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8
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/BallDemo.ctxt Executable file
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#BlueJ class context
comment0.params=
comment0.target=BallDemo()
comment0.text=\n\ Create\ a\ BallDemo\ object.\ Creates\ a\ fresh\ canvas\ and\ makes\ it\ visible.\n
comment1.params=
comment1.target=void\ bounce()
comment1.text=\n\ Simulate\ two\ bouncing\ balls\n
numComments=2

54
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/BallDemo.java Executable file
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import java.awt.Color;
/**
* Class BallDemo - a short demonstration showing animation with the
* Canvas class.
*
* @author Michael Kölling and David J. Barnes
* @version 2016.02.29
*/
public class BallDemo
{
private Canvas myCanvas;
/**
* Create a BallDemo object. Creates a fresh canvas and makes it visible.
*/
public BallDemo()
{
myCanvas = new Canvas("Ball Demo", 600, 500);
}
/**
* Simulate two bouncing balls
*/
public void bounce()
{
int ground = 400; // position of the ground line
myCanvas.setVisible(true);
// draw the ground
myCanvas.setForegroundColor(Color.BLACK);
myCanvas.drawLine(50, ground, 550, ground);
// create and show the balls
BouncingBall ball = new BouncingBall(50, 50, 16, Color.BLUE, ground, myCanvas);
ball.draw();
BouncingBall ball2 = new BouncingBall(70, 80, 20, Color.RED, ground, myCanvas);
ball2.draw();
// make them bounce
boolean finished = false;
while (!finished) {
myCanvas.wait(50); // small delay
ball.move();
ball2.move();
// stop once ball has travelled a certain distance on x axis
if(ball.getXPosition() >= 550 || ball2.getXPosition() >= 550) {
finished = true;
}
}
}
}

20
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/BouncingBall.ctxt Executable file
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#BlueJ class context
comment0.params=xPos\ yPos\ ballDiameter\ ballColor\ groundPos\ drawingCanvas
comment0.target=BouncingBall(int,\ int,\ int,\ java.awt.Color,\ int,\ Canvas)
comment0.text=\n\ Constructor\ for\ objects\ of\ class\ BouncingBall\n\n\ @param\ xPos\ \ the\ horizontal\ coordinate\ of\ the\ ball\n\ @param\ yPos\ \ the\ vertical\ coordinate\ of\ the\ ball\n\ @param\ ballDiameter\ \ the\ diameter\ (in\ pixels)\ of\ the\ ball\n\ @param\ ballColor\ \ the\ color\ of\ the\ ball\n\ @param\ groundPos\ \ the\ position\ of\ the\ ground\ (where\ the\ wall\ will\ bounce)\n\ @param\ drawingCanvas\ \ the\ canvas\ to\ draw\ this\ ball\ on\n
comment1.params=
comment1.target=void\ draw()
comment1.text=\n\ Draw\ this\ ball\ at\ its\ current\ position\ onto\ the\ canvas.\n
comment2.params=
comment2.target=void\ erase()
comment2.text=\n\ Erase\ this\ ball\ at\ its\ current\ position.\n
comment3.params=
comment3.target=void\ move()
comment3.text=\n\ Move\ this\ ball\ according\ to\ its\ position\ and\ speed\ and\ redraw.\n
comment4.params=
comment4.target=int\ getXPosition()
comment4.text=\n\ return\ the\ horizontal\ position\ of\ this\ ball\n
comment5.params=
comment5.target=int\ getYPosition()
comment5.text=\n\ return\ the\ vertical\ position\ of\ this\ ball\n
numComments=6

109
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/BouncingBall.java Executable file
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import java.awt.*;
import java.awt.geom.*;
/**
* Class BouncingBall - a graphical ball that observes the effect of gravity. The ball
* has the ability to move. Details of movement are determined by the ball itself. It
* will fall downwards, accelerating with time due to the effect of gravity, and bounce
* upward again when hitting the ground.
