测试Shape，Rectangle，Circle和ShapeUtil类

abstract class Shape {

  private String name;

  /**
  nowjava - 时  代  Java 提供 
  **/

  public Shape() {

    this.name = "Unknown shape";

  }


  public Shape(String name) {

    this.name = name;

  }


  public String getName() {

    return this.name;

  }


  public void setName(String name) {

    this.name = name;

  }


  // Abstract methods
  /** 
   来自 n o w j a v a . c o m - 时代Java**/

  public abstract void draw();


  public abstract double getArea();


  public abstract double getPerimeter();

}


class Rectangle extends Shape {

  private double width;

  private double height;


  public Rectangle(double width, double height) {

    // Set the shape name as "Rectangle"

    super("Rectangle");

    this.width = width;

    this.height = height;

  }


  // Provide an implementation for inherited abstract draw() method

  public void draw() {

    System.out.println("Drawing a rectangle...");

  }


  // Provide an implementation for inherited abstract getArea() method

  public double getArea() {

    return width * height;

  }


  // Provide an implementation for inherited abstract getPerimeter() method

  public double getPerimeter() {

    return 2.0 * (width + height);

  }

}


class Circle extends Shape {

  private double radius;


  public Circle(double radius) {

    super("Circle");

    this.radius = radius;

  }


  // Provide an implementation for inherited abstract draw() method

  public void draw() {

    System.out.println("Drawing a circle...");

  }


  // Provide an implementation for inherited abstract getArea() method

  public double getArea() {

    return Math.PI * radius * radius;

  }


  // Provide an implementation for inherited abstract getPerimeter() method

  public double getPerimeter() {

    return 2.0 * Math.PI * radius;

  }

}


class ShapeUtil {

  public static void drawShapes(Shape[] list) {

    for (int i = 0; i < list.length; i++) {

      list[i].draw(); // Late binding

    }

  }


  public static void printShapeDetails(Shape[] list) {

    for (int i = 0; i < list.length; i++) {

      String name = list[i].getName(); // Late Binding

      double area = list[i].getArea(); // Late binding

      double perimeter = list[i].getPerimeter(); // Late binding


      System.out.println("Name: " + name);

      System.out.println("Area: " + area);

      System.out