Code: Java Sphere class
import javax.swing.*;
import java.awt.*;
import java.awt.geom.Ellipse2D;
public class Sphere extends JPanel {
private boolean flashinglights = false;
private int x = 168;
private int y = 75;
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
if (flashinglights) { //This is the flash option. Here it should change between grey and orange
g2.setColor(Color.ORANGE);
Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
g2.draw(ball);
g2.fill(ball);
} else {
g2.setColor(Color.gray); //This should stay grey as it does now.
Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
g2.draw(ball);
g2.fill(ball);
}
}
public void chooseflashinglights(){ //Ignore these methods
flashinglights = false;
}
public void choosesteady(){
flashinglights = true;
}
public void flickerorange(int d) { y = y + d; }
public void flickergrey(int d) { y = y + d; }
public static void main(String[] args) {
JFrame scFrame = new AnimationViewer();
scFrame.setTitle("Circle");
scFrame.setSize(400, 400);
scFrame.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));
scFrame.setVisible(true);
}
}
Animation Viewer Class:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class AnimationViewer extends JFrame {
JButton jbtFlash = new JButton("Flash");
JButton jbtSteady = new JButton("Steady");
JPanel bPanel = new JPanel();
Sphere sphPanel = new Sphere();
Timer timer;
public AnimationViewer() {
this.add(bPanel, BorderLayout.SOUTH);
bPanel.add(jbtFlash);
bPanel.setLayout(new GridLayout(1,2));
bPanel.add(jbtSteady);
this.add(sphPanel, BorderLayout.CENTER);
jbtSteady.addActionListener(new SteadyLights());
jbtFlash.addActionListener(new FlashingLights());
timer = new Timer(100, new TimerListener());
timer.start();
}
class TimerListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
sphPanel.flickerorange(0);
sphPanel.flickergrey(0);
repaint();
}
}
class FlashingLights implements ActionListener{
public void actionPerformed(ActionEvent e){
sphPanel.chooseflashinglights();
}
}
class SteadyLights implements ActionListener{
public void actionPerformed(ActionEvent e){
sphPanel.choosesteady();
}
}
}
So right now there is a sphere that appears on the screen. There are two buttons showed below. Flash and Steady. On the steady button it has to stay one colour (orange) which it does not.
Now on Flash it has to change from Orange to grey every 100 milli seconds.
I know it has to be something to do with Action listeners but how exactly do I implement this?
You have a lot of extra code. I would do it like this. Write flashing logic in paintComponent method. Then create just one timer. On tick call the paintComponent method for every 100ms. On flash button click start the timer, on steady button click stop the timer and call paintComponent once.
Sphere class:
public class Sphere extends JPanel {
private boolean flashinglights = false;
private int x = 168;
private int y = 75;
private Color[] colors = new Color[] {Color.ORANGE, Color.GRAY };
private int colorIndex = 0;
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
if (!flashinglights) {
g2.setColor(Color.ORANGE);
Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
g2.draw(ball);
g2.fill(ball);
} else {
if(colorIndex > colors.length - 1)
colorIndex = 0;
g2.setColor(colors[colorIndex++]);
Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
g2.draw(ball);
g2.fill(ball);
}
}
public void chooseflashinglights(){ //Ignore these methods
flashinglights = true;
}
public void choosesteady(){
flashinglights = false;
}
public static void main(String[] args) {
JFrame scFrame = new AnimationViewer();
scFrame.setTitle("Circle");
scFrame.setSize(400, 400);
scFrame.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));
scFrame.setVisible(true);
}
}
AnimationViewer class:
public class AnimationViewer extends JFrame {
JButton jbtFlash = new JButton("Flash");
JButton jbtSteady = new JButton("Steady");
JPanel bPanel = new JPanel();
Sphere sphPanel = new Sphere();
Timer timer;
public AnimationViewer() {
this.add(bPanel, BorderLayout.SOUTH);
bPanel.add(jbtFlash);
bPanel.setLayout(new GridLayout(1,2));
bPanel.add(jbtSteady);
this.add(sphPanel, BorderLayout.CENTER);
timer = new Timer(100, new TimerListener());
jbtSteady.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
sphPanel.choosesteady();
timer.stop();
sphPanel.repaint();
}
});
jbtFlash.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
sphPanel.chooseflashinglights();
timer.start();
}
});
}
class TimerListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
sphPanel.repaint();
}
}
}
I would do things a bit differently.
