testshapelist.java

Beginning Java 2, SDK 1.4 Edition Exercise Code samples for this book

// Chapter 6 Exercise 2

// Tests the operation of the ShapeList class:

public class TestShapeList {
  public static void main(String args[]) {
    ShapeList shapes = null;	         // Stores a shape list.
    Shape shape = null;                  // Stores a shape.
    int shapeCount = 10;                 // Number of shapes.
    Point[] pts;			 // Declare a variable referencing an array of points.
    Point pt1 = null;                    // First working Point store.
    Point pt2 = null;			 // Second working Point store.
    double minRadius = 2.0;		 // Minimum radius of a circle.
    double maxRadius = 20.0;		 // Maximum radius of a circle.
    double maxDist = 100.0;		 // Maximum x,y coordinate value.
    int minPts = 2;			 // Minimum number of points in PolyLines.
    int maxPts = 15;                     // Maximum number of points in PolyLines.
    int choice;                          // Selector for shape type.

    for(int i=0;i<shapeCount;i++) {					 
      // Generate one of four random shapes:
      choice = (int)(4.0*Math.random()); // Shape choice 0 to 3.

      // Coordinates are cast to int just to make the output less messy.
      // The compiler will arrange to cast the integer arguments back to double.

      switch(choice) {
	case 0:				 // Generate a Line:
          // Generate two random points:
	  pt1 = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));	
	  pt2 = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));
	  shape = new Line(pt1,pt2); 
	  break;

	case 1:				// Generate a Circle:
	  pt1 = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));	
	  shape = new Circle(pt1, (int)(minRadius+(maxRadius-minRadius)*Math.random()));
	  break;

	case 2:				// Generate a Rectangle:
          // Generate two random points
	  pt1 = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));	
	  pt2 = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));
	  shape = new Rectangle(pt1,pt2);	
	  break;

	case 3:				// Generate a PolyLine:
          // Create a Point array with a random number of elements:
	  pts = new Point[minPts+(int)((maxPts-minPts)*Math.random())];

          // Fill array with random points:
	  for(int j=0;j<pts.length;j++)
	    pts[j] = new Point((int)(Math.random()*maxDist),(int)(Math.random()*maxDist));

	  shape = new PolyLine(pts);	 // Create a PolyLine:
	  break;

        default:                         // We should never get to here.
          System.out.println("\nInvalid shape choice = "+choice);
          System.exit(1);
          break;
      }
      if(shapes == null)
        shapes = new ShapeList(shape);
      else
        shapes.add(shape);
    }

    // Output all the shapes in the Shape array:
    shapes.show();

  }
}