Develop Reference

Previous instances of characters are not erased

It's like if you were in a mirror maze, you might have trouble finding one specific reflections of yourself. So you would have multiple reflections of yourself, confusing you when you try to find that direct reflection of yourself.
Sadly I cannot post an image..........
So...
Character is "C"
It goes from
C
to
C C
when I attempt to move right.
package WASD;
import java.awt.Color;
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.*;
public class WASD extends JFrame implements KeyListener, ActionListener{
private int playerX = 400;
private int playerY = 400;
int C = 1;
private int RESTART = 0; // Three ENTER = Restart
private Timer timer;
JFrame j = new JFrame();
private int previousX = -50;
private int previousY = -50;
public WASD() {
JPanel panel = new JPanel();
setTitle("Not supposed to be a painting program.");
setSize(2000, 2000);
timer = new Timer(8, this);
this.getContentPane().add(panel);
addKeyListener(this);
setVisible(true);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String[] args){
WASD W = new WASD();
}
public void paint(Graphics g) { //TODO paint is only working once, then failing forever.
//////////////////////////
g.setColor(Color.BLACK);
g.drawRect(0, 0, 3000, 3000); // Background
if(C == 1) g.setColor(Color.RED);
else if (C == 2) g.setColor(Color.BLUE);
else if (C == 3) g.setColor(Color.GREEN);
else if (C == 4) g.setColor(Color.YELLOW);
else if(C>4){
g.setColor(Color.GRAY);
try {
Thread.sleep(1000); //Gray pauses for a second I guess...
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
C = 1;
}
g.fillRect(playerX, playerY, 50, 50); // Player/
g.setColor(Color.BLACK);
g.fillRect(previousX, previousY, 50, 50);
g.dispose(); //Last thing
}
#Override
public void actionPerformed(ActionEvent e) {
timer.start();
repaint();
}
#Override
public void keyPressed(KeyEvent K) {
// TODO Auto-generated method stub
int e = K.getKeyCode();
repaint(); //timer.start(); does not affect this. g.dispose() is unavailable.
/*
If this repaint is used, then the previous locations
that the player was at will be painted as well.
Basically, instead of moving, all instances
made will not be deleted. #PaintingApplication
However, if it is not used, then the CHARACTER will not move at all.
It seems that the problem is not about
playerX, or playerY,
instead, it is about the program not refreshing.
*/
if((e == KeyEvent.VK_RIGHT || e == KeyEvent.VK_D) && playerX<2000){
playerX += 200;
}
else if((e == KeyEvent.VK_LEFT || e == KeyEvent.VK_A) && playerX>0){
playerX -= 200;
}
else if((e == KeyEvent.VK_UP || e == KeyEvent.VK_W) && playerY>0){
playerY -= 200;
}
else if(e == KeyEvent.VK_DOWN || e == KeyEvent.VK_S && playerY<2000){ // Easter egg bug 1
playerY += 200;
}
else if (e == KeyEvent.VK_C){
C++;
}
else if(e == KeyEvent.VK_ENTER){
if(RESTART == 3){
playerX = 400;
playerY = 400;
RESTART = 0; //TODO
repaint();
}
else{
RESTART++;
}
}
else{
RESTART = 0;
}
}
#Override public void keyTyped(KeyEvent arg0) {}
#Override public void keyReleased(KeyEvent arg0) {}
}

I apologize for making such a simple mistake. The problem is in the function "paint". The line
g.drawRect(0, 0, 3000, 3000); //Outline of Rectangle
should be
g.fillRect(0, 0, 3000, 3000); //Actually filling the background.