I'd have a field in my drawing JPanel class that indicates what color should be shown.
For instance, if there are only two colors that are swapped, I'd use a boolean field, and would swap it's value in my timer, and then base the color draw on its value.
The paintComponent method would use that field, the boolean, to decide which Color to use for g.setColor(...).
If many colors are drawn, the field could be a combination of an array of Color together with an int index into the array. Then I'd increment the index as needed, and use the index in paintComponent to decide which color to draw with.
I'd change that field in my Timer's ActionListener -- just a single call to change it, not your strange call to flicker orange and flicker gray.
I'd start the Timer with one button
I'd stop it with the other button. That's all the button's action listener would do, simply start or stop the timer.
Related
I've written some code that essentially animates a sequence of images and adds them to a frame when I run the file.
I want to implement a functionality where I can add this animation to two different areas of a JPanel that has a BorderLayout (North and West).
I want to do this using a button but I don't know how to do that. I am new to event handling and layout managers.
How do I go about this?
My code for the animation:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ImageSequence extends JPanel implements ActionListener {
private ImageSQPanel imageSQPanel;
private static int frameNumber = -1;
private Timer timer;
private void buildUI(Container container, Image[] arrows) {
int fps = 10;
int delay = 1000 / fps;
timer = new Timer(delay, this);
timer.setInitialDelay(0);
timer.setCoalesce(true);
imageSQPanel = new ImageSQPanel(arrows);
container.add(imageSQPanel, BorderLayout.CENTER);
}
private synchronized void startAnimation() {
if (!timer.isRunning()) {
timer.start();
}
}
public void actionPerformed(ActionEvent e) {
frameNumber++;
imageSQPanel.repaint();
}
class ImageSQPanel extends JPanel {
Image arrowAnimation[];
ImageSQPanel(Image[] arrowAnimation) {
this.arrowAnimation = arrowAnimation;
}
//Draw the current frame of animation.
public void paintComponent(Graphics g) {
super.paintComponent(g); //paint background
//Paint the frame into the image.
try {
g.drawImage(arrowAnimation[ImageSequence.frameNumber % 10], 0, 0, this);
} catch (ArrayIndexOutOfBoundsException e) {
//On rare occasions, this method can be called
//when frameNumber is still -1. Do nothing.
}
}
}
//Invoked only when this is run as an application.
public static void main(String[] args) {
Image[] waving = new Image[7];
for (int i = 1; i <= 7; i++) {
waving[i - 1] = Toolkit.getDefaultToolkit().getImage(
"/Users/sarthaksachdeva/Documents/IntelliJ Projects/Animation/src/images/Arrow" + i + ".png");
}
JFrame f = new JFrame("ImageSequenceTimer");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
ImageSequence controller = new ImageSequence();
controller.buildUI(f.getContentPane(), waving);
controller.startAnimation();
f.setSize(new Dimension(200, 200));
f.setVisible(true);
}
}
So I want to set my Rectangle's color to whatever the JColorChooser picks, but unfortunately, I don't think that it recognises it as it just stays black, unless I assign it a real color like Color.BLUE.
