We wish to generate a class that embodies the characteristics of a two-dimensional point.
// Point.java // Definition of class Point (version 1) import java.awt.Graphics; /** * Point describes a two-dimensional point. */ public class Point { static final double SCALE = 100; private double x, y; // coordinates of the Point // No-argument constructor public Point() { setPoint( 0, 0 ); } // Constructor public Point( double a, double b ) { setPoint( a, b ); } // Set x and y coordinates of Point public void setPoint( double a, double b ) { x = a; y = b; } // get x coordinate public double getX() { return x; } // get y coordinate public double getY() { return y; } public void draw(Graphics g) { int nx = (int) (x*SCALE); int ny = (int) (y*SCALE); g.fillOval(nx-5,ny-5,11,11); } // convert the point into a String representation public String toString() { return " (" + x + ", " + y + ")"; } }
Class Point contains
draw
Object.toString()
// Test1.java import java.awt.*; import javax.swing.*; public class Test extends JApplet { Point pt[]; public void init() { pt = new Point[3]; pt[0] = new Point(0.1,0.1); pt[1] = new Point(0.5, 0.8); pt[2] = new Point(0.8,0.1); System.out.println("Points:" + pt[0] + pt[1] + pt[2]); } public void paint(Graphics g) { for (int i=0; i<pt.length; i++) pt[i].draw(g); } }
The test applet
Maintained by John
Loomis, last updated 6 June 2000