printandmeasureshapes.java

此程序可实现：在可视化界面中随即生成一些图形（长方形、椭圆、圆、正方形）；程序会自动告诉你所生成的图形的形状并计算这些图形的面积；最后程序会自动统计各个图形的分布。

import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
import java.util.ArrayList;

/**
 * A class to print and mesure the shapes. It will creat a windows and show
 * random number of rantangles and ovals with different colors.If the rectangle
 * is square rectangle,throw exception.Otherwise, show the area and perimeter of
 * rectangle. For oval,only show the area and perimeter when it is a circle.
 * 
 * @author Ruixiao Wu.
 * @version 1.0 26/06/2006.
 */

public class PrintAndMeasureShapes extends JApplet {

	/**
	 * A class extends JApplet.
	 * 
	 * @author Ruixiao Wu.
	 * @version 1.0 26/06/2006.
	 */
	private static final long serialVersionUID = 1L;

	public void init() {
		Container container = getContentPane();
		DrawPanel a = new DrawPanel();
		container.add(a);

	}

	class DrawPanel extends JPanel {
		/**
		 * A class extends JPanel.
		 * 
		 * @author Ruixiao Wu
		 * @version 1.0 26/06/2006.
		 */
		private static final long serialVersionUID = 1L;

		/**
		 * A method to paint the shapes.
		 */
		public void paintComponent(Graphics g) {
			super.paintComponents(g);
			Graphics2D g2 = (Graphics2D) g;
			g2.setPaint(Color.BLUE);
			g2.fillRect(0, 0, 300, 300);

			double leftX = 10;// the x coordinate.
			double topY = 10;// the y coordinate.
			Rectangle rect = new Rectangle();// creat a new object.
			Oval o = new Oval();// creat a new object.

			ArrayList<Rectangle2D> rectList = new ArrayList<Rectangle2D>();// creat
			// and
			// store
			// the
			// retangle
			// into
			// an
			// ArrayList.
			Rectangle2D j;// creat a new rectangle2D object.
			int numOfRec = rect.numOfRec();// initial the number of rectangle.

			for (int i = 0; i < numOfRec; ++i) {// a for loop to initial the
				// rectangle and draw them.
				rect.initList();
				rect.calculateArea();
				rect.calculatePerimeter();
				double rectWeigth = rect.RecList.get(0);
				double rectLength = rect.RecList.get(1);

				j = new Rectangle2D.Double(leftX, (topY + i * 35), rectWeigth,
						rectLength);
				rectList.add(j);

				g2.setPaint(Color.RED);//set color.

				try {// the exception.

					if (rect.checkParam() == true) {
						g2.fill(rectList.get(i));
						g2.drawString("The area is:" + rect.getArea()
								+ " square cm." + "   The Perimeter is:"
								+ rect.getPerimeter() + "cm", (int) (leftX),
								(int) (topY + 28 + i * 30));
					} else
						throw new IllegalRectangleException();

				} catch (IllegalRectangleException e) {
					g2.drawString(
							"This is not a valid rectangle! I do not print!",
							(int) (leftX), (int) (topY + 28 + i * 30));
					rectList.remove(i);
				}
			}

			ArrayList<Ellipse2D> ovalList1 = new ArrayList<Ellipse2D>();// creat and
			// store the
			// oval into
			// an
			// ArrayList.
			Ellipse2D k;// creat a new rectangle2D object.
			int numOfOval = o.numOfOval();// initial the number of rectangle.

			for (int i = 0; i < numOfOval; ++i) {// a for loop to initial the
				// rectangle and draw them.
				o.initList();
				o.calculateArea();
				o.calculatePerimeter();
				int ovalWeigth = o.OvalList.get(0);
				int ovalLength = o.OvalList.get(1);

				k = new Ellipse2D.Double();
				k
						.setFrame(leftX, (topY + 100 + i * 35), ovalWeigth,
								ovalLength);
				ovalList1.add(k);

				g2.setPaint(Color.green);//set color.

				g2.fill(ovalList1.get(i));

				if (o.getArea() == 0)
					g2.drawString("This is a Oval!", (int) leftX,
							(int) (topY + 130 + i * 30));
				else
					g2.drawString("The area is:" + Math.round(o.getArea())
							+ "square cm." + "   The Perimeter is:"
							+ Math.round(o.getPerimeter()) + "cm.",
							(int) leftX, (int) (topY + 125 + i * 32));

			}

			g2.setPaint(Color.yellow);// print the result.
			g2.drawString("I print " + rectList.size() + " Rectangle, and "
					+ ovalList1.size() + " Oval.", (int) leftX,
					(int) (topY + 250));

		}// End method paintComponent.
	}// End class DrawPanel.
}// End class PrintAndMeasureShapes.