This is the rectangle which should get the color from the other class:
TestProjectJPanel jpp = new TestProjectJPanel();
public void paintComponent(Graphics g){
super.paintComponent(g);
Rectangle r = new Rectangle(500,300,250,400);
g.setColor(jpp.bodyColour);
g.fillRect((int)r.getX(),(int)r.getY(),(int)r.getHeight(),(int)r.getWidth());
g.setColor(Color.BLUE);
g.drawString("banana", 50, 60);
}
and this is the class which has the color itself
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TestProjectJPanel extends JFrame {
public JButton b;
public JButton u;
public JButton l;
public JButton r;
public String s;
public Color color = (Color.WHITE);
public JPanel panel;
public Color bodyColour;
public Color doorColour;
public Color wheelColour;
public TestProjectJPanel(){
JFrame f = new JFrame();
panel = new JPanel();
panel.setBackground(color);
// bodyColour button
b = new JButton("Body Colour");
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
bodyColour = JColorChooser.showDialog(null, "Pick the colour", bodyColour);
if (bodyColour == null)
bodyColour = Color.RED;
}
});
u = new JButton("Wheel Colour");
u.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent event){
wheelColour = JColorChooser.showDialog(null, "Pick the colour", wheelColour);
if (wheelColour == null)
wheelColour = (Color.BLACK);
}
});
l = new JButton("Door Colour");
l.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
doorColour = JColorChooser.showDialog(null, "Pick the colour", doorColour);
if(doorColour==null)
doorColour = (Color.RED);
}
});
r = new JButton("Change Name");
r.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
s = JOptionPane.showInputDialog("What name do you want to change it to?");
}
});
}
}
This is the whole code, which the Rectangle is included in.
import javax.swing.*;
import java.util.*;
import java.awt.*;
public class TestProjectDialog extends JPanel {
TestProjectJPanel jpp = new TestProjectJPanel();
public void paintComponent(Graphics g) {
super.paintComponent(g);
Rectangle r = new Rectangle(500, 300, 250, 400);
g.setColor(jpp.bodyColour);
g.fillRect((int) r.getX(), (int) r.getY(), (int) r.getHeight(), (int) r.getWidth());
g.setColor(Color.BLUE);
g.drawString("banana", 50, 60);
}
public static void main(String[] args){
TestProjectJPanel jpp = new TestProjectJPanel();
/* JOptionPane.showMessageDialog(null, "Just about to draw a REALLY GOOD 2D car \n just need input please.");
jpp.s = JOptionPane.showInputDialog("Imagine a car, what is it's name?");
if(jpp.s == null || (jpp.s != null && ("".equals(jpp.s))))
{
JOptionPane.showMessageDialog(null, "Invalid input/pressed cancel, closing program.");
System.exit(0);
}
JOptionPane.showMessageDialog(null, "Ah okay, so it's name is " + jpp.s); */
JFrame f = new JFrame("My 2D Car Drawing");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jpp.setBackground(Color.WHITE);
f.setSize(1440,900);
f.add(new TestProjectDialog(), BorderLayout.CENTER);
f.add(jpp.b, SpringLayout.SOUTH); // bodyColour
// f.add(jpp.u, SpringLayout. NORTH); // wheelColour
// f.add(jpp.l, SpringLayout.WEST); // doorColour
// f.add(jpp.r, SpringLayout.EAST); // changeName
f.setVisible(true);
}
}
Could anyone help me and give me a solution for why it's not recognising the color?
Without a runnable example that demonstrates your problem, it is impossible to 100% sure, but from the sounds of it, you have created two more instances of TestProjectJPanel and/or paint panel, so what you think you're drawing to isn't actually on the screen.
However, it also sounds like you're not adhering to basic OO design, ensuring that the object is self managed, but instead, allowing the object to ascertain it's state from the properties of another object.
Instead, your paint/rectangle pane should be self contained, that is, all the properties it needs should be managed by it (this could also include a model, but that's going beyond the problem at hand).
For example, the ControlPane manages the interactions between the user (choosing a color) and the setting of that color on the PaintPane, which deals only with painting the results...
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class ColorTest {
public static void main(String[] args) {
new ColorTest();
}
public ColorTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
PaintPane paintPane = new PaintPane();
ControlPane controlPane = new ControlPane(paintPane);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(paintPane);
frame.add(controlPane, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ControlPane extends JPanel {
public ControlPane(PaintPane paintPane) {
JButton colorButton = new JButton("Color");
add(colorButton);
colorButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Color color = JColorChooser.showDialog(ControlPane.this, "Background", paintPane.getFillColor());
if (color != null)
paintPane.setFillColor(color);
}
});
}
}
public class PaintPane extends JPanel {
private Color fillColor = Color.RED;
public PaintPane() {}
public Color getFillColor() {
return fillColor;
}
public void setFillColor(Color fillColor) {
this.fillColor = fillColor;
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(fillColor);
g2d.fillRect(50, 50, 100, 100);
g2d.dispose();
}
}
}
I have an assignment that calls for a ball to move around the screen based on which button the user clicks and for the ball to alternate between red and green with the click of another button. It all works but the color change. I have a listener and class reacting to the button click but I dont seem to get a change. Is there a better / simpler way to accomplish this?
