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Java Drawing Multiple Squares in Same JFrame

I am trying to make an animation with multiple thread. I want to paint n squares where this n comes from commend-line argument. Every square has their x-y coordinates, colors and speed. They are moving to the right of the frame with different speed, color and coordinates. Since I am using multi thread I assume I have to control each squares. So I have to store each square object in the ArrayList. However, I am having trouble with painting those squares. I can paint one square but when I try to paint multiple squares, it does not show. Here what I have done so far:
DrawSquare.java
import java.awt.Graphics;
import javax.swing.JPanel;
public class DrawSquare extends JPanel {
public Square square;
public DrawSquare() {
square = new Square();
}
#Override
public void paintComponents(Graphics g) {
// TODO Auto-generated method stub
super.paintComponents(g);
}
#Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
super.paint(g);
g.setColor(square.getC());
g.fillRect(square.getX(), square.getY(), square.getR(), square.getR());
}
}
Square.java
import java.awt.Color;
import java.util.Random;
public class Square {
private int x,y,r,s;
private Color c;
private Random random;
public Square() {
random = new Random();
x = random.nextInt(100) + 30;
y = random.nextInt(100) + 30;
r = random.nextInt(50) + 20;
s = random.nextInt(20) + 5;
c = new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255));
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getR() {
return r;
}
public int getS() {
return s;
}
public Color getC() {
return c;
}
}
Animation.java
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Animation extends JFrame implements Runnable {
private JPanel panel;
private DrawSquare square;
public Animation() {
}
public static void main(String[] args) {
Animation w = new Animation();
DrawSquare square = new DrawSquare();
JFrame f = new JFrame("Week 9");
int n = Integer.parseInt(args[0]);
f.setVisible(true);
f.setSize(700,700);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setResizable(false);
for(int i=0; i<n; i++) {
f.getContentPane().add(square);
}
}
#Override
public void run() {
// TODO Auto-generated method stub
}
}

So, starting with...
public class DrawSquare extends JPanel {
public Square square;
public DrawSquare() {
square = new Square();
}
#Override
public void paintComponents(Graphics g) {
// TODO Auto-generated method stub
super.paintComponents(g);
}
#Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
super.paint(g);
g.setColor(square.getC());
g.fillRect(square.getX(), square.getY(), square.getR(), square.getR());
}
}
As general recommendation, it's preferred to put custom painting in the paintComponent method (note, there's no s at the end)
When paint is called, the Graphics context has already been translated to the component coordinate position. This means that 0x0 is the top/left corner of the component, this also means that...
g.fillRect(square.getX(), square.getY(), square.getR(), square.getR());
is painting the rect at x + x x y + y, which will, at the very least, paint the rect in the wrong position, at worst paint it beyond the visible scope of the component.
You're also not providing any sizing hints for the component, so it's default size will be 0x0, which prevent it from been painted.
Since I am using multi thread I assume I have to control each squares.
Well, since I can't really see what's driving the animation, I imagine that when you say "multi thread" you're suggesting that each square has it's own Thread. In this case, that's a bad idea. Let's put aside the thread synchronisation issues for a moment, more threads doesn't equate to more work you can do, at some point, it will begin to degrade the system performance.
In most cases, a single, well managed thread, is all you really need. You also have to understand that Swing is NOT thread safe. This means that you shouldn't update the UI (or states that the UI relies on) from outside the context of the Event Dispatching Thread.
So, while you're thread can update the position of the rects, you need to take care to ensure that they are not been painted while they are been update. Once you've updated the state, you then need to trigger a paint pass (which is trivial in of itself)
So I have to store each square object in the ArrayList.
Yep, good start
However, I am having trouble with painting those squares. I can paint one square but when I try to paint multiple squares, it does not show.
Okay, so instead of using multiple components, use one. Run through your ArrayList within the paintComponent method of this component and paint all the rects to it. This provides a much simpler way to manage things like bounds detection, as you have only one container to worry about.
I'd highly recommend you have a look at:
Java Bouncing Ball which demonstrates many of the concepts discussed here
Concurrency in Swing
How to use Swing Timers
Performing Custom Painting
Painting in AWT and Swing

