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From: byhesed <byhesed@gmail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Programming question determining two circle's relation
Date: Sat, 30 Apr 2011 01:59:22 -0700 (PDT)
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On Apr 30, 5:33=A0pm, byhesed <byhe...@gmail.com> wrote:
> What's wrong with contains and overlaps method in Circle2D class?
> It returns incorrect answers.
>
> - A method contains(double x, double y) returns true if the specified
> point(x,y) is inside this circle.
> - A method contains(Circle2D circle) returns true if the specified
> circle is inside this circle.
> - A method overlaps(Circle2D circle) return true if the specified
> circle overlaps with this circle.
>
> I calculate the distance between two circles:
> - double distance =3D Math.sqrt(Math.pow(circle.x - getX(), 2.0) +
> Math.pow(circle.y - getY(), 2.0));
>
> It's wired too me because I think it is not wrong.
>
> // TEST CODE
> public class Exercise10_11 {
> =A0 =A0 =A0 =A0 public static void main(String[] args) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Circle2D c1 =3D new Circle2D(2, 2, 5.5);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println("Area is " + c1.getAre=
a());
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println("Perimeter is " + c1.g=
etPerimeter());
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println(c1.contains(3, 3));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println(c1.contains(new Circle=
2D(4, 5, 10.5)));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println(c1.overlaps(new Circle=
2D(3, 5, 2.3)));
> =A0 =A0 =A0 =A0 }
>
> }
>
> // Circle2D Class
> public class Circle2D {
> =A0 =A0 =A0 =A0 private double x;
> =A0 =A0 =A0 =A0 private double y;
> =A0 =A0 =A0 =A0 private double radius;
>
> =A0 =A0 =A0 =A0 public Circle2D() {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 x =3D 0;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 y =3D 0;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 radius =3D 1;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public Circle2D(double x, double y, double radius) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 this.x =3D x;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 this.y =3D y;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 this.radius =3D radius;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public double getX() {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return x;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public double getY() {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return y;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public double getArea() {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return radius * radius * Math.PI;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public double getPerimeter() {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return 2 * radius * Math.PI;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public boolean contains(double x, double y) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 double distance =3D Math.pow(getX() - x, =
2.0) + Math.pow(getY() - y,
> 2.0);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (distance <=3D radius)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return true;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false;
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public boolean contains(Circle2D circle) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 double distance =3D Math.sqrt(Math.pow(ci=
rcle.x - getX(), 2.0) +
> Math.pow(circle.y - getY(), 2.0));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (distance <=3D Math.abs(radius - circl=
e.radius))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return true;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false;
>
> =A0 =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0 public boolean overlaps(Circle2D circle) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 double distance =3D Math.sqrt(Math.pow(ci=
rcle.x - getX(), 2.0) +
> Math.pow(circle.y - getY(), 2.0));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (distance > Math.abs(radius - circle.r=
adius) && distance <
> Math.abs(radius + circle.radius))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return true;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false;
> =A0 =A0 =A0 =A0 }
>
>
>
>
>
>
>
> }

Sorry, I found answers. Formulas were wrong. :)