Thanks in advance for the help!
Code I have:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Lab2b extends JFrame {
Lab2b(){
setTitle("Lab 2");
Lab2Panel p = new Lab2Panel();
add(p);
}
public static void main(String[] args){
Lab2b frame = new Lab2b();
frame.setTitle("Lab 2 - Ball Mover ");
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600, 400);
frame.setVisible(true);
}
}
class Lab2Panel extends JPanel{
Lab2Button canvas = new Lab2Button();
JPanel panel = new JPanel();
Lab2Panel () {
setLayout(new BorderLayout());
JButton leftButton = new JButton("left");
JButton rightButton = new JButton("right");
JButton upButton = new JButton("up");
JButton downButton = new JButton("down");
JButton colorButton = new JButton("Change Color");
panel.add(leftButton);
panel.add(rightButton);
panel.add(upButton);
panel.add(downButton);
panel.add(colorButton);
this.add(canvas, BorderLayout.CENTER);
this.add(panel, BorderLayout.SOUTH);
leftButton.addActionListener(new LeftListener(canvas));
rightButton.addActionListener(new RightListener(canvas));
upButton.addActionListener(new UpListener(canvas));
downButton.addActionListener(new DownListener(canvas));
colorButton.addActionListener(new ColorChangeListener(canvas));
}
}
class Lab2Button extends JPanel {
int radius = 5;
int x = -1;
int y = -1;
protected void paintComponent(Graphics g){
if (x<0 || y<0) {
x = getWidth() / 2 - radius;
y = getHeight() / 2 - radius;
}
super.paintComponent(g);
g.setColor(Color.RED);
g.drawOval(x,y, 2 * radius, 2 * radius);
}
public void moveLeft(){
x -= 5;
this.repaint();
}
public void moveRight(){
x += 5;
this.repaint();
}
public void moveUp(){
y -= 5;
this.repaint();
}
public void moveDown(){
y += 5;
this.repaint();
}
public void colorChange(){
this.repaint();
}
}
class LeftListener implements ActionListener{
private Lab2Button canvas;
LeftListener(Lab2Button canvas) {
this.canvas = canvas;
}
public void actionPerformed(ActionEvent e){
canvas.moveLeft();
}
}
class RightListener implements ActionListener{
private Lab2Button canvas;
RightListener(Lab2Button canvas) {
this.canvas = canvas;
}
public void actionPerformed(ActionEvent e){
canvas.moveRight();
}
}
class UpListener implements ActionListener{
private Lab2Button canvas;
UpListener(Lab2Button canvas) {
this.canvas = canvas;
}
public void actionPerformed(ActionEvent e){
canvas.moveUp();
}
}
class DownListener implements ActionListener{
private Lab2Button canvas;
DownListener(Lab2Button canvas) {
this.canvas = canvas;
}
public void actionPerformed(ActionEvent e){
canvas.moveDown();
}
}
class ColorChangeListener implements ActionListener {
private Lab2Button canvas;
ColorChangeListener(Lab2Button canvas) {
this.canvas = canvas;
}
public void actionPerformed(ActionEvent e){
canvas.colorChange();
}
}
Button Movement Listener Class Code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Lab2MoveBallListener extends Lab2Button implements ActionListener {
public void actionPerformed(ActionEvent e){
this.moveLeft();
}
}
Okay, changed this code:
public void colorChange(){
this.repaint();
}
To this and it errors on compile with: error: cannot find symbol
if (g.getColor() = Color.RED){
public void colorChange(){
if (g.getColor() = Color.RED){
g.setColor(Color.GREEN);
}
else{
g.setColor(Color.RED);
}
this.repaint();
}
Have a look at using a JColorChooser. It can set the ball color as required. See How to Use Color Choosers
Here you have hard coded the color making it impossible to modify the ball color. Use a class member Color variable and assign it from getColor.
