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Timer of swing not performing as expected

I was suggested not to use sleep for pausing purpose and instead use swing timer but still its not working.The animation i want to achieve is a ball travelling from the top left corner diagonally towards the bottom.
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
class Show_starter {
int x, y;
JFrame window = new JFrame("Graphic_show");
Graphic_panel jp = new Graphic_panel();
public static void main(String[] args) {
Show_starter start = new Show_starter();
start.go();
}
private void go() {
window.getContentPane().add(BorderLayout.CENTER, jp);
window.setSize(600,800);
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
class Graphic_panel extends JPanel {
public void paintComponent(Graphics g) {
for ( int i = 0; i < 100; ++i) {
g.setColor(Color.white);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
x++;
y++;
try {
Timer tmr = new Timer(1000, new TimerListener()); //This fires an event after every 1 sec after it has started by start().
//But The ball travels too much fast and stops at a point and again travels very fast.
tmr.serRepeats(false); // even this is not working.
tmr.start();
//should i use repaint here or in Listener for this timer?
} catch (Exception e){}
}
}
class TimerListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
jp.repaint();
}
}
}
}
The behaviour it is showing is very odd ball first goes at very high speed and stops momentarily at a point and again moves at same speed.
I have also tried to change the time for timer event to fire but the same thing happens.
Even inside loop where I have started timer the follow function call is not working
setRepeats(false);

don't create new timers always one timer is enough .decrees timing interval bit more .1 second is too slow for a animation.you don't need a loop and don't increment x and y inside paintcomponet() method because this method get called for some reason for example when you resize,minimize,maximize.
the unexpected behavior is due to your loop and creating new timers(). for example in x y start at zero but in first second x y increased to 100,100 in next paint you see them in a 100,100 position .that's look like quick move and then stop ...
example code (edited)
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class Show_starter {
private Timer tmr;
int x, y;
JFrame window = new JFrame("Graphic_show");
Graphic_panel jp = new Graphic_panel();
public static void main(String[] args) {
Show_starter start = new Show_starter();
start.go();
}
private void go() {
window.getContentPane().add(BorderLayout.CENTER, jp);
window.setSize(600, 800);
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
tmr = new Timer(10, new ActionListener() { // time gap in millisecond
#Override
public void actionPerformed(ActionEvent ae) {
jp.increse();
jp.repaint();
}
});
tmr.start();
}
class Graphic_panel extends JPanel {
public void increse() {
x++;
y++;
if (x > 100) { // stop animation at x>100
tmr.stop();
}
}
public void paintComponent(Graphics g) {
g.setColor(Color.white);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
}
}
}
output (smoother than that)

Firstly you should not use a loop inside paint component.
public void paintComponent(Graphics g){
g.setColor(Color.white);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
}
Just draw it and make x and y public in the class so that you can easily access from outside
Now run a runnable (consult invokelater and swingUtilities) or create a new Thread
inside public void run() do whatever animations you want to do . You can use a loop but add Thread.sleep(//in miliseconds) and repaint() in each iteration .
note : you need to change the x and y and repaint() so that it is drawn in a new position. And the sleep() is needed to slow down the execution otherwise it can't be visible to viewer.