Java Mousepress() to draw images

I create this to draw a fish when the mouse is pressed at the mouse's x and y coordinate. but i seems then that the drawfish method is not being called. I can't find the reason why is it is not working. I would be me very grateful for any help.
/*FishTank*/
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
/*FishTank class-contains a frame and the WinstonCanvas.*/
public class FishTank{
public static void main ( String[] args ){
javax.swing.SwingUtilities.invokeLater(new Runnable(){
public void run(){
JFrame window = new JFrame();
window.setTitle("Fish Tank");
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setBounds(30, 30, 700, 430);
window.getContentPane().add(new FishTankCanvas());
window.setVisible(true);
}
});
}
}
/*FishTankCanvas is a component that allows drawing shapes.*/
class FishTankCanvas extends JComponent {
static Graphics2D g;
int x = 11;
Timer myTimer;
public FishTankCanvas(){
myTimer = new Timer (2, new ActionListener(){
public void actionPerformed (ActionEvent evt){
repaint();
}
});
myTimer.start();
}
public void paint(Graphics graphics) {
g = (Graphics2D)graphics;
//makes the background white
Color backgroundColor = new Color(89, 216, 255);//light blue
g.setColor(backgroundColor);
g.fillRect(0,0,this.getWidth(),this.getHeight());
// drawfish (Graphics graphics, int bodyX, int bodyY, int bodyLength,int bodyHeight, int tailwidth, int eyesize,int tailcolor, int bodycolor)
// Mouselistener and mouseadapter
this.addMouseListener (new MouseAdapter() {
public void mousePressed(MouseEvent e) {
//call drawfish method
drawfish(FishTankCanvas.g,e.getX(), e.getY(),118,74,1,((int) (Math.random()*(4 - 0))));
repaint();
}
});
// x coordinate plus 1 of fish (animate)
x= x + 1;
}
// drawfish method
public void drawfish(Graphics graphics, int bodyX, int bodyY, int bodyLength,int bodyHeight,int tailcolor, int bodycolor ){
Graphics2D g = (Graphics2D)graphics;
bodyX +=x;
//colours
Color[] colours= new Color[5];
colours[0] = new Color(0, 0, 0);//black
colours[1] = new Color(162, 0, 255);//purple
colours[2] = Color.red;//red
colours[3] = new Color(255,255,0);// yellow
colours[4] = new Color(60,179,113);//green
//draw fish
// body
g.setColor(colours[bodycolor]);
g.fillOval(bodyX, bodyY, bodyLength, bodyHeight);
// tail
g.setColor(colours[tailcolor]);
int tailWidth = bodyLength/4;
int tailHeight = bodyHeight/2;
int[] tailPointx = new int[3];
int[] tailPointy = new int[3];
tailPointx[0]=bodyX;
tailPointy[0]=bodyY+bodyHeight/2;
tailPointx[1]=bodyX-tailWidth;
tailPointy[1]=bodyY+bodyHeight/2-tailHeight;
tailPointx[2]=bodyX-tailWidth;
tailPointy[2]=bodyY+tailHeight+tailHeight;
g.fillPolygon(tailPointx, tailPointy, 3);
// eye
g.setColor(colours[0]);
g.fillOval(bodyX+3*bodyLength/4, bodyY+bodyHeight/2-bodyHeight/5, bodyHeight/5, bodyHeight/5);
}
}

i seems then that the drawfish method is not being called.
Well that is easy enough to verify. All you need to do is add debug code to the method to determine if this is true or not. Then you can tell us if that is the problem instead of guessing.
Other problems:
Don't add the MouseListener to the component in a painting method. The listener should be added in the constructor of your class.
Don't override paint(). Custom painting is done by overriding the paintComponent() method. And don't forget to invoke super.paintComponent(...).
Extend JPanel instead of JComponent. Then you can just use the setBackground() method to paint the background.
However, the real problem is that when you click the mouse the fish might get drawn, but then the Timer does a repaint which will clear the panel 2ms later, so you never really see the fish. Get rid of the Timer. There is no need for the Timer to draw a fish.
Assuming you want to paint multiple fish you need to keep track of every place you click and then paint all the fish. The two way of doing this are:
Keep an ArrayList of the points where you want to paint the fish and then iterate through this list in your painting method
Paint the fish on a BufferedImage when the mouse click happens, and then just paint the image.
See Custom Painting Approaches for working examples of both of these approaches.