Aside: Remember to set the color before calling drawOval:
g.setColor(ballColor);
g.drawOval(x, y, 2 * radius, 2 * radius);
When you call your method colorChange() you never say to change a color, you just repaint the screen. You need to change the color somewhere. To do this I'd have a color variable and in if statement within your ActionPerformed method for the Color Button. The if would have boolean that if it's true, set the color variable equal to this color, else set it equal to the other color. Now instead of g.setColor(Color.RED); in your paintComponent(), you'd have g.setColor(colorVariable);. Hope this helps and solves your problem.
I have my code set up to where the Boolean boxDetect will be set to true if the mouse is clicked within the Rectangle startButton. The rest is just formatting nothing special! This is the initial screen before you press inside the rectangle, and once inside the rectangle and pressed it should repaint the screen to a rectangle at points 400,400.
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.*;
public class spaceInvadersIntroScreen implements MouseListener
{
private JFrame frame;
private MyPanel panel;
private double startButtonX = 0;
private double startButtonY = 0;
private Rectangle startButton;
private Boolean boxDetect = false;
public static void main(String[] args){ new spaceInvadersIntroScreen(); }
public spaceInvadersIntroScreen()
{
frame = new JFrame("Space Invaders");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
startButtonX = screenSize.getWidth() / 2; //Finds the X value of the center of the screen
startButtonY = screenSize.getHeight() / 2; //Finds the Y value of the center of the screen
frame.setSize(screenSize); //width and height
panel = new MyPanel();
frame.getContentPane().add(panel);
frame.setVisible(true);
startButton = new Rectangle((int)(startButtonX - 200), (int)(startButtonY - 75), 400, 150); //Creates Rectangle in the middle of the screen
}
class MyPanel extends JPanel
{
private static final long serialVersionUID = 1L;
public void paint(Graphics g)
{
if(boxDetect == false)
{
Graphics2D g2d = (Graphics2D) g;
//Background
g2d.setColor(Color.BLACK);
g2d.fillRect(0,0, 1440, 870);
//Code for an X centered title regardless of the screen length
String title = "SPACE INVADERS";
Font textFont = new Font("monospaced", Font.BOLD, 150);
FontMetrics textMetrics = g2d.getFontMetrics(textFont);
g2d.setFont(textFont);
int centeredX = (this.getWidth()/2) - (textMetrics.stringWidth(title)/2);
//Prints SPACE INVADERS to the screen
g2d.setColor(Color.WHITE);
g2d.setFont(textFont);
g2d.drawString(title, centeredX, 200);
//draw the Button
g2d.setColor(Color.white);
g2d.fill(startButton);
}
else
{
g.setColor(Color.black);
g.drawRect(400, 400, 400, 400);
}
}
}
#Override
public void mouseReleased(MouseEvent e)
{
double xCoord = e.getX();
double yCoord = e.getY();
if(startButton.contains(xCoord,yCoord) == true)
{
boxDetect = true;
}
panel.repaint();
}
#Override
public void mouseClicked(MouseEvent e) {}
#Override
public void mousePressed(MouseEvent e) {}
#Override
public void mouseEntered(MouseEvent e) {}
#Override
public void mouseExited(MouseEvent e) {}
}
You need to add the MouseListener for it to work. Question: Where do you call addMouseListener(...)? Answer: you don't. Solution: make this method call to add the MouseListener to the component that needs it.
I have the following program which has some very strange and unwanted behavior when it runs. Its supposed to have two buttons, "Start" and "Stop, but when I click "Start" another button shows up right below "Start". Here's a print screen of what I'm talking about:
What am I doing wrong and how do I fix this ugly problem?
Here's the code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Random;
public class TwoButtonsTest {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
TwoButtonsTest test = new TwoButtonsTest();
test.go();
}
public void go() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
final DrawPanel myDraw = new DrawPanel();
frame.getContentPane().add(BorderLayout.CENTER, myDraw);
frame.getContentPane().add(BorderLayout.NORTH, startButton);
frame.getContentPane().add(BorderLayout.SOUTH, stopButton);
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
if(!isClicked) {
}
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
int red = (int)(Math.random()*256);
int blue = (int)(Math.random()*256);
int green = (int)(Math.random()*256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth()-wd);
int y = rand.nextInt(getHeight()-ht);
g.fillRect(x,y,wd,ht);
}
} // close inner class
}
Also I'm trying to get the Start button to do two things. One is to of course start the animation but when the Stop button is pressed and I press Start again, I want it to clean the screen so to speak and start the animation again a new. Any tips on that?