Java 'Background' opens to small to see anything

I am making a game and the game window will only open to the size of the title. Please let me know what changes I need to make the "b.setSize(900,885)" work. I will change or add any amount of code if needed.
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.*;
public class Background extends JFrame implements KeyListener, ActionListener{
int platform1X = 300, platform1Y = 555, platform2X, platform2Y;
Image image;
public boolean isJumping = false;
int playerx = 100, playery = 585, velX = 0, velY = 0;
public boolean[] keyDown = new boolean[4];
private int fallingSpeed = 0;
private int gravity = 5;
private int jumpPower = -30;
public Background(){
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
keyDown[0] = false;
keyDown[1] = false;
keyDown[2] = false;
keyDown[3] = false;
}
public void paint(Graphics g){
if(!isOnGround()){
fall();
}
ImageIcon i = new ImageIcon("/Users/kairotieremorton/Documents/java code/Kairo and Enoch Game/src/images/Backgroundsquareman.png");
image = i.getImage();
g.drawImage(image, 0, 0, 900, 700, null);
g.setColor(Color.BLUE);
g.fillRect(platform1X, platform1Y, 120, 20);
g.setColor(Color.RED);
g.fillRect(playerx, playery, 30, 30);
try {
Thread.sleep(40);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
repaint();
playery = playery + velY;
playerx = playerx + velX;
}
public static void main(String[] args){
Background b = new Background();
b.setTitle("Game");
b.setSize(900,885);
b.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b.setVisible(true);
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if(isOnGround() && key == KeyEvent.VK_SPACE){
keyDown[0] = true;
jump();
}
//if(key == KeyEvent.VK_DOWN){ setvelY(5); keyDown[1] = true;}
if(key == KeyEvent.VK_LEFT) { setvelX(-5); keyDown[2] = true;}
if(key == KeyEvent.VK_RIGHT) { setvelX(5); keyDown[3] = true;}
System.out.println(key);
System.out.println(playerx);
System.out.println(playery);
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_SPACE){ keyDown[0] = false;} //tempObject.setVelY(0);
//if(key == KeyEvent.VK_DOWN) keyDown[1] = false;//tempObject.setVelY(0);
if(key == KeyEvent.VK_LEFT) keyDown[2] = false;//tempObject.setVelX(0);
if(key == KeyEvent.VK_RIGHT) keyDown[3] = false; //tempObject.setVelX(0);
//vertical movement
if(!keyDown[0]) setvelY(0); System.out.println(isOnGround());
//horizontal movement
if(!keyDown[2] && !keyDown[3]) setvelX(0);
}
public void keyTyped(KeyEvent e) {}
public void actionPerformed(ActionEvent e) {
//playery = playery + velY;
//playerx = playerx + velX;
//repaint();
}
public boolean isOnGround(){
if(playery + (30 /2) >= 585) {
return true;
}
return false;
}
public void fall(){
playery = playery + fallingSpeed;
fallingSpeed = fallingSpeed + gravity;
}
public void jump(){
fallingSpeed = jumpPower;
fall();
}
public void setvelX(int velX) {
this.velX = velX;
}
public void setvelY(int velY) {
this.velY = velY;
}
public float getvelX(){
return velX;
}
public float getvelY(){
return velY;
}
public int getplayerx(){
return playerx;
}
public int getplayery(){
return playery;
}
public void setplayerx(int playerx) {
this.playerx = playerx;
}
public void setplayery(int playery) {
this.playery = playery;
}
public Rectangle getBounds(){
return new Rectangle(getplatform1X(), platform1Y(), 120, 20);
}
public int getplatform1X(){
return platform1X;
}
public int platform1Y(){
return platform1Y;
}
public Rectangle getBoundsTop(){
return new Rectangle(getplayerx() + 10, getplayery(), 30 - 20, 5);
}
public Rectangle getBoundsBottom(){
return new Rectangle(getplayerx() + 10, getplayery() + 30 - 5, 30 - 20, 5);
}
public Rectangle getBoundsLeft(){
return new Rectangle(getplayerx(), getplayery()+10, 5, 30 -20);
}
public Rectangle getBoundsRigth(){
return new Rectangle(getplayerx() + 30 - 5, getplayery()+10, 5, 30 - 20);
}
}

Okay, that took a lot of looking, but...
public Rectangle getBounds() {
return new Rectangle(getplatform1X(), platform1Y(), 120, 20);
}
is your problem. JFrame#getBounds is a method used by JFrame to return the position and the size of the component and since you've overridden it, it will now ignore any values you pass to setSize (directly or indirectly)
Have a read of the following for reasons why you shouldn't override paint of top level containers like JFrame
How can I set in the midst?
Graphics rendering in title bar
Java JFrame .setSize(x, y) not working?
How to get the EXACT middle of a screen, even when re-sized
As a general rule of thumb, you should avoid extending from JFrame, as you're not really adding any new functionality to the class, it locks you into a single use case and, based on your experience, can cause other problems.
You should start with something like JPanel and override its paintComponent method instead (and make sure you call super.paintComponent before you do any custom painting)
Take a look at Painting in AWT and Swing and Performing Custom Painting
You paint methods should run as fast as possible, so you should avoid loading resources like loading images, within the paint method
Swing is single threaded, so calling Thread.sleep in the paint method will cause the entire program to stop, including it's ability to respond to new events from the user.
I'd also discourage you from using KeyListener, using the key bindings API will be more reliable. Take a look at How to Use Key Bindings for more details

