import java.util.*;
//shows the importance of overriding equals and hashCode methods
class Circle {
private int xPos, yPos, radius;
// other methods elided
public Circle(int x, int y, int r) {
xPos = x;
yPos = y;
radius = r;
}
@Override
public boolean equals(Object arg) {
if (arg == null) return false;
if (this == arg) return true;
if (arg instanceof Circle) {
Circle that = (Circle) arg;
if ((this.xPos == that.xPos) && (this.yPos == that.yPos) && (this.radius == that.radius)) {
return true;
}
}
return false;
}
// @Override
// public int hashCode() {
// // use bit-manipulation operators such as ^ to generate close to unique
// // hash codes here we are using the magic numbers 7, 11 and 53,
// // but you can use any numbers, preferably primes
// return (7 * xPos) ^ (11 * yPos) ^ (53 * yPos);
// }
}
class Main {
public static void main(String[] args) {
Circle newCircle = new Circle(10, 20, 5);
Set<Object> circleList = new HashSet<Object>();
circleList.add((Object) newCircle);
System.out.println(circleList.contains(new Circle(10, 20, 5)));
}
}