What code should I add so that the rectangles previously printed persist,instead of getting erased when the new rectangles are painted?

What code should I add so that the rectangles painted before continue to exist on the screen when new ones are printed.Here is the code
import javax.sound.midi.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class MiniMusicPlayer3
{
private boolean fire = false;
private JFrame frame;
public static void main(String args[])
{
MiniMusicPlayer3 mini = new MiniMusicPlayer3();
mini.go();
}
public void go()
{
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600,600);
frame.setVisible(true);
MyDrawPanel boxes = new MyDrawPanel();
frame.getContentPane().add(boxes);
try
{
Sequencer player =MidiSystem.getSequencer();
player.open();
Sequence seq = new Sequence(Sequence.PPQ,4);
Track track = seq.createTrack();
int arr[] ={127};
player.addControllerEventListener(new MyDrawPanel(),arr);
//add notes to the track
for(int i = 5;i<61;i+=4)
{
track.add(makeEvent(144,1,i,100,i));
track.add(makeEvent(176,1,127,0,i));
track.add(makeEvent(128,1,i,100,(i+2)));
}
player.setSequence(seq);
player.setTempoInBPM(220);
player.start();
}
catch(Exception ex)
{
}
}
public MidiEvent makeEvent(int onOff,int one,int note,int vel,int tick)
{
MidiEvent event = null;
try
{
ShortMessage a = new ShortMessage();
a.setMessage(onOff,one,note,vel);
event = new MidiEvent(a,tick);
}
catch(Exception e)
{
}
finally
{
return event;
}
}
class MyDrawPanel extends JPanel implements ControllerEventListener
{
public void controlChange(ShortMessage message)
{
System.out.println("control change happens");
fire = true;
frame.repaint();
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if(fire)
{
Graphics2D g2d = (Graphics2D)g;
int red = (int)(Math.random()*255);
int blue = (int)(Math.random()*255);
int green = (int)(Math.random()*255);
Color color = new Color(red,blue,green);
g2d.setColor(color);
int height = (int)((Math.random()*120)+10);
int width = (int)((Math.random()*120)+10);
int x = (int)((Math.random()*40)+10);
int y = (int)((Math.random()*40)+10);
g2d.fillRect(x, y, width, height);
fire = false;
}
}
}
}
Also why does the code above not let the rectangles persist as opposed to the code below that allows the circles to persist
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Animate
{
private JFrame frame;
private int x=10,y=10;
public static void main(String args[])
{
Animate ballRoll = new Animate();
ballRoll.go();
}
public void go()
{
frame = new JFrame();
frame.setSize(500,500);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
MyRoll ball = new MyRoll();
frame.getContentPane().add(ball);
for(x = 5;x<=350;x++)
{
y=x;
try
{
Thread.sleep(50);
}
catch(Exception e)
{
System.out.println("dsfsd");
}
ball.repaint();
}
}
class MyRoll extends JPanel
{
public void paintComponent(Graphics g)
{
g.setColor(Color.ORANGE);
g.fillOval(x, y, 100, 100);
}
}
}

Replace frame.repaint() with this.repaint() and remove super.paintComponent(g) if you want to persist the previous painting as well but I never suggest you to use this approach. You have to redraw all the objects again in paintComponent().
Please have a look at below sections for detail information about Paint processing in Swing application.
Painting in AWT and Swing
The Paint processing
A Closer Look at the Paint Mechanism

"What code should I add so that the rectangles previously printed persist,instead of getting erased when the new rectangles are painted?"
Create a list of Rectangle2D object (as a class member).
Loop through the list in the paintComponent and paint each rectangle.
When you want to add a new rectangle, well, add a new rectangle to the list and repaint.
If you want different colors (or and other state) for each rectangle, create a wrapper like (See some of the examples below).
"Also why does the code above not let the rectangles persist as opposed to the code below that allows the circles to persist"
No rectangle are not "persisting" per se. What you are seeing are paint artifacts from not calling super.paintComponent which clears the previous paint. You should always call super.paintComponent though, like in your first example. So your best options is to go with the first part of my answer.
See a bunch of examples here and here and here and here and here and here.
The basic premise of all those examples is storing a list of similar object in a list and iterating through the list to paint all the objects. Each object can have its own specific state.