*
* This movement can be initiated by repeated calls to the "move" method.
*
* @author Michael Kölling (mik)
* @author David J. Barnes
* @author Bruce Quig
*
* @version 2016.02.29
*/
public class BouncingBall
{
private static final int GRAVITY = 3; // effect of gravity
private int ballDegradation = 2;
private Ellipse2D.Double circle;
private Color color;
private int diameter;
private int xPosition;
private int yPosition;
private final int groundPosition; // y position of ground
private Canvas canvas;
private int ySpeed = 1; // initial downward speed
/**
* Constructor for objects of class BouncingBall
*
* @param xPos the horizontal coordinate of the ball
* @param yPos the vertical coordinate of the ball
* @param ballDiameter the diameter (in pixels) of the ball
* @param ballColor the color of the ball
* @param groundPos the position of the ground (where the wall will bounce)
* @param drawingCanvas the canvas to draw this ball on
*/
public BouncingBall(int xPos, int yPos, int ballDiameter, Color ballColor,
int groundPos, Canvas drawingCanvas)
{
xPosition = xPos;
yPosition = yPos;
color = ballColor;
diameter = ballDiameter;
groundPosition = groundPos;
canvas = drawingCanvas;
}
/**
* Draw this ball at its current position onto the canvas.
**/
public void draw()
{
canvas.setForegroundColor(color);
canvas.fillCircle(xPosition, yPosition, diameter);
}
/**
* Erase this ball at its current position.
**/
public void erase()
{
canvas.eraseCircle(xPosition, yPosition, diameter);
}
/**
* Move this ball according to its position and speed and redraw.
**/
public void move()
{
// remove from canvas at the current position
erase();
// compute new position
ySpeed += GRAVITY;
yPosition += ySpeed;
xPosition +=2;
// check if it has hit the ground
if (yPosition >= (groundPosition - diameter) && ySpeed > 0) {
yPosition = (int)(groundPosition - diameter);
ySpeed = -ySpeed + ballDegradation;
}
// draw again at new position
draw();
}
/**
* return the horizontal position of this ball
*/
public int getXPosition()
{
return xPosition;
}
/**
* return the vertical position of this ball
*/
public int getYPosition()
{
return yPosition;
}
}

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Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/Canvas.ctxt Executable file
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#BlueJ class context
comment0.params=title
comment0.target=Canvas(java.lang.String)
comment0.text=\n\ Create\ a\ Canvas\ with\ default\ height,\ width\ and\ background\ color\ \n\ (300,\ 300,\ white).\n\ @param\ title\ \ title\ to\ appear\ in\ Canvas\ Frame\ \ \ \ \ \n
comment1.params=title\ width\ height
comment1.target=Canvas(java.lang.String,\ int,\ int)
comment1.text=\n\ Create\ a\ Canvas\ with\ default\ background\ color\ (white).\n\ @param\ title\ \ title\ to\ appear\ in\ Canvas\ Frame\n\ @param\ width\ \ the\ desired\ width\ for\ the\ canvas\n\ @param\ height\ \ the\ desired\ height\ for\ the\ canvas\n
comment10.params=xPos\ yPos\ diameter
comment10.target=void\ eraseCircle(int,\ int,\ int)
comment10.text=\n\ Erase\ the\ internal\ dimensions\ of\ the\ given\ circle.\ This\ is\ a\ \n\ convenience\ method.\ A\ similar\ effect\ can\ be\ achieved\ with\n\ the\ "erase"\ method.\n
comment11.params=xPos\ yPos\ width\ height
comment11.target=void\ eraseRectangle(int,\ int,\ int,\ int)
