数据结构与算法chapter-0

/** 
   An interface for methods that return
   the perimeter and area of an object.

   @author Frank M. Carrano
   @version 4.0
*/
public interface Measurable
{
   /** Gets the perimeter.
       @return  The perimeter. */
   public double getPerimeter();
   
   /** Gets the area.
       @return  The area. */
   public double getArea();
} // end Measurable

/**
   An interface for a class of names.
   
   @author Frank M. Carrano
   @version 4.0
*/
public interface NameInterface
{
  public void setName(String firstName, String lastName);
  public String getName();

  public void setFirst(String firstName);
  public String getFirst();

  public void setLast(String lastName);
  public String getLast();

  public void giveLastNameTo(NameInterface aName);

  public String toString();
} // end NameInterface

/**
   A class that represents a circle.
   
   @author Frank M. Carrano
   @version 4.0
*/
public class Circle implements Circular
{
	private double radius;

	public void setRadius(double newRadius)
	{
		radius = newRadius;
	} // end setRadius

	public double getRadius()
	{
		return radius;
	} // end getRadius

	public double getArea()
	{
		return Math.PI * radius * radius;
	} // end getArea
} // end Circle

/**
   An interface for objects that have a radius.
   
   @author Frank M. Carrano
   @version 4.0
*/
public interface Circular
{
	public void setRadius(double newRadius);
	public double getRadius();
} // end Circular

/**
   @author Frank M. Carrano
   @version 4.0
*/
public interface Callable extends Nameable
{
   public void come(String petName);
} // end Callable

/**
   @author Frank M. Carrano
   @version 4.0
*/
public interface Capable
{
	public void hear();
	public void respond();
} // end Capable

/**
   @author Frank M. Carrano
   @version 4.0
*/
public interface Trainable extends Callable, Capable
{
	public void sit();
	public void speak();
	public void lieDown();
} // end Trainable

/**
   An interface of public constants.
   @author Frank M. Carrano
   @version 4.0
*/
public interface ConstantsInterface
{
   public static final double INCHES_PER_CENTIMETER = 0.39370079;
   public static final double FEET_PER_METER = 3.2808399;
   public static final double MILES_PER_KILOMETER = 0.62137119;
} // end ConstantsInterface

/**
   @author Frank M. Carrano
   @version 4.0
*/
public class Demo implements ConstantsInterface
{
   public static void main(String[] args)
   {
      System.out.println(FEET_PER_METER);
      System.out.println(ConstantsInterface.MILES_PER_KILOMETER);
   } // end main
} // end Demo