You could also extend your MyDrawPanel class so you keep track of which rectangles to paint plus their colors. So you could add each new rectangle to a list of rectangles and keep track of the rectangle colors using a map. Then you just need to add new rectangles to the list and the new color to the map. Finally, you'll need to loop through the list of rectangles and paint these one by one.
Here is how it could be done:
class MyDrawPanel extends JPanel implements ControllerEventListener
{
// List of all rectangles that needs to be painted
java.util.List<Rectangle> rectangles = new ArrayList<Rectangle>();
// Map over all colors for each rectangle that must be painted
Map<Rectangle, Color> rectangleColors = new HashMap<Rectangle, Color>();
public void controlChange(ShortMessage message)
{
System.out.println("control change happens");
fire = true;
frame.repaint();
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if(fire)
{
Graphics2D g2d = (Graphics2D)g;
int red = (int)(Math.random()*255);
int blue = (int)(Math.random()*255);
int green = (int)(Math.random()*255);
Color color = new Color(red,blue,green);
g2d.setColor(color);
int height = (int)((Math.random()*120)+10);
int width = (int)((Math.random()*120)+10);
int x = (int)((Math.random()*40)+10);
int y = (int)((Math.random()*40)+10);
// Create a new rectangle to paint
Rectangle newRect = new Rectangle(x, y, width, height);
// Store the rectangle in the list over rectangles to paint
rectangles.add(newRect);
// Add the color of the rectangle in the map over rectangle colors
rectangleColors.put(newRect, color);
// Paint all the rectangles using their colors one by one
for (Rectangle rect : rectangles) {
// Get the color of the rectangle
Color rectColor = rectangleColors.get(rect);
// Set the rectangle color
g2d.setColor(rectColor);
// Fill the rectangle with the rectangle color
g2d.fill(rect);
}
fire = false;
}
}
}

There are two common approaches:
as has already been mentioned a couple of times, you keep a List of objects to paint and then iterate through the List in the paintComponent(...) method.
draw to a BufferedImage.
Take a look at Custom Painting Approaches which exams both of these approaches and contains working examples of both.

How to delete an JPanel Object?

Im on to create a little "game", something like an 2d AirForce Shooter.
So, i have a problem with deleting unused enemys.
An Enemy is an simple JPanel, which is saved in the main logic as an array List.
public static ArrayList<Enemy> enemys = new ArrayList<Enemy>();
The Enemy run logic does the following:
while(!destroyed){
if(Game.running){
x--;
if(getBounds().intersects(Field.player.getBounding())){
Player.death = true;
}
if(x < 0){
Field.deleteEnemy(this);
}
setBounds((int) x, (int) y, 100, 50);
try{Thread.sleep(10);}catch(InterruptedException e){}
}
}
So you can seem there i already tried to call the method deleteEnemy, and just give it the unused Enemy.
But it isnt possible - when i just do this:
public static void deleteEnemy(Enemy e){
System.out.println("test");
enemys.remove(e);
}
It will be just removed from the list, but coninues existing on the Main JPanel.
And i cannot say
remove(e);
Because then i try to call a non static function in a static.
So, how could i delete an Enemy? Someone knows?
Thanks for help!
The hole code: (Game.java)
And, Enemy.java:
package Game;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class Field extends JPanel implements Runnable{
public static Player player = new Player();
public static ArrayList<Enemy> enemys = new ArrayList<Enemy>();
private Thread moveBackground = new Thread(this);
private boolean bgMoving = false;
public static boolean addMob = false;
private int x = 0;
private int bgSpeed = -1;
public Field(){
setBounds(0, 0, 800, 600);
setFocusable(true);
setLayout(null);
addKeyListener(new Handler());
add(player);
}
public void paintComponent(Graphics g){
Field.super.paintComponent(g);
g.drawImage(Images.images[0], x, 0, this);
}
public static void deleteEnemy(Enemy e){
System.out.println("test");
enemys.remove(e);
}
public void run(){
while(!Player.death){
if(bgMoving){
bgMoving = true;
x += bgSpeed;
if(x < -(Images.images[0].getWidth(this) - this.getWidth() - 20)){
bgMoving = false;
}
repaint();
try { Thread.sleep(20); } catch (InterruptedException e) {}
}
if(addMob){
enemys.add(new Enemy());
add(enemys.get(enemys.size() - 1));
addMob = false;
}
}
JOptionPane.showMessageDialog(null, "DIED!");
}
public class Handler extends KeyAdapter {
public void keyPressed(KeyEvent e) {
player.KeyPressed(e);
if(!bgMoving){
if(Game.running){
bgMoving = true;
if(moveBackground.getState().toString() == "NEW"){
moveBackground.start();
}
}
}
}
public void keyReleased(KeyEvent e) {
player.KeyReleased(e);
}
}
}
And, Enemy.java:
package Game;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Enemy extends JPanel implements Runnable{
Thread t = new Thread(this);
private double x = Game.width();
private double y = Math.random() * Game.height();
private double xF = 0, yF = 0;
private boolean destroyed = false;
public Enemy(){
setBounds((int) x, (int) y, 100, 50);
setOpaque(false);
t.start();
}
public void paintComponent(Graphics g){
Enemy.super.paintComponent(g);
g.setColor(Color.GREEN);
g.drawImage(Images.images[2], 0, 0, this);
}
public void run() {
while(!destroyed){
if(Game.running){
x--;
if(getBounds().intersects(Field.player.getBounding())){
Player.death = true;
}
if(x < 0){
Field.deleteEnemy(this);
}
setBounds((int) x, (int) y, 100, 50);
try{Thread.sleep(10);}catch(InterruptedException e){}
}
}
}
}