You do not call super.paintComponent(Graphics g) in overriden paintComponent(..) method which you should in order to honor the paint chain and thus the painting of other components.
This call should also be the first call within the method:
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
//do painting here
}
A probem might arise that drawings are not persistent. You must than have a way to store drawings and redraw every time. The most common is an ArrayList which will hold objects to be drawn (thus you cann add to the list remove etc), you would than iterate over the list and redraw each object in paintComponent. See my answer here for an example.
Also please remember to create and manipulate Swing components on Event Dispatch Thread :
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//create UI and components here
}
});
Dont call setSize(..) on JFrame rather override getPreferredSize() of JPanel and return an appropriate height which fits all components, than call JFrame#pack() before setting JFrame visible (but after adding all components).
No need for getContentPane().add(..) as of Java 6+ add(..) defaults to contentPane
Do not re declare Random i.e Random r=new Random() each time paintComponent is called as this will make the distributions of the values less random rather initiate it once when class is created and call methods on the instance
Here is the fixed code (with above fixes implemented):
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.*;
public class TwoButtonsTest {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
TwoButtonsTest test = new TwoButtonsTest();
test.go();
}
});
}
final DrawPanel myDraw = new DrawPanel();
public void go() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
frame.add(myDraw, BorderLayout.CENTER);
frame.add(startButton, BorderLayout.NORTH);
frame.add(stopButton, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
//needs to be implemented
if (!isClicked) {
}
myDraw.clearRects();
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
private ArrayList<MyRectangle> rects = new ArrayList<>();
private Random rand = new Random();
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
addRect();
for (MyRectangle r : rects) {
g.setColor(r.getColor());
g.fillRect(r.x, r.y, r.width, r.height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
public void clearRects() {
rects.clear();
}
public void addRect() {
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
rects.add(new MyRectangle(x, y, wd, ht, new Color(red, blue, green)));
}
} // close inner class
}
class MyRectangle extends Rectangle {
Color color;
public MyRectangle(int x, int y, int w, int h, Color c) {
super(x, y, w, h);
this.color = c;
}
public Color getColor() {
return color;
}
}
I wish I could offer a solution, but as of yet I haven't found one. I can tell you the root of the "problem" here lies in the way you are drawing the Center section of your BorderLayout. You are overriding the whole paintComponent() function for this program and having whatever it creates put into the Center of your BoarderLayout. In this case, each time you click a button, the program calls the repaint to draw the image of a clicked button, but since you have also added ANY of the drawn objects to the Center panel, it also is drawn there. Since this specific repaint doesn't specify a location, it goes in the upper left corner.
I fixed your button problem on my Windows XP computer by invoking SwingUtilities.
I formatted your Java code.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class TwoButtonsTest implements Runnable {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
SwingUtilities.invokeLater(new TwoButtonsTest());
}
#Override
public void run() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
final DrawPanel myDraw = new DrawPanel();
frame.getContentPane().add(BorderLayout.CENTER, myDraw);
frame.getContentPane().add(BorderLayout.NORTH, startButton);
frame.getContentPane().add(BorderLayout.SOUTH, stopButton);
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// needs to be implemented
if (!isClicked) {
}
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
#Override
public void paintComponent(Graphics g) {
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
g.fillRect(x, y, wd, ht);
}
} // close inner class
}
To clean the screen when you press the Start button, you're going to have to add some methods to your DrawPanel class.
Here's one way to do it.
class DrawPanel extends JPanel {
protected boolean eraseCanvas;
public void setEraseCanvas(boolean eraseCanvas) {
this.eraseCanvas = eraseCanvas;
}
#Override
public void paintComponent(Graphics g) {
if (eraseCanvas) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
} else {
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
g.fillRect(x, y, wd, ht);
}
}
} // close inner class