Computer Science 210
Data Structures
Fall 2018, Siena College
Circles BlueJ Project
Click here to download a BlueJ project for Circles.
Circles Source Code
The Java source code for Circles is below. Click on a file name to download it.
/**
* Representation of a circle in the plane
*
* @author Jim Teresco and the CSIS 210 class
*/
public class Circle
{
// instance variables
private double centerX;
private double centerY;
private double radius;
// default constructor, circle at the origin of
// radius 1 for lack of a better obvious option
public Circle() {
centerX = 0.0;
centerY = 0.0;
radius = 1.0;
}
// general-purpose constructor
public Circle(double x, double y, double r) {
centerX = x;
centerY = y;
radius = r;
}
// toString for printing
public String toString() {
return "center (" + centerX + "," + centerY + "), radius " +
radius;
}
// compute our circumference
public double circumference() {
return 2 * radius * Math.PI;
}
// compute the area
public double area() {
return Math.PI * radius * radius;
}
// trivial getters and setters
public void setCenterX(double cx) {
centerX = cx;
}
public void setCenterY(double cy) {
centerY = cy;
}
public void setRadius(double r) {
radius = r;
}
// alternate mutators
public void setDiameter(double d) {
radius = d / 2.0;
}
// set both coordinates of the center
public void setCenter(double x, double y) {
centerX = x;
centerY = y;
}
// translate the circle by dx, dy
public void moveBy(double dx, double dy) {
centerX += dx;
centerY += dy;
}
// scale the circle in place
public void scale(double s) {
radius *= s;
}
// a method to call to print out lots of information about our circle
public void printInfo() {
System.out.println(this);
System.out.println("Circumference: " + circumference() + ", area: " + area());
}
// a main method to try out a lot of these
public static void main(String args[]) {
Circle def = new Circle();
System.out.println("Default circle: " + def);
System.out.println("its circumference: " + def.circumference());
Circle c1 = new Circle(2, 4, 5);
System.out.println("c1: " + c1);
System.out.println("its circumference: " + c1.circumference());
Circle c2 = new Circle(3.5, 9.0, 3.0);
System.out.println("c2 on construction:");
c2.printInfo();
c2.setDiameter(0.25);
System.out.println("After setDiameter(0.25)");
c2.printInfo();
c2.setCenter(0, 100);
System.out.println("After setCenter(0, 100)");
c2.printInfo();
c2.scale(1000);
System.out.println("After scale(1000)");
c2.printInfo();
c2.moveBy(-34.2, 982.1);
System.out.println("After moveBy(-34.2, 982.1)");
c2.printInfo();
}
}