Geographic information system - Software Development Case Studies in Java - page 401

addPoint(int x, int y) ), the entity selection (method contains(int x, int y) ), the
entity representation in XML format (method toXML() ), and the entity
visualization (method paint() ).
package gis.model;
import java.awt.*;
import java.util.*;
public abstract class MapEntity {
// variable "closed" is used to set the entity's endpoint
protected boolean closed # false ;
public MapEntity(){}
public void close() { this .closed # true ; }
public abstract void paint(Graphics2D g, Color color);
// these methods should be implemented in every subclass
public abstract void addPoint( int x, int y);
public abstract boolean contains( int x, int y);
public abstract String toXML();
}
public class MapSite extends MapEntity {
private Point2D point # null ; // the site's 2D location
private static int DIST # 4; // the site's radius in pixel
public MapSite(){}
// sets the site's coordinates
public void addPoint( int x, int y) {
point # new Point2D.Double(x, y);
}
// returns true if point x,y is inside the site's circle
public boolean contains( double x, double y) {
double dist # point.distance(x, y);
if (dist < # DIST) return true ;
return false ;
}
// converts the site's data to XML format
public String toXML() {
StringBuffer stream # new StringBuffer();
stream.append("\n <ENTITY>");
stream.append("\n <POINT X # " ! '"' !
( int )Math.round(point.getX()) ! '"' ! " Y # " ! '"' !
( int )Math.round(point.getY()) ! '"' ! "/>");
stream.append("\n </ENTITY>");
return stream.toString();
}
public void paint(Graphics2D g, Color color) { . . . }
}
public class MapLink extends MapEntity {
private static int DIST # 4;// link's surrounding in pixel