nitpick -- you'll want to avoid directly setting the fields of another class, such as your clickX and clickY fields. Instead, make them private, and only allow outside classes to modify them through public methods. While it may not matter much for this small program, it will matter greatly when you start scaling up your programming and create large programs with complex interactions. The key to success here will be to limit and control all communication between classes to avoid hard to detect side effects.
For example, something like...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
For example
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class DetectClicks extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = 650;
private int clickX;
private int clickY;
public DetectClicks() {
MyMouseListener mouseAdapter = new MyMouseListener(this);
addMouseListener(mouseAdapter);
addMouseMotionListener(mouseAdapter); // to allow dragging!
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
private static void createAndShowGui() {
DetectClicks mainPanel = new DetectClicks();
JFrame frame = new JFrame("DetectClicks");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyMouseListener extends MouseAdapter {
private DetectClicks detectClicks;
public MyMouseListener(DetectClicks detectClicks) {
this.detectClicks = detectClicks;
}
#Override
public void mousePressed(MouseEvent evt) {
showPoint(evt);
}
#Override
public void mouseDragged(MouseEvent evt) {
showPoint(evt);
}
private void showPoint(MouseEvent evt) {
detectClicks.setClickX(evt.getX());
detectClicks.setClickY(evt.getY());
detectClicks.repaint();
}
}

Your event is getting consumed by the handler that prints the coordinates, you need to redispatch the event so that the button can see it. You can do it like this, inside the coordinate display event handler:
Component c = e.getComponent();
c.getParent().dispatchEvent( e );
Also, I'd be tempted to use the glass pane of the frame, and put a JLabel on it with the co-ordinates rather than messing with the paint method.

you don't have to use any of repaint(),invalidate() etc.
i highly recommend to use
SwingUtilities.invokeLater(new Runnable() {
public void run() {
//TODO udpdate UI compontents, layouts etc.
}
});
this guarantees that UI components update on real time. Because we don't know when the system update UI hierarchy so we can't force it. This allow system to determine by it's self.

Update JFrame paintings

I want to update my rectangle when my key is pressed currently I have almost achieved that
package com.raggaer.frame;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
public class Elements extends JPanel {
private static int y = 250;
public Elements() {
this.getInputMap().put(KeyStroke.getKeyStroke("UP"), "up");
this.getActionMap().put("up", new Listener("up"));
this.getInputMap().put(KeyStroke.getKeyStroke("DOWN"), "down");
this.getActionMap().put("down", new Listener("down"));
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(250, this.y, 10, 10);
}
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
public static void setY(int cord) {
y += cord;
// Cant access repaint()
}
}
And this is my listener class
package com.raggaer.frame;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.AbstractAction;
public class Listener extends AbstractAction {
private String code;
//final Elements game = new Elements();
public Listener(String order) {
this.code = order;
}
public void actionPerformed(ActionEvent e) {
System.out.println(this.code);
Elements.setY(1);
}
}
Currently everything works except that I dont know how to update the y position of the rectangle, I tried using an static variable but then I cant call the repaint() method.

No,.... don't use static anything, neither methods nor fields because if you do this, you'll break object-oriented programming rules, leaving your code difficult to update and maintain. The exception of course would be your main method, and carefully chosen fields and methods who truly belong to the class. Instead give the class that needs to call the Element object's method a valid reference to the object whose state you wish to change, the drawing JPanel or Element object. This can be done by passing in a valid reference via a constructor parameter.
public class Listener extends AbstractAction {
private Elements elements;
public Listener(Elements elements) {
this.elements = elements;
}

Manual Positioning of Image in JFrame

I am trying to create a JFrame that displays an image from a file path onto a particular position on the JFrame. At a later time (when a button is clicked), I want the image to move positions, say, 50 pixles to the left. If a layout manager is necessary, I want to use the null layout, as this is a project for myself and I am not quite ready to learn how to write my own layout manager.
So far, I have managed to display a BufferedImage in a frame, but I do not know how to specify its position.
Is using a BufferedImage even the correct approach? What is the best way to go about doing this?
Update: I tried to follow your suggestion of using mouselistener and it resulted in this:
class ImgComponent extends JComponent implements ChangeListener, MouseListener {
MovableImage mi;
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
mi.addListener1(this);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(mi.i, mi.getX(), mi.getY(), null);
}
#Override
public void stateChanged(ChangeEvent e) {
repaint();
}
#Override
public void mouseClicked(MouseEvent e) {
mi.setPos(100, 100);
System.out.println("yay");
}
}
But unfortinely, the mouseClicked event never triggers. I just want that damn image to move, lol.

Here's a complete example that uses the model/view/controller pattern. (Just dump all snippets after each other in a single .java file.)
import java.awt.*;
import java.awt.event.ActionEvent;
import java.util.*;
import java.util.List;
import javax.swing.*;
import javax.swing.event.*;
// A class encapsulating an image and a x-coordinate (a "model")
class MovableImage {
Image i = new ImageIcon("duke.png").getImage();
private int x = 0;
// Observers that are interested in movements.
List<ChangeListener> listeners = new ArrayList<ChangeListener>();
public void addListener(ChangeListener cl) {
listeners.add(cl);
}
public int getX() {
return x;
}
public void incrementX() {
x += 10;
// Notify those interested.
for (ChangeListener cl : listeners)
cl.stateChanged(null);
}
}
// A graphical component displaying the model.
// Object of this class are interested in movement because when the image moves,
// this component needs to be repainted.
class ImgComponent extends JComponent implements ChangeListener {
// The movable image to present.
MovableImage mi;
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(mi.i, mi.getX(), 10, null);
}
// This method is called from MovableImage when the position changes.
#Override
public void stateChanged(ChangeEvent e) {
repaint();
}
}
// Main class.
public class FrameTestBase extends JFrame {
public static void main(String args[]) {
// Create the "model".
final MovableImage mi = new MovableImage();
FrameTestBase t = new FrameTestBase();
t.setLayout(new BorderLayout());
// Add a component presenting the model.
t.add(new ImgComponent(mi), BorderLayout.CENTER);
// Create a button which increments x when clicked on.
t.add(new JButton(new AbstractAction("Move right") {
#Override
public void actionPerformed(ActionEvent e) {
mi.incrementX();
}
}), BorderLayout.SOUTH);
// Show it.
t.setDefaultCloseOperation(EXIT_ON_CLOSE);
t.setSize(400, 400);
t.setVisible(true);
}
}
Regarding your edit:
You need to add the mouse listener as well. In the constructor:
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
mi.addListener1(this);
}
add the following line at the bottom:
addMouseListener(this);