comment11.text=\n\ Erase\ the\ internal\ dimensions\ of\ the\ given\ rectangle.\ This\ is\ a\ \n\ convenience\ method.\ A\ similar\ effect\ can\ be\ achieved\ with\n\ the\ "erase"\ method.\n
comment12.params=shape
comment12.target=void\ erase(java.awt.Shape)
comment12.text=\n\ Erase\ a\ given\ shape's\ interior\ on\ the\ screen.\n\ @param\ \ shape\ \ the\ shape\ object\ to\ be\ erased\ \n
comment13.params=shape
comment13.target=void\ eraseOutline(java.awt.Shape)
comment13.text=\n\ Erases\ a\ given\ shape's\ outline\ on\ the\ screen.\n\ @param\ \ shape\ \ the\ shape\ object\ to\ be\ erased\ \n
comment14.params=image\ x\ y
comment14.target=boolean\ drawImage(java.awt.Image,\ int,\ int)
comment14.text=\n\ Draws\ an\ image\ onto\ the\ canvas.\n\ @param\ \ image\ \ \ the\ Image\ object\ to\ be\ displayed\ \n\ @param\ \ x\ \ \ \ \ \ \ x\ co-ordinate\ for\ Image\ placement\ \n\ @param\ \ y\ \ \ \ \ \ \ y\ co-ordinate\ for\ Image\ placement\ \n\ @return\ \ returns\ boolean\ value\ representing\ whether\ the\ image\ was\ \n\ \ \ \ \ \ \ \ \ \ completely\ loaded\ \n
comment15.params=text\ x\ y
comment15.target=void\ drawString(java.lang.String,\ int,\ int)
comment15.text=\n\ Draws\ a\ String\ on\ the\ Canvas.\n\ @param\ \ text\ \ \ the\ String\ to\ be\ displayed\ \n\ @param\ \ x\ \ \ \ \ \ x\ co-ordinate\ for\ text\ placement\ \n\ @param\ \ y\ \ \ \ \ \ y\ co-ordinate\ for\ text\ placement\n
comment16.params=text\ x\ y
comment16.target=void\ eraseString(java.lang.String,\ int,\ int)
comment16.text=\n\ Erases\ a\ String\ on\ the\ Canvas.\n\ @param\ \ text\ \ \ \ \ the\ String\ to\ be\ displayed\ \n\ @param\ \ x\ \ \ \ \ \ \ \ x\ co-ordinate\ for\ text\ placement\ \n\ @param\ \ y\ \ \ \ \ \ \ \ y\ co-ordinate\ for\ text\ placement\n
comment17.params=x1\ y1\ x2\ y2
comment17.target=void\ drawLine(int,\ int,\ int,\ int)
comment17.text=\n\ Draws\ a\ line\ on\ the\ Canvas.\n\ @param\ \ x1\ \ \ x\ co-ordinate\ of\ start\ of\ line\ \n\ @param\ \ y1\ \ \ y\ co-ordinate\ of\ start\ of\ line\ \n\ @param\ \ x2\ \ \ x\ co-ordinate\ of\ end\ of\ line\ \n\ @param\ \ y2\ \ \ y\ co-ordinate\ of\ end\ of\ line\ \n
comment18.params=newColor
comment18.target=void\ setForegroundColor(java.awt.Color)
comment18.text=\n\ Sets\ the\ foreground\ color\ of\ the\ Canvas.\n\ @param\ \ newColor\ \ \ the\ new\ color\ for\ the\ foreground\ of\ the\ Canvas\ \n
comment19.params=
comment19.target=java.awt.Color\ getForegroundColor()
comment19.text=\n\ Returns\ the\ current\ color\ of\ the\ foreground.\n\ @return\ \ \ the\ color\ of\ the\ foreground\ of\ the\ Canvas\ \n
comment2.params=title\ width\ height\ bgColor
comment2.target=Canvas(java.lang.String,\ int,\ int,\ java.awt.Color)
comment2.text=\n\ Create\ a\ Canvas.\n\ @param\ title\ \ title\ to\ appear\ in\ Canvas\ Frame\n\ @param\ width\ \ the\ desired\ width\ for\ the\ canvas\n\ @param\ height\ \ the\ desired\ height\ for\ the\ canvas\n\ @param\ bgClour\ \ the\ desired\ background\ color\ of\ the\ canvas\n
comment20.params=newColor
comment20.target=void\ setBackgroundColor(java.awt.Color)
comment20.text=\n\ Sets\ the\ background\ color\ of\ the\ Canvas.\n\ @param\ \ newColor\ \ \ the\ new\ color\ for\ the\ background\ of\ the\ Canvas\ \n
comment21.params=
comment21.target=java.awt.Color\ getBackgroundColor()
comment21.text=\n\ Returns\ the\ current\ color\ of\ the\ background\n\ @return\ \ \ the\ color\ of\ the\ background\ of\ the\ Canvas\ \n
