Example 23.15: The world class

package elharo.vrml;

import java.util.Vector;
import java.util.Enumeration;

public class world {

  String version = "#VRML V1.0 ascii\n\n";
  
  // a Vector to hold the different objects 
  // in the world
  Vector nodes;
  
  public world() {
    nodes = new Vector();
    nodes.addElement(version);
  }

  public void comment(String s) {
 
    nodes.addElement("#" + s);
      
  }
  
  public void addShape(shape s) {
    nodes.addElement(s.draw());
  }

  public void draw() {

    for (Enumeration e = nodes.elements(); 
      e.hasMoreElements();) {
      Object o = e.nextElement();
      // There are two possible classes in the 
      // Vector, shapes and Strings
      if (o instanceof shape) {
        shape sh = (shape) o;
        System.out.println(sh.draw());
      }
      else if (o instanceof String) {
        System.out.println((String) o);
      }
    }
    
  }

}