Java, redraw scrolling background image at the same point the last image ends

My problem is that i have an image which is X in length, and i want to make it so that the image continually scrolls in the background of my game.
In order to do this, and it no be obvious to the player the next background image has to be redrawn at the point at which the previous image ends, this is what i cannot figure out.
Currently i can have continuous redrawing of the image, but just as the old image ends the new image is drawn back at (0,0) so it is obvious that the background is being redrawn.
I know what the problem is, but the solution is avoiding me. The problem is that when i redrawn the image, i reset location to 0. I can't figure out another way to do this currently so maybe someone could help me in someway.
Just a side note the JPanel is 1000 in width.
Here is the code so far:
package cje.chris.edwards.game;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class Board extends JPanel implements ActionListener{
Player player;
Image background;
Timer timer;
private int scrollSpeed, location;
public Board(){
player = new Player();
this.addKeyListener(new Listener());
setFocusable(true);
ImageIcon img_ic = new ImageIcon("map.png");
background= img_ic.getImage();
location = 0;
//5 milliseconds
scrollSpeed = -2;
timer = new Timer(5, this);
timer.start();
}
#Override
public void actionPerformed(ActionEvent e) {
//called using timer.start() and its delay
repaint();
}
public void paint(Graphics g){
super.paint(g);
Graphics2D graphics_2d = (Graphics2D) g;
//This is the section where my problem lies.
if(location != 0 && Math.abs(location) % (background.getWidth(null) - 1000) == 0){
graphics_2d.drawImage(background, 1000, 0, null);
location = 0;
}
graphics_2d.drawImage(background, location += scrollSpeed, 0, null);
graphics_2d.drawImage(player.getImage(), 50, 100, null);
System.out.println(location);
}
private class Listener extends KeyAdapter{
public void keyPressed(KeyEvent e){
scrollSpeed = -1;
player.move(e);
}
}
}
Is there a way i can reset location to the end of the last image? so it looks completely seamless. Thanks again!
This is the image i am using, just in case anybody wants to try my code:
https://warosu.org/data/ic/img/0015/95/1385339455019.png

try this
public void paint(Graphics g){
super.paint(g);
Graphics2D graphics_2d = (Graphics2D) g;
// define bounds by width of image
while (location > background.getWidth(null)){
location -= background.getWidth(null);
}
while (location < -background.getWidth(null)){
location += background.getWidth(null);
}
// draw image twice to handle any overlap
graphics_2d.drawImage(background, location += scrollSpeed, 0, null);
graphics_2d.drawImage(background, location + background.getWidth(null), 0, null);
System.out.println(location);
}

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.

Graphics2D not clearing transparent image

I have the following snippet of code which should increment a counter on a transparent background on the first monitor. When the image shows 0 it renders fine, but after that (as soon as 1 is hit) the window redraws with an opaque background.
Silly example in practice I know, just broken a real use case down to a simpler piece of code.
It seems the key might be in the paintComponent method of TestCanvas:
g.setColor(new Color(0, 0, 0, 0));
g.clearRect(0, 0, getWidth(), getHeight());
From what I can work out, those two lines should set the drawing colour to completely transparent, then clear the given area with that colour - but this doesn't seem to be holding for beyond the first repaint.
EDIT: Using fillRect instead of clearRect doesn't work because it just paints the transparent rectangle on top of the existing image, so it never gets cleared. 1 is overlayed on 0, then 2 overlayed on 1, etc.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingUtilities;
public class LyricWindow extends JWindow {
private final TestCanvas canvas;
public LyricWindow(Rectangle area, boolean stageView) {
setBackground(new Color(0, 0, 0, 0));
setArea(area);
canvas = new TestCanvas();
canvas.setPreferredSize(new Dimension((int) (area.getMaxX() - area.getMinX()), (int) (area.getMaxY() - area.getMinY())));
add(canvas);
new Thread() {
public void run() {
for(int i = 0; true; i++) {
final int ii = i;
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
canvas.setText(Integer.toString(ii));
}
});
try {
Thread.currentThread().sleep(200);
}
catch(InterruptedException ex) {}
System.out.println(ii);
}
}
}.start();
}
public final void setArea(final Rectangle area) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
if(canvas != null) {
canvas.setPreferredSize(new Dimension((int) (area.getMaxX() - area.getMinX()), (int) (area.getMaxY() - area.getMinY())));
}
setSize((int) (area.getMaxX() - area.getMinX()), (int) (area.getMaxY() - area.getMinY()));
setLocation((int) area.getMinX(), (int) area.getMinY());
}
});
}
public static void main(String[] args) {
LyricWindow w = new LyricWindow(GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices()[0].getConfigurations()[0].getBounds(), false);
w.setVisible(true);
}
}
class TestCanvas extends JPanel {
private String text;
#Override
public void paintComponent(Graphics g) {
g.setColor(new Color(0, 0, 0, 0));
g.clearRect(0, 0, getWidth(), getHeight());
g.setColor(Color.RED);
g.drawString(text, 100, 100);
}
public void setText(String s) {
text = s;
repaint();
}
}

Turned out I had to set the correct composite value before painting. Adding
((Graphics2D)g).setComposite(AlphaComposite.getInstance(AlphaComposite.SRC));
to the start of the paintComponent() method, then using fillRect(), did the trick!