comment22.params=newFont
comment22.target=void\ setFont(java.awt.Font)
comment22.text=\n\ changes\ the\ current\ Font\ used\ on\ the\ Canvas\n\ @param\ \ newFont\ \ \ new\ font\ to\ be\ used\ for\ String\ output\n
comment23.params=
comment23.target=java.awt.Font\ getFont()
comment23.text=\n\ Returns\ the\ current\ font\ of\ the\ canvas.\n\ @return\ \ \ \ \ the\ font\ currently\ in\ use\n
comment24.params=width\ height
comment24.target=void\ setSize(int,\ int)
comment24.text=\n\ Sets\ the\ size\ of\ the\ canvas.\n\ @param\ \ width\ \ \ \ new\ width\ \n\ @param\ \ height\ \ \ new\ height\ \n
comment25.params=
comment25.target=java.awt.Dimension\ getSize()
comment25.text=\n\ Returns\ the\ size\ of\ the\ canvas.\n\ @return\ \ \ \ \ The\ current\ dimension\ of\ the\ canvas\n
comment26.params=milliseconds
comment26.target=void\ wait(int)
comment26.text=\n\ Waits\ for\ a\ specified\ number\ of\ milliseconds\ before\ finishing.\n\ This\ provides\ an\ easy\ way\ to\ specify\ a\ small\ delay\ which\ can\ be\n\ used\ when\ producing\ animations.\n\ @param\ \ milliseconds\ \ the\ number\ \n
comment3.params=visible
comment3.target=void\ setVisible(boolean)
comment3.text=\n\ Set\ the\ canvas\ visibility\ and\ brings\ canvas\ to\ the\ front\ of\ screen\n\ when\ made\ visible.\ This\ method\ can\ also\ be\ used\ to\ bring\ an\ already\n\ visible\ canvas\ to\ the\ front\ of\ other\ windows.\n\ @param\ visible\ \ boolean\ value\ representing\ the\ desired\ visibility\ of\n\ the\ canvas\ (true\ or\ false)\ \n
comment4.params=
comment4.target=boolean\ isVisible()
comment4.text=\n\ Provide\ information\ on\ visibility\ of\ the\ Canvas.\n\ @return\ \ true\ if\ canvas\ is\ visible,\ false\ otherwise\n
comment5.params=shape
comment5.target=void\ draw(java.awt.Shape)
comment5.text=\n\ Draw\ the\ outline\ of\ a\ given\ shape\ onto\ the\ canvas.\n\ @param\ \ shape\ \ the\ shape\ object\ to\ be\ drawn\ on\ the\ canvas\n
comment6.params=shape
comment6.target=void\ fill(java.awt.Shape)
comment6.text=\n\ Fill\ the\ internal\ dimensions\ of\ a\ given\ shape\ with\ the\ current\ \n\ foreground\ color\ of\ the\ canvas.\n\ @param\ \ shape\ \ the\ shape\ object\ to\ be\ filled\ \n
comment7.params=xPos\ yPos\ diameter
comment7.target=void\ fillCircle(int,\ int,\ int)
comment7.text=\n\ Fill\ the\ internal\ dimensions\ of\ the\ given\ circle\ with\ the\ current\ \n\ foreground\ color\ of\ the\ canvas.\n\ @param\ \ xPos\ \ The\ x-coordinate\ of\ the\ circle\ center\ point\n\ @param\ \ yPos\ \ The\ y-coordinate\ of\ the\ circle\ center\ point\n\ @param\ \ diameter\ \ The\ diameter\ of\ the\ circle\ to\ be\ drawn\n
comment8.params=xPos\ yPos\ width\ height
comment8.target=void\ fillRectangle(int,\ int,\ int,\ int)
comment8.text=\n\ Fill\ the\ internal\ dimensions\ of\ the\ given\ rectangle\ with\ the\ current\ \n\ foreground\ color\ of\ the\ canvas.\ This\ is\ a\ convenience\ method.\ A\ similar\ \n\ effect\ can\ be\ achieved\ with\ the\ "fill"\ method.\n
comment9.params=
comment9.target=void\ erase()
comment9.text=\n\ Erase\ the\ whole\ canvas.\n
numComments=27

364
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/Canvas.java Executable file
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import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
/**
* Class Canvas - a class to allow for simple graphical
* drawing on a canvas.