Edit:
A better way to achieve the same result is to call b.setPreferredSize(dimension); and then pack() your frame.
See this answer for more information about JFrame.pack() :
https://stackoverflow.com/a/22982334/5224040
Try this in your main method:
public static void main(String[] args) {
Background b = new Background();
Dimension d = new Dimension(900, 885); //Create a new Dimension
b.setTitle("Game");
b.setPreferredSize(d); //Set the PreferredSize;
b.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b.pack(); //Pack the frame
b.setVisible(true); //Setting Visible
}
You can also use the following methods to reposition your frame as necessary:
b.setLocationRelativeTo(null); //center the location on the screen.
b.setLocation(0, 0); //Set location explicitly
Call either of these methods below b.pack(); to reposition your frame.

Image location does not change in response to key events

package testapplication;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
public class TestApplication extends JFrame implements Runnable {
int sizex = 800;
int sizey = 650;
int x, y, xDirection, yDirection;
private Image dbImage;
private Graphics dbg;
Image character;
#Override
public void run(){
try{
while(true){
move();
Thread.sleep(5);
}
}
catch(Exception e){
System.out.println("ERROR!!!");
}
}
public void move(){
x += xDirection;
y += yDirection;
if(x <= 0)
x = 0;
if(x >= 778)
x = 778;
if(y <= 22)
y = 22;
if(y >= 628)
y = 628;
}
public void setXDirection(int xdir){
xDirection = xdir;
}
public void setYDirection(int ydir){
yDirection = ydir;
}
Font font = new Font("Arial", Font.BOLD, 30);
public class AL extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
//Key press inputs "WASD"
if(keyCode == KeyEvent.VK_W) {
setYDirection(-1);
}
if(keyCode == KeyEvent.VK_A) {
setXDirection(-1);
}
if(keyCode == KeyEvent.VK_S) {
setYDirection(+1);
}
if(keyCode == KeyEvent.VK_D) {
setXDirection(+1);
}
//end Key press inputs "WASD"
}
#Override
public void keyReleased(KeyEvent e) {
int keyCode = e.getKeyCode();
//Key release inputs "WASD"
if(keyCode == KeyEvent.VK_W) {
setYDirection(0);
}
if(keyCode == KeyEvent.VK_A) {
setXDirection(0);
}
if(keyCode == KeyEvent.VK_S) {
setYDirection(0);
}
if(keyCode == KeyEvent.VK_D) {
setXDirection(0);
}
//end Key release inputs "WASD"
}
}
public TestApplication() {
//Load images
ImageIcon i = new ImageIcon("C:/Users/Min/Documents/NetBeansProjects/TestApplication/src/testapplication/Untitled-1.png") {};
character = i.getImage();
//Game properties
addKeyListener(new AL());
setTitle("TestApplication");
setSize(sizex, sizey);
setResizable(false);
setVisible(true);
setBackground(Color.LIGHT_GRAY);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
x = 30;
y = 628;
}
#Override
public void paint(Graphics g) {
dbImage = createImage(getWidth(), getHeight());
dbg = dbImage.getGraphics();
paintComponent(dbg);
g.drawImage(dbImage, 0, 0, this);
}
public void paintComponent(Graphics g) {
g.setFont(font);
g.setColor(Color.RED);
g.drawString("Welcome to TESTTEST", 300,125);
g.setColor(Color.RED);
g.drawImage(character, x, y, this);
repaint();
}
public static void main(String[] args) {
TestApplication ta = new TestApplication();
//Threads
Thread t1 = new Thread();
t1.start();
}
}
In my Java code, there is supposed to be an image that moves using the WASD keys. The image shows, yet it will not move. What's wrong?
This is a simple Java code that is supposed to make an image roam around the window with WASD keys. I am not sure what I did wrong in the code, I've double checked and everything looked fine...