After removing you will need to call revalidate() and repaint()

[Too long for a comment]
I think the problem is in your logic on removing an Enemy/JPanel:
You are removing it from the ArrayList only, what about the containing JPanel/JFrame you added it to?
You must remove the JPanel from its container (maybe another JPanel or the JFrame) not just the ArrayList via Component#remove(Component c).
If you drew the Enemy images directly in paintComponent(...) of your container via iterating the ArrayList; removing it from the ArrayList would be sufficient, as it will no longer be in the Array and thus no longer drawn on the next repaint().
+1 to #Optional, you may need to call revalidate() and repaint() on the container for the affects of the removed JPanel/Enemy to be shown.
Also as #darijan mentioned, the use of static variables along with instance is not really a great design (though for certain designs this may be fine).
In your case if you need access to an instance method of another class, within another class, simply pass the instance of the class whos method you would like to access to the object which will access it.
Here is some psuedo code expressing much of the above mentioned problems / solutions:
public class Field extends JPanel {
private ArrayList<Enemy> enemies;
public Field() {
...
enemies.add(new Enemy(this));//create a new enemy and pas it the JPanel instance so it may access instance methods of this class
}
//ONLY USED IF JPanel for Enemy is ommited and Enemy class created which represents Enemy object and not Enemy object and aJPanel
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
ArrayList<Enemy> enemiesClone = new ArrayList<>(enemies);//copy array into another so we don't get a ConcurrentModificaton exception if removeEnemy is called while iterating the list
if(!enemiesClone.isEmpty())
for(Enemy e:enemiesClone) {//iterate through array of images
draw(e.getImage(),e.getX(),e.getY(),this);
}
}
public void removeEnemy(Enemy e) {
enemies.remove(e);//remove from the array
//ONLY USED IF JPanels are used as Enemy
remove(e);//remove from the JPanel
//so the changes of removed panel can be visible seen
revalidate();
repaint();
}
}
class Enemy extends JPanel //extends JPanel should be ommited for paintComponent method of drawing an enemy onscreen
{
private int x,y;
private BufferedImage image;
private Field f;
public Enemy(Field f) {//constructor accepts Field instance to access instance method for the class
this.f=f;
}
public void update() {
if(offscreen||dead) {
f.removeEnemy(this);//call removeEnemy which is an instance method of Field
}
}
//BELOW METHODS ONLY USED WHEN Enemy represents object and not a JPanel which can draw its image itself (and update position by simply changing co-ordinates)
public BufferedImage getImage() {
return image;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
For a more detailed look check Game Development Loop, Logic and Collision detection Java Swing 2D I made which will give you the basics needed for most 2D games. However I do not use JPanels rather draw directly to a container.