*
* @author Michael Kölling (mik)
* @author Bruce Quig
*
* @version 2016.02.29
*/
public class Canvas
{
private JFrame frame;
private CanvasPane canvas;
private Graphics2D graphic;
private Color backgroundColor;
private Image canvasImage;
/**
* Create a Canvas with default height, width and background color
* (300, 300, white).
* @param title title to appear in Canvas Frame
*/
public Canvas(String title)
{
this(title, 300, 300, Color.white);
}
/**
* Create a Canvas with default background color (white).
* @param title title to appear in Canvas Frame
* @param width the desired width for the canvas
* @param height the desired height for the canvas
*/
public Canvas(String title, int width, int height)
{
this(title, width, height, Color.white);
}
/**
* Create a Canvas.
* @param title title to appear in Canvas Frame
* @param width the desired width for the canvas
* @param height the desired height for the canvas
* @param bgClour the desired background color of the canvas
*/
public Canvas(String title, int width, int height, Color bgColor)
{
frame = new JFrame();
canvas = new CanvasPane();
frame.setContentPane(canvas);
frame.setTitle(title);
canvas.setPreferredSize(new Dimension(width, height));
backgroundColor = bgColor;
frame.pack();
setVisible(true);
}
/**
* Set the canvas visibility and brings canvas to the front of screen
* when made visible. This method can also be used to bring an already
* visible canvas to the front of other windows.
* @param visible boolean value representing the desired visibility of
* the canvas (true or false)
*/
public void setVisible(boolean visible)
{
if(graphic == null) {
// first time: instantiate the offscreen image and fill it with
// the background color
Dimension size = canvas.getSize();
canvasImage = canvas.createImage(size.width, size.height);
graphic = (Graphics2D)canvasImage.getGraphics();
graphic.setColor(backgroundColor);
graphic.fillRect(0, 0, size.width, size.height);
graphic.setColor(Color.black);
}
frame.setVisible(true);
}
/**
* Provide information on visibility of the Canvas.
* @return true if canvas is visible, false otherwise
*/
public boolean isVisible()
{
return frame.isVisible();
}
/**
* Draw the outline of a given shape onto the canvas.
* @param shape the shape object to be drawn on the canvas
*/
public void draw(Shape shape)
{
graphic.draw(shape);
canvas.repaint();
}
/**
* Fill the internal dimensions of a given shape with the current
* foreground color of the canvas.
* @param shape the shape object to be filled
*/
public void fill(Shape shape)
{
graphic.fill(shape);
canvas.repaint();
}
/**
* Fill the internal dimensions of the given circle with the current
* foreground color of the canvas.