Try g.fillRect(...) instead of g.clearRect(...). I think I ran into a similar problem once, and this may have solved it for me.
I found my original solution to the problem for use with BufferedImages. Not sure why the color White might work while Black would not, but give it a try:
g.setBackground(new Color(255, 255, 255, 0));
g.clearRect(0, 0, width, height);
From the Color class's Javadoc:
An alpha value of 1.0 or 255 means that the color is completely opaque
and an alpha value of 0 or 0.0 means that the color is completely
transparent.

I know this is a bit old, however why don't you just use the JPanel's already built functionality to clear the canvas for you by calling the function in the super class?
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(new Color(0, 0, 0, 0));
g.clearRect(0, 0, getWidth(), getHeight());
g.setColor(Color.RED);
g.drawString(text, 100, 100);
}
That should leave you with a completely blank graphics object to draw on.

If your color is completely transparent, does the clearing actually do anything?
Try setting the alpha value to 255, instead of 0. Problem is, that will "clear" the rectangle to black (0, 0, 0), but I'm not sure it's possible to "clear" it to transparent with clearRect. You might try fillRect instead.

How to get rid of the flicker that appears during my animation?

I'm learning Java by making a small game in a JApplet.
I got a little problem with my sprite's animation.
Here is the code :
this.sprite.setBounds(0,0,20,17);
this.sprite.setIcon(this.rangerDown);
for(int i = 0; i< 16;i++)
{
this.sprite.setBounds(this.sprite.getX(), this.sprite.getY()+1, 20, 17);
this.sprite.update(this.sprite.getGraphics());
try{
Thread.currentThread().sleep(100);
}catch(InterruptedException e){
}
}
It left some flicker during the animation. Once the animation end, the flicker disappears, but it's kind of ugly... I guess there is some step I missed.
I use this method because it gives the better result for now, but I would like to stay without AWT if possible, using Swing instead.
Any ideas how to get rid of the flicker?
Thanks for reading.
Screenshoot (Can't post images, sorry).

This is not a shadow. Its the border of your sprite. It just happens to be black and appears as a shadow. If you change the amount you shift your sprite (lets say by 50 pixels, not just 1) you will see what i mean.
To fix it what you need to do is to draw the background as well each time you update the location of your sprite. Although this will probably produce flickering.
The correct way to do it is to change the way you draw your objects. You need to override the paintComponent method of your panel and then simply call repaint each time you have updated the locations of your sprites.
EDIT:
See this code sample for basic usage. NOTE: This is NOT how you should write animation using Threads. I wrote that to show you what goes in the paintComponent method and wrote the animation Thread to show you that the "shadow" you mentioned is gone. NEVER have a non ending run loop in a thread :)
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) {
JFrame f = new JFrame("Test");
MyPanel c = new MyPanel();
f.getContentPane().add(c);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(350, 100);
f.setVisible(true);
}
}
class MyPanel extends JPanel {
int x = 0;
boolean toTheRight = true;
public MyPanel() {
new Thread(new Runnable() {
#Override
public void run() {
while (true) {
x = (toTheRight)?x+5:x-5;
if (x>300)
toTheRight = false;
if (x<0)
toTheRight = true;
repaint();
try {
Thread.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D)g.create();
g2.setPaint(Color.white);
g2.fillRect(0, 0, getWidth(), getHeight());
g2.setPaint(Color.red);
g2.fillOval(x-2, 50, 4, 4);
}
}

The problem is double buffering.
In Applets:
Double buffering is done almost automatically. Call repaint() instead of paint in your method.
In Swing, there are many ways to do it. I usually go for the BufferStrategy route. When you're initializing your frame, do this:
JFrame frame;
... code to init frame here
frame.createBufferStrategy(2);
Then in your draw methods:
Graphics g = getBufferStrategy().getDrawGraphics();
..code to do drawing here...
g.dispose();
getBufferStrategy().show();