testcasting.java

来自「此源码为机械工业出版社出版的《Java语言程序设计》第三版所配套的书中所有源代码」· Java 代码 · 共 39 行

// TestCasting.java: Demonstrate casting objects
public class TestCasting
{
  // Main method
  public static void main(String[] args)
  {
    // Declare and initialize two geometric objects
    GeometricObject geoObject1 = new Circle(5);
    GeometricObject geoObject2 = new Cylinder(5, 3);

    // Display circle
    displayGeometricObject(geoObject1);

    // Display cylinder
    displayGeometricObject(geoObject2);
  }

  // A method for displaying a geometric object
  static void displayGeometricObject(GeometricObject object)
  {
    System.out.println();
    System.out.println(object.toString());

    if (object instanceof Cylinder)
    {
      System.out.println("The area is " +
        ((Cylinder)object).findArea());
      System.out.println("The volume is " +
        ((Cylinder)object).findVolume());
    }
    else if (object instanceof Circle)
    {
      System.out.println("The area is " + object.findArea());
      System.out.println("The perimeter is " +
        object.findPerimeter());
    }
  }
}