I really need help, my 1st assigment is due tomorrow and i've been working on it for a really long time and is just not getting it!!!!
So please help me, it will be greatly appreciated.
These are the questions that I haven't been able to figure out.
Add a new method called shuffleHorizontal that takes a single integer as its argument. When invoked, the method causes the circle to do a slow shuffle to the right by the specified number of pixels, then back to the left, leaving the circle exactly where it started. (That's assuming the input is positive — if the input is negative, the circle will shuffle left, then right.) Add a comment describing your new method. Hint: If your solution is more than a few lines long, you've made this more difficult than it needs to be!
Optional: Modify the code so that circles are visible (on the screen) when they're first created. (No extra points for this one, but completing it will produce a profound sense of well being.)
And here is the code
import java.awt.*;
import java.awt.geom.*;
/**
* A circle that can be manipulated and that draws itself on a canvas.
*
* @author Michael Kolling and David J. Barnes and Tiana Orta
* @version 2008.03.30
*/
public class Circle
{
private int diameter;
private int xPosition;
private int yPosition;
private String color;
private boolean isVisible;
/**
* Create a new circle at default position with default color.
*/
public Circle()
{
diameter = 30;
xPosition = 20;
yPosition = 60;
color = "yellow";
isVisible = false;
}
/**
* Make this circle visible. If it was already visible, do nothing.
*/
public void makeVisible()
{
isVisible = true;
draw();
}
/**
* Make this circle invisible. If it was already invisible, do nothing.
*/
public void makeInvisible()
{
erase();
isVisible = false;
}
/**
* Move the circle a few pixels to the right.
*/
public void moveRight()
{
moveHorizontal(30);
}
/**
* Move the circle a few pixels to the left.
*/
public void moveLeft()
{
moveHorizontal(-30);
}
/**
* Move the circle a few pixels up.
*/
public void moveUp()
{
moveVertical(-30);
}
/**
* Move the circle a few pixels down.
*/
public void moveDown()
{
moveVertical(30);
}
/**
* Move the circle a few pixels up and right (NorthEast).
*/
public void moveNorthEast()
{
moveVertical(-30); moveHorizontal(30);
}
/**
* Move the circle horizontally by 'distance' pixels.
*/
public void moveHorizontal(int distance)
{
erase();
xPosition += distance;
draw();
}
/**
* Move the circle vertically by 'distance' pixels.
*/
public void moveVertical(int distance)
{
erase();
yPosition += distance;
draw();
}
/**
* Slowly move the circle horizontally by 'distance' pixels.
*/
public void slowMoveHorizontal(int distance)
{
int delta;
if(distance < 0)
{
delta = -1;
distance = -distance;
}
else
{
delta = 1;
}
for(int i = 0; i < distance; i++)
{
xPosition += delta;
draw();
}
}
/**
* Slowly move the circle vertically by 'distance' pixels.
*/
public void slowMoveVertical(int distance)
{
int delta;
if(distance < 0)
{
delta = -1;
distance = -distance;
}
else
{
delta = 1;
}
for(int i = 0; i < distance; i++)
{
yPosition += delta;
draw();
}
}
/**
* Slowly move the circle vertically by 'distance' pixels.
*/
public void shuffleHorizontal(int distance)
{
int delta;
if(distance < 0)
{
delta = -1;
distance = -distance;
}
{
delta = 1;
}
for(int i = 0; i < distance; i++)
{
xPosition += delta;
draw();
erase();
xPosition += -delta;
draw();
}
}
/**
* Change the size to the new size (in pixels). Size must be >= 0.
*/
public void changeSize(int newDiameter)
{
erase();
diameter = newDiameter;
draw();
}
/**
* Change the color. Valid colors are "red", "yellow", "blue", "green",
* "magenta" and "black".
*/
public void changeColor(String newColor)
{
color = newColor;
draw();
}
/**
* Draw the circle with current specifications on screen.
*/
private void draw()
{
if(isVisible) {
Canvas canvas = Canvas.getCanvas();
canvas.draw(this, color, new Ellipse2D.Double(xPosition, yPosition,
diameter, diameter));
canvas.wait(10);
}
}
/**
* Erase the circle on screen.
*/
private void erase()
{
if(isVisible) {
Canvas canvas = Canvas.getCanvas();
canvas.erase(this);
}
}
}