* @param xPos The x-coordinate of the circle center point
* @param yPos The y-coordinate of the circle center point
* @param diameter The diameter of the circle to be drawn
*/
public void fillCircle(int xPos, int yPos, int diameter)
{
Ellipse2D.Double circle = new Ellipse2D.Double(xPos, yPos, diameter, diameter);
fill(circle);
}
/**
* Fill the internal dimensions of the given rectangle with the current
* foreground color of the canvas. This is a convenience method. A similar
* effect can be achieved with the "fill" method.
*/
public void fillRectangle(int xPos, int yPos, int width, int height)
{
fill(new Rectangle(xPos, yPos, width, height));
}
/**
* Erase the whole canvas.
*/
public void erase()
{
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
Dimension size = canvas.getSize();
graphic.fill(new Rectangle(0, 0, size.width, size.height));
graphic.setColor(original);
canvas.repaint();
}
/**
* Erase the internal dimensions of the given circle. This is a
* convenience method. A similar effect can be achieved with
* the "erase" method.
*/
public void eraseCircle(int xPos, int yPos, int diameter)
{
Ellipse2D.Double circle = new Ellipse2D.Double(xPos, yPos, diameter, diameter);
erase(circle);
}
/**
* Erase the internal dimensions of the given rectangle. This is a
* convenience method. A similar effect can be achieved with
* the "erase" method.
*/
public void eraseRectangle(int xPos, int yPos, int width, int height)
{
erase(new Rectangle(xPos, yPos, width, height));
}
/**
* Erase a given shape's interior on the screen.
* @param shape the shape object to be erased
*/
public void erase(Shape shape)
{
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.fill(shape); // erase by filling background color
graphic.setColor(original);
canvas.repaint();
}
/**
* Erases a given shape's outline on the screen.
* @param shape the shape object to be erased
*/
public void eraseOutline(Shape shape)
{
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.draw(shape); // erase by drawing background color
graphic.setColor(original);
canvas.repaint();
}
/**
* Draws an image onto the canvas.
* @param image the Image object to be displayed
* @param x x co-ordinate for Image placement
* @param y y co-ordinate for Image placement
* @return returns boolean value representing whether the image was
* completely loaded
*/
public boolean drawImage(Image image, int x, int y)
{
boolean result = graphic.drawImage(image, x, y, null);
canvas.repaint();
return result;
}
/**
* Draws a String on the Canvas.
* @param text the String to be displayed
* @param x x co-ordinate for text placement
* @param y y co-ordinate for text placement
*/
public void drawString(String text, int x, int y)
{
graphic.drawString(text, x, y);
canvas.repaint();
}
/**
* Erases a String on the Canvas.
* @param text the String to be displayed
* @param x x co-ordinate for text placement
* @param y y co-ordinate for text placement
*/
public void eraseString(String text, int x, int y)
{
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.drawString(text, x, y);
graphic.setColor(original);
canvas.repaint();
}
/**
* Draws a line on the Canvas.
* @param x1 x co-ordinate of start of line
* @param y1 y co-ordinate of start of line
* @param x2 x co-ordinate of end of line
* @param y2 y co-ordinate of end of line
*/
public void drawLine(int x1, int y1, int x2, int y2)
{
graphic.drawLine(x1, y1, x2, y2);
canvas.repaint();
}
/**
* Sets the foreground color of the Canvas.
* @param newColor the new color for the foreground of the Canvas
*/
public void setForegroundColor(Color newColor)
{
graphic.setColor(newColor);
}
/**
* Returns the current color of the foreground.
* @return the color of the foreground of the Canvas
*/
public Color getForegroundColor()
{
return graphic.getColor();
}
/**
* Sets the background color of the Canvas.
* @param newColor the new color for the background of the Canvas
*/
public void setBackgroundColor(Color newColor)
{
backgroundColor = newColor;
graphic.setBackground(newColor);
}
/**
* Returns the current color of the background
* @return the color of the background of the Canvas
*/
public Color getBackgroundColor()
{
return backgroundColor;
}
/**
* changes the current Font used on the Canvas
* @param newFont new font to be used for String output
*/
public void setFont(Font newFont)
{
graphic.setFont(newFont);
}
/**
* Returns the current font of the canvas.