First of all, if you need to change the image location while the user presses one of the wsda keys then you need to add 1 and -1 to the current value of x and y ( image location). You just set 1 and -1 which will move the image just one pixel even if, for example, you press the d button multiple times over and over.
You need to change method setXDirection to this (I have added a plus before the equal sign to add xDir value to whatever xDirection is.)
public void setXDirection(int xDir)
{
xDirection += xDir
}
Make the same correction with yDirection (yDirection += yDir)
Second, you don't call your paint method. You have to call it each time your user presses a key (one of wasd ofcourse), so do it at the final line of your keyReleased method.
I hope these two correct your code but I think you need to recheck the code again with much care.
Good luck,
Iman

You forgot to add the Runnable instance to the Thread constructor.
Your main method should be:
public static void main(String[] args) {
TestApplication ta = new TestApplication();
//Threads
Thread t1 = new Thread(ta);
t1.start();
}

creating many objects with collision properties. JAVA

I have a simple program with three rectangles: one that can move with the push of the arrow keys, and two that are already moving back and forth on their own.
When the 'player' rectangle and top red collide, the player driven rectangle gets put back to (0,0). When I try to collide the player rectangle with the bottom red rectangle, it does not have those collision properties and I have no idea why.
What am I missing?
import java.awt.*;//needed for graphics
import javax.swing.*;//needed for JFrame window
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class javaapplication23 extends JFrame implements KeyListener, ActionListener {
public static int x = 0;
public static int y = 0;
public static int x2 = 100;
public static int y2 = 100;
public javaapplication23() {//constructor for JPanel
add(new JP());
}//close Jpanel Contructor
public static void main(String[] args) {
javaapplication23 w = new javaapplication23();
w.setTitle("MIKE IS AWESOME");
w.setSize(Toolkit.getDefaultToolkit().getScreenSize());
w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
w.setVisible(true);
w.addKeyListener(w);
}
public class JP extends JPanel {//start JPanel CLass
public JP() {
Container c = getContentPane();
c.setBackground(Color.white);//backgraund color can be changed
}
public void paint(Graphics g) {//opens paint method
super.paint(g);
player(g, x, y);
g.setColor(Color.RED);
enemylevel1(g, x2, y2);
Rectangle enemyblocks = new Rectangle(x2, y2, 25, 25);
Rectangle player = new Rectangle(x, y, 25, 25);
enemyblocks.contains(x2, y2);
player.contains(x, y);
if (player.getBounds().intersects(enemyblocks.getBounds())) {
x = 0;
y = 0;
}
pause(1);
repaint();
}//close paint method
}//close JPanel Class
public static void pause(int time) {
try //opens an exception handling statement
{
Thread.sleep(time);
} catch (InterruptedException e) {
} //captures the exception
}
public void actionPerformed(ActionEvent e) {
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == e.VK_RIGHT) {
x += 20;//global variable controlling right movement
repaint();
}
if (e.getKeyCode() == e.VK_LEFT) {
x -= 20;//global variable controlling left movement
repaint();
}
if (e.getKeyCode() == e.VK_UP) {
y -= 20;//global variable controlling up movement
repaint();
}
if (e.getKeyCode() == e.VK_DOWN) {
y += 20;//global variable controlling down movement
repaint();
}
}
public void player(Graphics g, int x, int y) {
g.fillRect(x, y, 30, 30);
}
public void enemylevel1(Graphics g, int x, int y) {
g.fillRect(x2, y2, 25, 25);
g.fillRect(x2, y2 + 100, 25, 25);
if (x2 < 200 && y2 == 100) {
x2 += 1;
}
if (x2 == 200 && y2 >= 100) {
y2 += 1;
}
if (x2 <= 200 && y2 >= 101) {
x2 -= 1;
}
if (x2 == 100 && y2 <= 101) {
y2 -= 1;
}
pause(10);
repaint();
}
}