Where do you add an Enemy to JPanel?
Basically, you should call remove on Field JPanel:
public void deleteEnemy(Enemy e){
System.out.println("test");
enemys.remove(e);
this.remove(e);
}
The method should not be static.

Java making a ball bounce, its left a trail behind?

Im newish to java, and im writing a pong game.
Ive got the ball to move (Thats my first priority) and make it apear on screen.
But for some Reason its leaving a black line behind it, I dont know if im supposed to errase this or something, but heres the code of my 2 classes (The Ball Class is just a class to save the info of the ball)
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import javax.swing.JFrame;
public class Main extends Canvas implements Runnable{
private static final long serialVersionUID = 1L;
public static int Width=650;
public static int Height=600;
public boolean Running=false;
public Thread thread;
public Ball ball = new Ball();
public static void main(String[] args){
Main game = new Main();
JFrame frame = new JFrame();
frame.setSize(Width+25, Height+49);
frame.setTitle("Pong By Poo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
frame.add(game);
game.start();
}
public void start(){
if(Running==true){
return;
} else {
Running=true;
thread = new Thread(this);
thread.start();
}
}
public void run(){
while(Running==true){
try{
Thread.sleep(5);
Draw();
Update();
ball.YVelocity();
ball.XVelocity();
} catch(Exception e){}
}
}
public void Draw(){
BufferStrategy bs = this.getBufferStrategy();
if(bs==null){
createBufferStrategy(2);
} else {
Graphics g = bs.getDrawGraphics();
g.setColor(Color.BLACK);
g.fillOval(ball.BallLocationX, ball.BallLocationY, 20, 20);
g.dispose();
bs.show();
}
}
public void Update(){
if(ball.BallLocationX==0) {
ball.BallMovementX=true;
System.out.println("Ball has hit the Left");
}
if(ball.BallLocationX==Width) {
ball.BallMovementX=false;
System.out.println("Ball has hit the Right");
}
if(ball.BallLocationY==0){
ball.BallMovementY=true;
System.out.println("Ball has hit the Top");
}
if(ball.BallLocationY==Height){
ball.BallMovementY=false;
System.out.println("Ball has hit the bottom");
}
}
}
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Ball extends JPanel{
public int BallLocationX;
public int BallLocationY;
public boolean BallMovementY; //true makes the ball go up, false makes it go down
public boolean BallMovementX; //True makes the ball go right, false makes it go left.
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(BallLocationX, BallLocationY, 10, 10);
}
//moves the ball left to right
public int YVelocity(){
if(BallMovementY==true){
BallLocationY++;
} else {
BallLocationY--;
}
return BallLocationY;
}
//Moves the ball up and down
public int XVelocity(){
if(BallMovementX==true){
BallLocationX+=2;
} else {
BallLocationX-=2;
}
return BallLocationX;
}
}
Please help!

Essentially, everywhere your ball moves stays permanently Color.BLACK on your Canvas. If you want to get rid of that, you need to refresh every time the ball moves and repaint the Canvas to Color.WHITE (or whatever) before painting the ball's position again.
Specifically, look at your code here:
public void Draw(){
BufferStrategy bs = this.getBufferStrategy();
if(bs==null){
createBufferStrategy(2);
} else {
Graphics g = bs.getDrawGraphics();
g.setColor(Color.BLACK);
g.fillOval(ball.BallLocationX, ball.BallLocationY, 20, 20);
g.dispose();
bs.show();
}
}
There is no logic here that overwrites your previous changes to the Canvas indicating the ball's location.
Also, as a side nitpick, Java standards are to have method names in camelCase.
And to answer the question in the comments: there is nothing in the Canvas API which automatically understands what you want the default background of the Canvas to be and can reset all other graphics attributes to that. To get this functionality, however, all you'll need to do is repaint your default layout (whether it's all one color, or a basic background image, or anything else) before painting the ball's position on top of it.