* @return the font currently in use
**/
public Font getFont()
{
return graphic.getFont();
}
/**
* Sets the size of the canvas.
* @param width new width
* @param height new height
*/
public void setSize(int width, int height)
{
canvas.setPreferredSize(new Dimension(width, height));
Image oldImage = canvasImage;
canvasImage = canvas.createImage(width, height);
graphic = (Graphics2D)canvasImage.getGraphics();
graphic.setColor(backgroundColor);
graphic.fillRect(0, 0, width, height);
graphic.drawImage(oldImage, 0, 0, null);
frame.pack();
}
/**
* Returns the size of the canvas.
* @return The current dimension of the canvas
*/
public Dimension getSize()
{
return canvas.getSize();
}
/**
* Waits for a specified number of milliseconds before finishing.
* This provides an easy way to specify a small delay which can be
* used when producing animations.
* @param milliseconds the number
*/
public void wait(int milliseconds)
{
try
{
Thread.sleep(milliseconds);
}
catch (InterruptedException e)
{
// ignoring exception at the moment
}
}
/************************************************************************
* Inner class CanvasPane - the actual canvas component contained in the
* Canvas frame. This is essentially a JPanel with added capability to
* refresh the image drawn on it.
*/
private class CanvasPane extends JPanel
{
public void paint(Graphics g)
{
g.drawImage(canvasImage, 0, 0, null);
}
}
}

19
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/README.TXT Executable file
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Bouncing Balls - a demonstration of graphical output on a Canvas class.
This project is part of the material for the book
Objects First with Java - A Practical Introduction using BlueJ
Sixth edition
David J. Barnes and Michael Kölling
Pearson Education, 2016
This project is discussed in chapter 6.
This project provides a short graphical demo in the BallDemo class.
This project provides scope for extension. The Canvas class does not
usually need to be changed. It may be best to treat it as a library
class (open the editor and switch to "documentation" view).
Other classes can be changed or added. The book contains suggestions
for various exercises.

64
Semester 1/Programming 1/Java/examples/projects/chapter06/bouncing-balls/package.bluej Executable file
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#BlueJ package file
dependency1.from=BallDemo
dependency1.to=Canvas
dependency1.type=UsesDependency
dependency2.from=BouncingBall
dependency2.to=Canvas
dependency2.type=UsesDependency
dependency3.from=BallDemo
dependency3.to=BouncingBall
dependency3.type=UsesDependency
objectbench.height=76
objectbench.width=724
package.editor.height=394
package.editor.width=616
package.editor.x=70
package.editor.y=80
package.numDependencies=3
package.numTargets=3
package.showExtends=true
package.showUses=true
project.charset=UTF-8
readme.editor.height=707
readme.editor.width=917
readme.editor.x=65
readme.editor.y=79
target1.editor.height=714
target1.editor.width=1075
target1.editor.x=53
target1.editor.y=42
target1.height=60
target1.name=BallDemo
target1.naviview.expanded=true
target1.showInterface=false
target1.type=ClassTarget
target1.typeParameters=
target1.width=110
target1.x=110
target1.y=50
target2.editor.height=776
target2.editor.width=931
target2.editor.x=78
target2.editor.y=23
target2.height=60
target2.name=BouncingBall
target2.naviview.expanded=true
target2.showInterface=false
target2.type=ClassTarget
target2.typeParameters=
target2.width=110
target2.x=260
target2.y=140
target3.editor.height=756
target3.editor.width=948
target3.editor.x=53
target3.editor.y=51
target3.height=60
target3.name=Canvas
target3.naviview.expanded=true
target3.showInterface=false
target3.type=ClassTarget
target3.typeParameters=
target3.width=100
target3.x=400
target3.y=230