Start by having a look at Working with Geometry, this will allow you to reduce much of the code complexity.
Basically, a enemy is just a Rectangle, Graphics2D can paint these without to much of an issue. What you need to do is create an instance which can also update it's position based on your needs
public class Enemy extends Rectangle {
private int xDelta;
public Enemy(int x, int y) {
super(x, y, 20, 20);
if (x == 0) {
xDelta = 1;
} else {
xDelta = -1;
}
}
public void update(Rectangle bounds) {
x += xDelta;
if (x < bounds.x) {
x = bounds.x;
xDelta *= -1;
} else if (x > bounds.x + bounds.width - width) {
x = bounds.x + bounds.width - width;
xDelta *= -1;
}
}
}
So, this creates a single unit of work, which is isolated from everything else and carries it's own logic with it. This makes updating it, painting and generally working with much simpler.
Next, you need to create a List of these
public class Bounce extends JPanel implements KeyListener, ActionListener {
private List<Enemy> enemies;
//...
public Bounce() {
enemies = new ArrayList<>(5);
int y = 100;
for (int index = 0; index < 5; index++) {
int x = (index % 2 == 0) ? 0 : 200;
Enemy enemy = new Enemy(x, y);
enemies.add(enemy);
y += 60;
}
This creates a List of Enemys which are distributed evenly within the container.
Now, we need to paint them....
#Override
protected void paintComponent(Graphics g) {//opens paint method
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g.create();
g2d.setColor(Color.RED);
for (Enemy enemy : enemies) {
g2d.fill(enemy);
}
}//close paint method
nb: General convention suggests that you should override paintComponent when you want to perform custom painting
But they don't move, that kind of sucks. So we need a way to, on a regular bases, update the position of the enemies...
First, we create a simple method which we can call to update the enemies, remember, they are capable of updating themselves, we just need to tell them when
public void updateState() {
Rectangle bounds = new Rectangle(20, 20, 200, 200);
for (Enemy enemy : enemies) {
enemy.update(bounds);
}
}
Remember, the Enemy is self contained, it knows how to update itself based on the constraints you have provided.
And now, we need to call this method on a regular bases...
javax.swing.Timer timer = new javax.swing.Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
updateState();
repaint();
}
});
timer.start();
Okay, this will schedule a callback every 40 milliseconds which will allow us to call the updateState method and repaint the component. This is neat because it won't block the Event Dispatching Thread (making our program look like it's hung) but which notifies us within the context of the EDT, making it safe to update the UI from within - WIN/WIN :)
Take a look at Concurrency in Swing and How to use Swing Timers for more details.
Okay, but that doesn't solve the collision...
The player is also a Rectangle, so why not use the same concept we have with the enemies...
public class Bounce extends JPanel implements KeyListener, ActionListener {
private List<Enemy> enemies;
private Rectangle player;
//...
public Bounce() {
player = new Rectangle(0, 0, 30, 30);
enemies = new ArrayList<>(5);
//...
}
#Override
protected void paintComponent(Graphics g) {//opens paint method
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
drawPlayer(g2d);
g2d.setColor(Color.RED);
for (Enemy enemy : enemies) {
g2d.fill(enemy);
if (player.intersects(enemy)) {
player.x = 0;
player.y = 0;
}
}
}//close paint method
public void drawPlayer(Graphics2D g) {
g.fill(player);
}
Which ends up with something like...
This allows you to add/remove enemies as you want and also change the way in which the enemies move, simply and easily
An my "awesome" test code...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Bounce extends JPanel implements KeyListener, ActionListener {
private List<Enemy> enemies;
private Rectangle player;
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 Bounce());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public Bounce() {
player = new Rectangle(0, 0, 30, 30);
enemies = new ArrayList<>(5);
int y = 100;
for (int index = 0; index < 5; index++) {
int x = (index % 2 == 0) ? 0 : 200;
Enemy enemy = new Enemy(x, y);
enemies.add(enemy);
y += 60;
}
setBackground(Color.white);//backgraund color can be changed
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
updateState();
repaint();
}
});
timer.start();
setFocusable(true);
requestFocusInWindow();
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
requestFocusInWindow();
}
});
addKeyListener(this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(240, 400);
}
#Override
protected void paintComponent(Graphics g) {//opens paint method
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
drawPlayer(g2d);
g2d.setColor(Color.RED);
for (Enemy enemy : enemies) {
g2d.fill(enemy);
if (player.intersects(enemy)) {
player.x = 0;
player.y = 0;
}
}
}//close paint method
public void actionPerformed(ActionEvent e) {
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == e.VK_RIGHT) {
player.x += 20;//global variable controlling right movement
}
if (e.getKeyCode() == e.VK_LEFT) {
player.x -= 20;//global variable controlling left movement
}
if (e.getKeyCode() == e.VK_UP) {
player.y -= 20;//global variable controlling up movement
}
if (e.getKeyCode() == e.VK_DOWN) {
player.y += 20;//global variable controlling down movement
}
}
public void drawPlayer(Graphics2D g) {
g.fill(player);
}
public void updateState() {
Rectangle bounds = new Rectangle(20, 20, 200, 200);
for (Enemy enemy : enemies) {
enemy.update(bounds);
}
}
public class Enemy extends Rectangle {
private int xDelta;
public Enemy(int x, int y) {
super(x, y, 20, 20);
if (x == 0) {
xDelta = 1;
} else {
xDelta = -1;
}
}
public void update(Rectangle bounds) {
x += xDelta;
if (x < bounds.x) {
x = bounds.x;
xDelta *= -1;
} else if (x > bounds.x + bounds.width - width) {
x = bounds.x + bounds.width - width;
xDelta *= -1;
}
}
}
}

Cant understand how to get this collision detection to work what am i doing wrong?

