java语言程序设计 14.2 comparable

public class ComparableCircle extends Circle implements Comparable {public static void main(String[] args) {    // Create two comarable rects    ComparableCircle circle1 = new ComparableCircle(5);    ComparableCircle circle2 = new ComparableCircle(15);    // Display the max rect    ComparableCircle circle3 = (ComparableCircle)Max.max(circle1, circle2);    System.out.println("The max circle's radius is " + circle3.getRadius());    System.out.println(circle3);  }public ComparableCircle(double radius) {    super(radius);  }  /** Implement the compareTo method defined in Comparable */  public int compareTo(Object o) {    if (getRadius() > ((ComparableCircle) o).getRadius())      return 1;    else if (getRadius() < ((ComparableCircle) o).getRadius())      return -1;    else      return 0;  }  static class Max {  /** Return the maximum of two objects */  public static Comparable max (Comparable o1, Comparable o2) {    if (o1.compareTo(o2) > 0)      return o1;    else      return o2;  }}}