I need help trying to sort how this collision detection in my code.
Here is my code and I have had a little assistance from various sources online but nothing with a definite explanation to it yet, but all in all I have made a lot of progress. So basically a quick thank you internet.
What I have to do is make a game where I control an object, in this case a blue circle and then touch another on screen object, in this case a yellow circle and when they touch the yellow circle will dissapear and the word "YUM" will take its place then the yellow circle will move randomly to a new location.
This is a lot like the game snake but I can't get the collision to work right and also if I did have it working I have no idea how I would update the location to a new location randomly on the screen.
here is the code:
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Random;
import javax.swing.JFrame;
import org.w3c.dom.css.Rect;
public class javagame2 extends JFrame {
private Image dbimage;
private Graphics dbg;
Font font = new Font("Arial", Font.BOLD, 30);
static Random generator = new Random();
static int randomIndex0 = generator.nextInt(900);
static int randomIndex1 = generator.nextInt(400);
public static class player
{
static int x = 150;
static int y = 150;
static final int Width = 50;
static final int Height = 50;
}
public static class pizza
{
static final int x1 = randomIndex0;
static final int y1 = randomIndex1;
int Width = 50;
int Height = 50;
public boolean intercepts(player p) {
// TODO Auto-generated method stub
return false;
}
}
public class AL extends KeyAdapter
{
public void keyPressed(KeyEvent e)
{
int keycode = e.getKeyCode();
if(keycode == e.VK_LEFT){
if(player.x <= 0)
{
player.x = 0;
}
else
{
player.x += -10;
}
}
if(keycode == e.VK_RIGHT){
if(player.x >= 950)
{
player.x = 950;
}
else
{
player.x += 10;
}
}
if(keycode == e.VK_UP){
if(player.y <= 20)
{
player.y = 20;
}
else
{
player.y += -10;
}
}
if(keycode == e.VK_DOWN){
if(player.y >= 450)
{
player.y = 450;
}
else
{
player.y += 10;
}
}
}
public void keyReleased(KeyEvent e){}
}
public int getX()
{
return player.x;
}
public int getY()
{
return player.y;
}
/*
public boolean collide(pizza f)
{
if(f.X <= (player.x+40) && f.Y >= (player.y+40))
{
System.out.println("they collided");
return true;
}
else
{
return false;
}
}
*/
public boolean collide(pizza f, player p)
{
if(f.x1 <= p.x && f.y1 >= p.y)
{
System.out.println("they collided");
return true;
}
else
{
return false;
}
}
public javagame2()
{
addKeyListener(new AL());
setTitle("Ballon Popper");
setSize(1000, 500);
setResizable(false);
setVisible(true);
setBackground(Color.BLACK);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paintcomponent(Graphics g)
{
g.setColor(Color.WHITE);
g.drawRect(pizza.x1, pizza.y1, 50, 50);
g.setFont(font);
g.setColor(Color.RED);
g.drawString("Eat the Pizza!", 350, 50);
g.setColor(Color.BLUE);
g.drawRect(getX(), getY(), 50, 50);
g.fillOval(getX(), getY(), 50, 50);
g.setColor(Color.YELLOW);
g.fillOval(pizza.x1, pizza.y1, 50, 50);
repaint();
}
public void paint(Graphics g)
{
dbimage = createImage(getWidth(), getHeight());
dbg = dbimage.getGraphics();
paintcomponent(dbg);
g.drawImage(dbimage, 0, 0, this);
}
public static void main(String arg[])
{
new javagame2();
}
}
Here is the updated code I just worked out a little bit, it does run but I'm a bit confused on how to go about removing the yellow circle once I have touched or even what to do, I tried using .intersects but that didn't seem to do anything.

I don't know java, but this seems straightforward.
Two circles collide when the distance between their centers is less than the sum of their radii. (And if the circles are the same size, we needn't worry about whether their "locations" are actually at their centers or not.)
public boolean collide(pizza f, player p)
{
if(Math.pow(f.x1-p.x, 2) + Math.pow(f.y1-p.y, 2) <= Math.pow(f.Width/2 + p.Width/2, 2))
{
System.out.println("they collided");
return true;
}
else
{
return false;
}
}